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NeuroImage 48 (2009) 564–584
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NeuroImage
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Review
Understanding others' actions and goals by mirror and mentalizing systems:A meta-analysis
Frank Van Overwalle ⁎, Kris BaetensVrije Universiteit Brussel, Belgium
⁎ Corresponding author. Department of Psychology, VE-mail address: [email protected] (F. V
1053-8119/$ – see front matter © 2009 Elsevier Inc. Aldoi:10.1016/j.neuroimage.2009.06.009
a b s t r a c t
a r t i c l e i n f oArticle history:Received 13 February 2009Revised 28 April 2009Accepted 1 June 2009Available online 11 June 2009
This meta-analysis explores the role of the mirror and mentalizing systems in the understanding of otherpeople's action goals. Based on over 200 fMRI studies, this analysis demonstrates that the mirror system –
consisting of the anterior intraparietal sulcus and the premotor cortex – is engaged when one perceivesarticulated motions of body parts irrespective of their sensory (visual or auditory) or verbal format as well aswhen the perceiver executes them. This confirms the matching role of the mirror system in understandingbiological action. Observation of whole-body motions and gaze engage the posterior superior temporal sulcusand most likely reflects an orientation response in line with the action or attention of the observed actor. Incontrast, the mentalizing system – consisting of the temporo-parietal junction, the medial prefrontal cortexand the precuneus – is activated when behavior that enables inferences to be made about goals, beliefs ormoral issues is presented in abstract terms (e.g., verbal stories or geometric shapes) and there is noperceivable biological motion of body parts. A striking overlap of brain activity at the temporo-parietaljunction between social inferences and other, non-social observations (e.g., Posner's cuing task) suggests thatthis area computes the orientation or direction of the behavior in order to predict its likely end-state (orgoal). No conclusions are drawn about the specific functionality of the precuneus and the medial prefrontalcortex. Because the mirror and mentalizing systems are rarely concurrently active, it appears that neithersystem subserves the other. Rather, they are complementary. There seems, however, to be a transition fromthe mirror to the mentalizing system even when body-part motions are observed by perceivers who areconsciously deliberating about the goals of others and their behavioral executions, such as when perceivedbody motions are contextually inconsistent, implausible or pretended.
© 2009 Elsevier Inc. All rights reserved.
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565Two systems and their brain areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 566
Brain areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 566Identifying the mirror and mentalizing systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567Does the mirror system support the mentalizing system? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567Is there an alternative mechanism that infers goals for the mentalizing system? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568Results and discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569Perceptual and verbal information on moving body parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
Summary and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575Information on moving body parts and mentalizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
Summary and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577No information on moving body parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
Summary and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579
The mirror system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579The mentalizing system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580
rije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.an Overwalle).
l rights reserved.
565F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
Remaining questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580A transition from mirror to mentalizing system? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580Other social inferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581Further reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582
Introduction
Modern neuroscientific techniques and especially functionalmagnetic resonance imaging (fMRI) have greatly advanced ourunderstanding of how people make judgments about other people'sbehaviors, such as about their goals and intentions, desires, beliefs andtraits. Quickly understanding the actions and intentions of others iscrucial for maneuvering in our social world. The presentmeta-analysisexplores which brain areas are responsible for understanding theactions of others and the goals and motives underlying them. Actionsand goals can be ordered hierarchically according to their level ofabstractness or the time required to complete them. To give only oneexample (cf. Hamilton and Grafton, 2006; see Fig. 1), we candiscriminate motions (e.g., opening the hand), actions (often theconjunction of a motion sequence with an object, e.g., reaching orgrasping a cookie), immediate goals (e.g., take a cookie), and task goals(e.g., prepare a snack). In a social context, goals often imply longerperspectives and are often termed intentions (e.g., stay good friends,live a happy life). In this paper, we distinguish mainly between goalsthat reflect the immediate understanding of actions (i.e., immediategoals) versus task goals and other long-term intentions that reflect the“why” of an action. We differentiate less sharply between the lattercategories because their degree of abstractness and the time requiredfor their completion largely coincide.
We focus our analysis on the role of two hypothetical systems, themirror system and the mentalizing system. We explore their specificcontribution to the inference of intentionality and are also interestedin understanding how these two systems might interact. The functionof each of these systems is relatively well understood, althoughresearchers disagree on the specific details and processes.
• It is commonly assumed that the mirror system allows us torecognize the goal of a perceived action by matching it to a repre-sentation in our memory of our own actions. Thus, when observingan action represented in the observer's own behavioral repertoire,the goals associated with the observer's past actions are used tosimulate the goals of the other person (Gallese et al., 2004; Keysersand Gazzola, 2007; Keysers and Perrett, 2004; Uddin et al., 2007).
reach tolocation
take a cookie
p
Prospective Social intention
Task goal (Private intention)
Immediate goal
Action grit
Movements extend presthe arm the
Fig.1.Hierarchical organization of goals. A prospective social intention (anticipating a social iimmediate goals, each of which requires a sequence of basic actions, and each of which is ashown at each level, and the solid lines indicate components involved in preparing a romantfrom Fig. 1 of Hamilton and Grafton (2006), copyright 2006 by Society for Neuroscience, w
The mirror system allows one to sense rapidly and intuitively theother person's goals on the basis of low-level behavioral input, but islimited to familiar and frequently executed actions (Calvo-Merino etal., 2005; Calvo-Merino et al., 2006; Cross et al., 2006).
• The mentalizing system, also known as theory of mind (ToM),enables one to extract and understand the goals of others bydrawing on “social intelligence”, or the capacity to understand theother's thoughts and beliefs as though we could read the other'smind (Amodio and Frith, 2006). Although many species canaccurately predict the goals of their conspecific's behavior, itappears that only humans and perhaps some primates can separateone's own mental perspective from that of others (Emery, 2005).According to some authors, this sets the mentalizing system apartas a relatively high-level cognitive process (e.g., Amodio and Frith,2006; Gallagher and Frith, 2003). Although neuroscience researchindicates that this mentalizing system depends on brain areas thatare quite selectively involved in social thinking (i.e., about otherpeople; see Van Overwalle, 2009), little is known about the neuralprocesses and computations underlying it.
While some theorists argue that these two systems are largelymutually independent (e.g., Saxe, 2005; Jacob and Jeannerod, 2005), asubstantial numberof authors support the notion that themirror systemmight inform and support the mentalizing system (e.g., Agnew et al.,2007; Blakemore et al., 2004; Decetyand Chaminade, 2003; Keysers andGazzola, 2007; Ohnishi et al., 2004; Uddin et al., 2007; Van Overwalle,2009). Uddin et al. (2007, p. 156) noted that “although the exact natureof the interactions between these two networks is unknown, it is likelythat the direct connections between them facilitate integration ofinformation … across multiple domains”. Likewise, Etzel et al., (2008,p. e3690) have asserted that the “theory of mind processes … interactwith or even substitute for the output of the simulation circuits”, andOhnishi et al. (2004, p. 1486) have stated that the mirror system “isconsidered to be… a prerequisite for the higher-level of theory ofmind”.However, there is little evidence about precisely how these two systemsmay cooperate and inform each other.
Functional neuroimaging can provide answers in this theoreticaldebate because it can demonstrate whether and when these two
repare a dessert
prepare aromantic dinner
make appetizer
pour the milk pour the oil
asp transport liftem item item
hape close finger maintainhand for grip fingertip force
nteraction) may involve several (private) tasks goals, each of whichmay be composed ofssociated with an action that is composed of several movements. Some exemplars areic dinner (these components are highlighted with grey ovals). Adapted with permissionith examples from Ciaramidaro et al. (2007, p. 3106–7).
566 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
systems engage common or distinct functional networks in the brain.We see three possibilities. First, if the brain areas involved in mirrorand mentalizing tasks overlap, then the idea that both systems sharea common functional core would be strongly supported. Althoughthe assumption that location corresponds to function should be madewith some caution because each brain region may contain thousandsof neurons, each involved in different functions (Saxe et al., 2004;Henson, 2006), new methods such as classification of fMRI activa-tion patterns may distinguish more fine-grained levels of sepa-rate representations (e.g., Etzel et al., 2008; Dinstein et al., 2008).Second, if the brain areas subserving the mirror and mentalizingsystems do not overlap but are concurrently active during similartasks, then the two systems underlie different psychological pro-cesses as part of a single overarching functional network. Third, ifbrain areas subserving one system are activated during specific taskswhile the areas subserving the other system are inactive, then the twosystems might well be independent. In this last case, even thoughspecific tasks recruit each system in isolation, there might be somemore general tasks that could recruit both systems, and which mayprovide an insight into the conditions under which the two systemsinteract.
Recent fMRI research reveals that action understanding andmentalizing appear to recruit different brain areas. An extensivemeta-analysis by Van Overwalle (2009, p. 843) has shown that therepresentation of goals in the parietal cortex is located in differentanatomical areas when the understanding of visual actions wascompared with inferring goals from verbal stories. A distinctionbetween action understanding and mentalizing (i.e., inferring beliefs)has also been found within participants (Ohnishi et al., 2004; Gobbiniet al., 2007). Other manipulations also point to divergences betweenthe two systems when inconsistencies in actions are observed. Onestudy reported that the mirror system is more active when observerspassively perceive actions with an unusual goal (e.g., holding a cup atone's ear instead of one's mouth), whereas the mentalizing systembecomesmore activewhen they reflect consciously about this unusualintention (de Lange et al., 2008). Another study found that, evenwithout explicit reflection about goals, observing actions performed inan implausible way as opposed to a plausible way elicits greateractivity in brain areas responsible for mentalizing that lack mirrorproperties (Brass et al., 2007). These authors changed the plausibilityof an action by manipulating its context. For instance, turning on alight switch with the knee is a plausible thing to do when one's hands
Mirror System
-60
-40
-20
0
20
40
60
80
-120 -100 -80 -60 -40 -20 0 20 40 60 80-
Fig. 2. The regions of interest involved in the mirror and mentalizing system placed in an xTPJ (±50 −55 25), aIPS (±40 −40 45), PMC (±40 5 40) and mPFC (0 50 20). The PC (witand, in particular, on Keysers and Gazzola (2006, Fig. 1b) for the mirror system and on Va
are occupied by holding a large stack of books, but it is implausiblewhen both hands are free or holding only a small book.
Although these studies shed some light on the interaction betweenthemirror and thementalizing systems, they leave a number of crucialissues unanswered. What causes these distinctions? What engageseach system? Is it the type of action (hand versus shape motion;Ohnishi et al., 2004), the level of the goal (immediate versus task goalsversus intentions; Hamilton and Grafton, 2006), the format of theinput (visual versus verbal; Gobbini et al., 2007), or the level ofconscious reflection on intentionality (de Lange et al., 2008)?Obviously, some of these variables are confounded in current neuro-imaging research since visual action representations typically involveshort-time actions (e.g., grasping), immediate goals (e.g., grasp a cup),or task goals (e.g., prepare a snack), whereas verbally describedbehaviors often refer to task goals and long-term intentions (e.g.,prepare a wedding). In short, the precise conditions that cause aswitch from one system to another remain unclear. To understand theprocess of goal inference, we need to knowmore about the functionalspecificity of each system and the conditions inwhich each dominates.
We begin with a brief review of the functions and anatomy of themirror and the mentalizing systems. Given that there are probably asmany theoretical views on this matter as there are authors working inthis domain, this review is necessarily brief, selective, and confined tothose relevant to our major questions. Next, we present themethodology of the meta-analysis and discuss the results in view ofthe theoretical claims made earlier. Finally, we end with a shortconclusion and questions for further research.
Two systems and their brain areas
Brain areas
To study the potential overlap between brain processes andfunctions, we first must delineate the basic brain areas of the twosystems with some precision:
• Themirror system consists of the anterior intraparietal sulcus (aIPS)and the premotor cortex (PMC; see Fig. 2). Although some theoristsdefine the mirror system as consisting of different but highlyoverlapping regions, including the inferior parietal lobule and theinferior frontal gyrus (e.g., Rizzolatti et al., 2001), recent studies andreviews suggest that mirror activity can be more adequately limited
Mentalizing System
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80
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–y–z Talairach atlas. Their centers are indicated by a dot and are: pSTS (±50 −55 10),h center 0 −60 40) is not shown. The regions are drawn based on the recent literaturen Overwalle (2009, Fig. 1b) for the mentalizing system.
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to the “rostral part of theparietal lobule” (Gallese et al., 2004, p. 397),which consists mainly of the aIPS (see Tunik et al., 2007), whileactivity in the inferior frontal gyrus should be limited to its posteriorsector and extended to the “adjacent part of the premotor cortex”(Gallese et al., 2004, p. 397; see also Keysers and Gazzola, 2006),which effectively defines the PMC. The aIPS is located at the junctionof the anterior end of the intraparietal sulcus and the postcentralsulcus. This area is involved in the on-linemotor control of body-partmovements in relation to their goal objects (e.g., grasping a tool) andsubserves the execution as well as the observation of these goal-oriented movements (Tunik et al., 2007). The analysis of the PMC isfocused on Brodmann area (BA) 6which is anterior to the precentralgyrus, and a neighboring area known as the pars opercularis (BA 44)located at the inferior frontal gyrus of the PMC. The PMC identifiesthe goals or intentions of actions by their resemblance to storedrepresentations for these actions (e.g., through a direct matching or“resonance” of the corresponding motor circuits; Rizzolatti et al.,2001). The aIPS and PMC receive input from the superior temporalsulcus (STS), which contains polysensory neurons that respond tomotion from different perceptual modalities (Barraclough et al.,2005). These neurons parse the motion into a sequence of mean-ingful, coherent units that mark different spatial locations over timeor parse auditory input (including speech) intomeaningful temporalunits (Redcay, 2008). This meta-analysis focuses on the posteriorpart of the STS only, which is potentially involved in the identifica-tion of biologicalmotion and intentionality, unlike themore anteriorparts, which are involved in identifying motion per se (for a review,see Allison et al., 2000).
• The mentalizing system consists of the precuneus (PC), temporo-parietal junction (TPJ) and the medial prefrontal cortex (mPFC, seeFig. 2; Amodio and Frith, 2006;Mitchell, 2006; Saxe, 2006; Frith andFrith, 1999). The PC is located in the posterior medial brain, anteriorto theparieto-occipitalfissure, and is recruitedduringvisual imageryand retrieval of episodic information (see Cavanna and Trimble,2006) and changes in narrated structures and situations (Speer et al.,2007). The TPJ is located around the supramarginal gyrus, and themPFC in thismeta-analysis refers to the entiremedial areaof the PFC,including the anterior cingulate cortex. Although the TPJ seemsmostcrucial for the representation of goals and intentions in thementalizing system (see also Saxe and Powell, 2006), the mPFCplays a role in reflective reasoning about actions and judgments,including goals and intentions (e.g., de Lange et al., 2008; Van derCruyssen et al., 2009; see also Keysers and Gazzola, 2007). Based onhis meta-analysis, Van Overwalle (2009) proposed that the TPJ ismainly responsible for transient mental inferences about otherpeople such as their goals, desires and beliefs, while the mPFCsubserves the attribution ofmore enduring traits and qualities aboutthe self and other people.
Identifying the mirror and mentalizing systems
As noted above, it is assumed that mirror neurons enable the goalof biological motions to be detected by matching observed behaviorwith one's own behavioral repertoire and the most common goalsassociated with it. Neuroscientific research on mirror neurons withhumans typically focuses on tasks involving the observation andexecution of body motions and actions. For instance, in an observa-tion-only task, the participants observe a moving finger. In anobservation–execution task, the participants lift a finger in responseto themovement of the observed finger (imitation; e.g., Iacoboni et al.,1999). The mirror areas are then defined as those areas of the brainthat are recruited by both observation and observation–executiontasks of such dynamic body motions and actions as opposed to staticpositions (e.g., a static finger). Single-cell recording studies withmonkeys confirm that visual input in the STS is propagated to the aIPSfrom which it is passed to the PMC (Keysers and Perrett, 2004). The
PMC region is responsible for action planning and contains neuronsthat are sensitive to the goal of an action (e.g., grasping to eat or toplace in a container; Fogassi et al., 2005).
Research on mentalizing with humans has taken a different routeby focusing mainly on tasks that involve the representation of themental states of others, such as “false belief” tasks which test whetherchildren and adults can hold in their mind a belief about anotherperson that is different from their own (Saxe et al., 2004a). Forexample, participants are told a story about Sally, who puts her candyin a box and leaves the room. In her absence, another character movesthe candy to a basket. When Sally returns, the participant is asked toreport the content of the actor's belief (“Where will Sally look for hercandy?”). The right answer, that she will look in the box, requiresattributing a false belief to Sally that is distinct from one's ownknowledge. Most children before the age of 4 are unable to do this(Wimmer and Perner, 1983). However, there are no single-cell studiesthat could reveal how mentalizing processes are implemented at thelevel of neurons.
Does the mirror system support the mentalizing system?
The mirror system goes a long way towards explaining action fromdirectly observable sensory input in terms of immediate and task goals(e.g., Iacoboni et al., 2005). However, there is no evidence for theinvolvement of a mirror system in the inference of more abstract andcomplex forms of intentionality and mentalizing. One of the possiblemechanisms by which the mirror system could interact with thementalizing system would be that mirror neurons provide rapid andintuitive input to the mentalizing system. The identified goals from anobserved action could be the first step in the process of inferring moregeneral intentions (and other complex inferences such as disposi-tional traits and attributes of self and others) or in the process ofreflecting more consciously on these goal inferences. Van Overwalle(2009) has suggested the TPJ as the most likely candidate for such amentalizing area that interacts with the mirror system because of itsselective involvement in goal inferences and its close proximity to theaIPS.
However, many tasks that reveal the working of the mentalizingsystem are similar to false beliefs tasks and involve stories andcartoons of a higher complexity and abstractness than the meremovement of body parts such as grasping or touching. Consequently,not all the strategies employed to identify mirror properties inhumans (as detailed above) can be easily used to identify mentalizingproperties. Behaviors involving higher-level goals (e.g., preparing awedding) can easily be described verbally but are more difficult topresent visually in their totality, and often only some of theirsubcomponents can be so presented (e.g., paying for drinks at thecash register). This methodological limitation makes it potentiallymore difficult to find empirical evidence for the role of the mirrorsystem in high-level task goals. Parenthetically, this may also point totheoretical limitations in the role of the mirror system for under-standing more complex and abstract behavior and intentions.
Is there an alternative mechanism that infers goals for the mentalizingsystem?
A potential alternative is that the mentalizing system developedgoal-inferring properties of its own rather than relying on existingmirror areas. Several fMRI investigations support the hypothesis thatthe mentalizing function has evolved from a set of lower-levelprocesses that share some elementary function with it (e.g., Decetyand Lamm, 2007). This elementary mentalizing function might be abasic distinction between actions generated by the self versus others(Brass et al., 2005). Related to this self-other distinction is anothernecessary function that focuses one's attention on external targetsthat are relevant because some of them are social targets with their
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own goals and beliefs. A recent meta-analysis by Decety and Lamm(2007) documented that orienting one's attention in a novel direction(using Posner's cueing task) recruits the same TPJ area as mentalizing(using false belief stories), and this was confirmed even within thesame participants (Mitchell, 2008). In Posner's task, participants aregiven a cue (e.g., an arrow pointing to the right or left) after which atarget appears at the cued location (valid trials) or at another location(invalid trials). During invalid trials, the observer has to orient his orher initial attention to a novel place in space, and this processdemands more mental activity and time than do valid trails.
In analogy with the spatial “where” functionality of the dorsalstream of the visual network, Van Overwalle (2009) interpreted thisoverlap as an indication of the TPJ's “where-to” functionality, that is,it orients to externally generated behaviors with the aim ofidentifying the possible end-state of these behaviors. This end-statereflects the goal of a behavior (and probably also the beliefs of theactor on how the goal can be attained). For instance, if a person asksdirections to a train station, walks in the direction of the train station,and enters the building, perceivers can be pretty sure that thisperson's goal is to take a train as all these actions point to that end.According to Redcay (2008), the sensitivity of parietal areas toorientation may have been supported by the development of jointattention (e.g., gaze and pointing) between an infant and a caretaker.A child learns that orienting in the same direction as a gaze orgestures of a caretaker often results in finding new or interestingobjects, which is important not only for learning words and conceptsin the world but also for learning about other people's interests andgoals.
Several lines of research provide indirect evidence for thesuggestion that the TPJ is involved in the orientation towards relevantbehavioral goals. The lateral parietal area (including the TPJ) isinvolved in guiding spatial attention to rewarding or task-relevantobjects and movements (for reviews, see Corbetta and Shulman,2002; Gottlieb, 2007; Husain and Nachev, 2006). This area in humansalso responds to changes in the direction of motion (Donner et al.,2007; Martinez-Trujillo et al., 2007; Shulman et al., 2001). Moreover, asingle-cell study on rhesus monkeys documented that this sensitivityto direction can be modulated by more abstract stimulus properties,such as arbitrary direction categories, and that firing shifts after themonkeys are retrained to group the same stimuli into new categories(Freedman and Assad, 2006).
In sum, some researchers claim that the mentalizing functionbuilds on the output of the mirror system (e.g., Etzel et al., 2008),while other authors suggest that this might depend on an evolutio-narily older function that is also involved in orientation (e.g., Decetyand Lamm, 2007; Van Overwalle, 2009). The present meta-analysispresents data that may shed some light on this controversy.
Method
The studies reviewed in this article were taken from an earliermeta-analysis on social cognition by Van Overwalle (2009) andupdated by including recent studies located by searches in PubMedand ScienceDirect identified by the term “fMRI” alongwith at least oneof the following terms in the title or abstract: “person”, “social”,“mirror” or “mind”. The search for this update was confined to theperiod between April 2007 and August 2008, and resulted in anincrease of more than one third for the mentalizing studies. Toaugment these studies with research into other functions that mightbe relevant to social cognition and as such might activate the samebrain areas, additional fMRI studies that also appeared betweenJanuary 2000 and April 2007 were included when referenced in theprevious articles and for the following tasks:
• Grasp execution studies listed in the meta-analysis by Tunik et al.(2007).
• Human motion perception studies listed in the review by Pelphreyet al. (2005).
• Mirror neuron studies listed in the meta-analysis by Morin andGrèzes (2008) and Turella et al. (2009).
• Mentalizing and moral studies as well as body (part) animationsand motions reviewed by Gobbini et al. (2007).
• Mentalizing and attention (reorienting) studies from the meta-analysis by Decety and Lamm (2007).
Studies were included only if they investigated unmedicatedhealthy children or adults, used fMRI scanning (unless reportedotherwise), involved non-emotional stimuli or tasks, and reported thecoordinates of activations in the space of the MNI template (Collinset al., 1994) or the atlas of Talairach and Tournoux (1988). Whenactivations were reported in MNI space, they were transformed intoTalairach and Tournoux coordinates by means of a non-linear trans-formation (http://imaging.mrc-cbu.cam.ac.uk/imaging/MniTalairach)so that all the coordinates were in a common stereotaxic framework.We restricted our focus to the regions of interest in both hemispheres(when relevant; see also Fig. 2): the precuneus (PC), posterior part ofthe superior temporal sulcus (pSTS), temporo-parietal junction (TPJ),anterior intraparietal sulcus (aIPS), lateral premotor cortex (PMC),and medial prefrontal cortex (mPFC; including the anterior part ofthe cingulate cortex). The hypothesized peaks of these regions aredenoted by a dot in Fig. 2 and their coordinates (rounded to thenearest 5mm) are list in the figure note. These regions of interest weredefined minimally as a sphere of 20 mm radius around thesehypothetical peak coordinates or maximally as the larger regionsdepicted anatomically in Fig. 2. The anatomical borders were based onthe literature, including specifically Keysers and Gazzola (2006, Fig.1b) for the mirror system and Van Overwalle (2009, Fig. 1b) for thementalizing system. In addition, each activation peak was classified asmedial when its distance on the x-axis (left–right axis) did not exceed20 mm (see the anatomical definition of the medial frontal gyrus atwww.talairach.org; see also Van Overwalle, 2009), although moststudies were within a 12 mm distance (see Table 1).
Given the lack of clear anatomical definitions for the pSTS and theTPJ, these regions were defined by their minimal sphere of 20 mmradius. Although the reported loci of the pSTS and the TPJ are stronglyoverlapping in a 5 to 30 mm z-coordinate zone, we decided tosegregate them because the brain areas involved in the mirror tasks ofthis meta-analysis tend to be more inferior than in the mentalizingtasks (this has also been found within participants, see Gobbini et al.,2007). In linewith this general observation, the greatmajority of peaks(averaged across both hemispheres) with z-coordinates b15mmwereclassified as pSTS and peaks with z-coordinates ≥15 mm as TPJ.Furthermore, a small minority of peaks in mirror tasks between 15 to30 mm were categorized as pSTS (i.e., 16 peaks or 6% for Tasks 1–6;with the highest percentage of 21% in Task 6) and peaks inmentalizingtasks between 0 to 15mmwere categorized as TPJ (i.e., 22 peaks or 12%for Tasks 7–12;with the highest percentage of 25% inTask 7). Note thatthe substantial overlap between the pSTS and TPJ for these latter peakscautions againstmaking any strongdistinction between them. Becausethere is no clear consensus on the anatomical definitions of all theregions of interest, for exploratory reasons, wewere somewhat lenientand included some coordinates just outside these regions. These areclearly indicated in bold and red in Table 1.
In order to create sufficiently large samples of comparablefunctions of mental processes, we identified task categories withtask components that were most similar among a set of studies.Within each task category, the stimulus material was rankedaccording to its input format (visual, auditory, tactile to verbal),the body parts involved (finger, hand, face, limb to feet), andwhether the motion involved an object or not. When the descriptionof tasks, stimuli and especially instructions was not clear-cut (e.g., noexample or verbatim reports), the characterization by the authors
569F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
was used for categorization. Classification of all the studiesproceeded in two steps. The initial classification of conditions andcoordinates was made after a first reading of each article by the firstauthor. The second classification was made by the second author andin case of disagreement, a final decision was made after discussion.This second reading generally confirmed the initial subdivision oftask categories and coordinates (with an agreement of N90%),although a few were changed. Table 1 lists all the studies includedin this meta-analysis. We included all the studies with tasks thatbelonged to a category, even if their peak activation coordinates didnot fall within any of the expected regions, so that the proportion ofstudies satisfying the expected localization could be estimated. Thereported coordinates were restricted to significant contrasts invol-ving a comparison between an experimental versus a base-linecontrol task.
Activations were accepted as significant according to the criteriaset by each study. To ensure that the activation peaks entered into themeta-analysis resulted from independent contrasts, the reportedcoordinates were restricted to one per study, task category andcondition of interest. In a few cases, multiple activations werereported, one for each different task component (e.g., two differentcontrol conditions or instructions) or for each distinct sample ofparticipants. The retained coordinates concerned the most significantactivation peak in each of the regions of interest.
Because statistical tests were computed on dichotomous data(i.e., the presence or absence of activation), all the tests were non-parametrical. Given that the comparisons involved more than 2groups of conditions, we used Cochran's Q for testing betweendifferent brain areas within the same individual studies, andKruskal–Wallis analysis of variance (ANOVA) for testing betweendifferent sets of studies (e.g., task categories) in the same brainarea. Cochran's Q is an extension of a χ2 test. Kruskal–Wallis'ANOVA is an extension of the Mann–Whitney U rank test, and itsinterpretation is basically identical to that of the parametric one-way ANOVA. Differences in percentages at different hemisphereswere computed with parametric tests. All these tests wereimplemented in Statistica 8.0.
Results and discussion
All the coordinates involved in this meta-analysis are listed in Table1. Because of space limitations, we list only the regions of interest for agiven system. The main results and statistical tests for all of theregions of interest for each system are summarized in Table 2. Asshown in Table 2, Cochran tests reveal that all the tasks eliciteddifferential activation in these regions, which is consistent with theidea that different areas are preferentially engaged in distinct pro-cesses (i.e., tasks) of inferring intent. In addition, Kruskal–Wallis'ANOVAs show the extent to which activations are consistent or diffe-rent for several similar task categories (they are discussed in sub-sequent sections).
A sharp distinction can be drawn between (a) the presence or theabsence of information on articulated movements of body parts and(b) on the activity in the mirror versus the mentalizing areas asdefined earlier. Hence, Table 1 is divided into three sections infunction of these two criteria: tasks that involve human motorperformance and observation of moving body parts and the activationof the mirror system (Tasks 1–6), tasks that involve the same inputand deliberative thinking about an action that activates thementalizing system (Task 7), and tasks that involve inferences ofintentionality without observed body motions and recruit thementalizing system (Tasks 8–12). We report the results for all of thesections separately. Given the great amount of findings (see Table 1),the results are reported and briefly interpreted for each task categoryseparately. Finally, we summarize and discuss these results at somelength after each section.
Perceptual and verbal information on moving body parts
The first section of Table 1 lists a large set of fMRI studies on theexecution and observation of human motion. Within each taskcategory, the studies are first ranked according to input format(visual, auditory or verbal) and then according to the body-partinvolved (from finger to toe). Figs. 3A, B depict the coordinates fromthe table for motor execution tasks (Task 1), human motionobservation tasks (Tasks 2–4), while motor imitation combines both(Task 5). Note the large agreement with the putative networkssubserving the human mirror system as depicted by Keysers andGazzola (2007). Although execution of human motions (Task 1) is notpart of this meta-analysis per se, in order to provide some backgroundon the mirror system, studies on self-generated hand motions (e.g.,grasping) are presented first in Table 1. Grasp motions are the moststudied human motion in mirror research because of the obviouslimitations on motion within an fMRI scanner.
Given that most studies on understanding action and mirrorneurons involve finger and hand manipulations (Task 2 and 5), weshould expect a substantial overlap with the brain areas that supportself-generated hand execution (Task 1). To probe how the mirrorsystem is involved in goal representation, we also review tasks wherethe usual goal of human motion is manipulated (Task 6; see also Figs.3C, D). The meta-analysis shows the predicted strong activation in themirror areas: the anterior part of the intraparietal sulcus (aIPS) as wellas the premotor cortex (PMC). In contrast, motions of whole bodies aswell as gaze (Task 3 and 4) involve mainly the posterior superiortemporal sulcus (pSTS).
These initial observations are confirmed by Kruskal–Wallis'ANOVA (see Table 2). While most areas show significant differencesin activation across Tasks 1 to 6, after the deviant Tasks 3 and 4 areexcluded, all right lateralized regions of interest show a remarkablysimilar (i.e., non-significant) patternwith the highest activation in themirror areas aIPS and PMC, while the pSTS (that provides input to themirror system) is activated to a lesser degree.
1. Execution of hand motion: The execution of hand motionsinvolves the anterior part of the intraparietal sulcus (aIPS) as well asthe premotor cortex (PMC). The activation of the aIPS, which controlsthe motion of the hand in relation to the spatial and functionalposition of the object (Tunik et al., 2007), is more often identified inthe left hemisphere (96%) than in the right (71%, pb .05). The PMC isactivated in only half of the cases (54% bilaterally). However, if studieswith less adequate control conditions that still involve the same typeof object manipulation (i.e., planning or imagining a grasp and verysimilar hand motions such as squeezing and pointing; see Table 1yellow background) are not considered, the involvement of the PMCincreases to 79%. Given the large overlap with action understandingstudies discussed next (Tasks 2, 5 and 6), many coordinates of Task 1are obscured in Figs. 3A, B by the coordinates of these latter studies.
2. Body-part motion: Of crucial importance is that understandingthemotions of body parts – including the handwaswell as the fingers,face (including the mouth) and legs (including the feet) – recruits thesame areas as self-generated motion: the aIPS and the PMC. Theactivation occurs irrespective of the visual, auditory or even verbalmodality of the input (for the latter formats, see the last rows of Task2). Thus, listening to stepping feet or tearing a paper as well as readingthe words “kicking” or “biting” recruits the mirror system. This is inline with the finding that auditory and visual signals are integrated inthe STS (for reviews see Barraclough et al., 2005; Pulvermüller, 2005).The activity of body-part motions recruits both hemispheres, not onlyin the aIPS (51% vs. 49%, ns) but also in the PMC (76% vs. 60%, p=.11).The activation in the aIPS seems less consistent than the activation inthe PMC. However, removing less adequate studies that lack goal-directed manipulation of objects (object-related) or no-movementcontrol conditions (see yellow background in Table 1) raises thesenumbers to 75% and 63% for the left and the right aIPS respectively.
Table1
Major
task
catego
ries,stimuli,instructions
,con
dition
san
dco
rrespo
ndingTa
lairachco
ordina
tes.
MO
VIN
G B
OD
Y PA
RTS
& M
IRRO
R A
REA
S
Stud
yYe
arSt
imul
iIn
stru
ctio
nTa
rget
Cont
rol
MIR
ROR
ARE
AS
1. E
xecu
tion
of h
and
mot
ion
New
man
-Nor
dlun
d et
al.
Frid
man
et a
l. K
rolic
zak
et a
l. Cu
lham
et a
l. Bu
ccin
o et
al.
Mak
uuch
i Sh
ikat
a et
al.
Ehrs
son
et a
l. Eh
rsso
n et
al.
Choi
et a
l. Ch
oi e
t al.
Bink
ofsk
i et a
l. Bi
nkof
ski e
t al.
Bink
ofsk
i et a
l. Sc
hnel
l et a
l. Jo
hnso
n-Fr
ey e
t al.
John
son-
Frey
et a
l. Fr
ey e
t al.
Bink
ofsk
i et a
l. Sh
ikat
a et
al.
Janc
ke e
t al.
Janc
ke e
t al.
Janc
ke e
t al.
Janc
ke e
t al.
r-pS
TSl-
aIPS
r-aI
PSl-
PMC
r-PM
C
2008
20
06
2007
20
03
2004
b
2005
20
03
2001
20
01
2001
20
01
1999
b#
1 19
99 b
#2
1999
a
2007
20
05
2005
20
05
1998
20
03
2001
20
01
2001
20
01
hand
mot
ion
hand
mot
ion
hand
mot
ion
hand
mot
ion
hand
mot
ion
hand
mot
ion
(no
obje
ct)
hand
mot
ion
hand
mot
ion
hand
mot
ion
hand
mot
ion
(lef
t han
d)
hand
mot
ion
(rig
ht h
and)
ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n
lifti
ng a
vir
tual
bar
m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g im
agin
ing
mot
ion
mov
ing
mov
ing
mov
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mov
ing
mov
ing
mov
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+ na
min
g ob
ject
m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g m
ovin
g
join
t gra
spin
g gr
aspi
ng o
bjec
t gr
aspi
ng
gras
ping
gr
aspi
ng
dela
yed
mot
ion
im
agin
ing
gras
p gr
ip fo
rce
smal
l gri
p fo
rce
pant
omim
ing
gras
p pa
ntom
imin
g gr
asp
expl
orin
g co
mpl
ex o
bjec
ts
expl
orin
g co
mpl
ex o
bjec
ts
expl
orin
g co
mpl
ex o
bjec
ts
mot
ion
by s
elf
gras
ping
(rig
ht h
and)
gr
aspi
ng (l
eft h
and)
gr
aspi
ng
gras
ping
pa
ntom
imin
g gr
asp
expl
orin
g ob
ject
s m
odel
ing
obje
cts
expl
orin
g ob
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s m
odel
ing
obje
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solo
gra
spin
g m
otio
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itho
ut o
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achi
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reac
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no
mot
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imm
edia
te m
otio
n or
ient
atio
n di
scri
min
atio
n no
gri
p fo
rce
larg
e gr
ip fo
rce
finge
r m
otio
n fin
ger
mot
ion
expl
orin
g si
mpl
e ob
ject
s ex
plor
ing
sim
ple
obje
cts
expl
orin
g si
mpl
e ob
ject
s m
otio
n by
com
pute
r pl
anni
ng th
e gr
asp
only
pl
anni
ng th
e gr
asp
only
po
inti
ng
poin
ting
im
agin
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gras
p
sque
ezin
g sq
ueez
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imag
inin
g im
agin
ing
−45
−
51
−51
−58
−
62
−61
8
1
−9
0.13
−36
−
40
−47
−
38
−57
−
39
−39
−
40
−36
−
36
−40
−
40
−48
−
50
−36
−
40
−40
−
45
−30
−
44
−40
−
44
−48
−56
−
48
−34
−
48
−18
−
54
−39
−
40
−48
−
48
−40
−
40
−34
−
53
−29
−
31
−33
−
35
−45
−
37
−41
−
29
−29
38
36
37
52
18 36
51
36
56
56
40
40
40
47
40
33
43
43
45
39
39
38
38
0.9
6
36
43
40
51
36
45
48
52
40
40
48
45
36
32
40
40
−58
−37
−
50
−29
−
45
−39
−
52
−44
−40
−
40
−34
−30
−
41
−37
−
29
−37
47
42
50
42
36
39
52
48
44
44
40
39
43
39
38
39
0.7
1
−48
−
52
−30
−
59
−42
−64
−24
−
16
−52
−
60
−52
−36
17 8
−11
9 6 0 0 −
12 8 12 8
−5
23
8
61
23
24
16
56
64
28
8
22
0.7
9
48
0.5
4
48
54
29
53
54
51
40
48
52
52
56
40
20 9
−10
8 9 9 0 4 8 8 8
−5
21
34
63
11
15
27
32
28
20
16
20
0.7
9
48
0.5
4
63
59
64
−39
−54
−
52
6 0 5 0.13
2. B
ody
part
mot
ion
Baum
gaer
tner
et a
l.G
azzo
la e
t al.
Ham
zei e
t al.
Vill
area
l et a
l.Pi
erno
et a
l.M
olna
r-Sz
akac
s et
al.
Gro
sbra
s an
d Pa
usO
hnis
hi e
t al.
Bucc
ino
et a
l.M
anth
ey e
t al.
Bucc
ino
et a
l.En
gel e
t al.
Val
year
et a
l.Ch
ao a
nd M
arti
nCh
ao a
nd M
arti
n Bu
ccin
o et
al.
Bucc
ino
et a
l. Bu
ccin
o et
al.
Sant
i et a
l.Ca
lver
t and
Cam
pbel
lBu
ccin
o et
al.
Gro
sbra
s an
d Pa
usW
heat
on e
t al.
2007
2007
a 20
0320
0820
06a
2006
2006
2004
#1
2004
b20
0320
0120
0820
0720
00#
120
00#
220
04b
2004
a20
04a
2003
2003
2001
2006
2004
hand
mot
ion
hand
mot
ion
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mot
ion
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mot
ion
hand
mot
ion
hand
mot
ion
hand
mot
ion
hand
mot
ion
hand
mot
ion
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mot
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hand
/ ar
m m
otio
npi
ctur
es o
f gra
spab
le o
bjec
tspi
ctur
es o
f han
d to
ols
pict
ures
of h
and
tool
spi
ctur
es o
f han
d to
ols
pict
ures
of h
and
tool
sm
outh
mot
ion
mou
th m
otio
nm
outh
poi
nt li
ghts
mou
th m
otio
n (s
peec
h)m
outh
mot
ion
face
mot
ion
leg
mot
ion
view
ing
view
ing
view
ing
view
ing
view
ing
view
ing
view
ing
view
ing
view
ing
view
ing
+ co
rrec
t?vi
ewin
gvi
ewin
g +
gras
pabl
e?vi
ewin
g +
nam
ing
view
ing
view
ing
+ na
min
gvi
ewin
gvi
ewin
gvi
ewin
gvi
ewin
gvi
ewin
gvi
ewin
gvi
ewin
gvi
ewin
g
gras
ping
obj
ect
gras
ping
obj
ect
gras
ping
obj
ect
gras
ping
obj
ect
gras
ping
obj
ect
gras
ping
obj
ect
gras
ping
obj
ect
gras
ping
obj
ect
gras
ping
obj
ect
mot
ion
wit
h ob
ject
gras
ping
obj
ect
gras
ping
obj
ect
tool
sto
ols
tool
sto
ol-t
o-gr
asp
mot
ion
(bit
ing
obje
ct)
mot
ion
(sile
nt s
peec
h)m
otio
nm
otio
nm
otio
nm
otio
nm
otio
n (w
alki
ng o
n flo
or)
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
no m
otio
nto
ol m
otio
nno
mot
ion
no m
otio
not
her
gras
pabl
e ca
tego
ries
othe
r cat
egor
ies
othe
r cat
egor
ies
no m
otio
nno
mot
ion
no m
otio
nra
ndom
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
−56−
30−
56−
40
−48−
51−
42
−36−
59
−36−
32−
30−
50−
32
−32−
36
−26
−22−
46−
39−
42
−40−
25−
40
−40−
28−
47−
47−
39−
31−
45
−52−
52
−52
34 56 41 48 52 38 54 52
32 45 42 47 46 43 40 56
38
−
50−
22
−26−
48−
36−
58−
49
−56−
59−
48−
42−
50−
48−
59−
55−
51−
44−
56−
44−
55
7 −1
−3 9 −5 11 0 −4 10 2 6 3 4 5 24 9 −4 0 −1 5
25 48 48 25 54 27 32 44 24 35 23 25 31 29 17 30 42 36 52 26
40 34
26 34 51 40 40
40 59 44 36 34 52
40
−38
−60−
38−
44−
48−
45
−35−
40−
27
−35−
48
−48−
32
−42
55 54 55 52 54 55 41 52 48 44 50 40 44 44
42 34 42 55 52 57 46 48 55 40 46 46 48 48 28
13
4
−6
11
20
3
−2 0
7
13
8
2
0
6
0
32 46 32 29 24
29 32 44 33 22 23
44 32 44 39
−54−
53
−51
−44
−55
−48
−48
−44−
42
−62
−63
−35
−46
−46
12
13
3
2
−5
4
6
52 44
64 50 54 51
−68
−54−
40
−43
−50
−54
−4 10 9 4 4 10
l-pS
TS
570 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
Bucc
ino
et a
l.Pe
lphr
ey e
t al.
Pelp
hrey
et a
l.Sa
krei
da e
t al.
Ram
nani
and
Mia
llD
avid
et a
l.D
avid
et a
l.Jo
hnso
n-Fr
ey e
t al.
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le a
nd C
hatt
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stan
tini
et a
l. Bu
ccin
o et
al.
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aton
et a
l.Bu
ccin
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al.
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et a
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al.
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eau
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l.D
ubea
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al.
Gal
ati e
t al.
Bide
t -Ca
ulet
et a
l.Ba
umga
ertn
er e
t al.
Tett
aman
ti e
t al.
Nop
pene
y et
al.
20
0120
0520
0520
0520
0420
0820
0620
0320
0620
0520
0120
0420
0120
0420
0120
0120
0120
0820
0520
0720
0520
05
view
ing
view
ing
view
ing
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ing
self
or o
ther
mot
ion
view
ing
+ pr
efer
ence
?vi
ewin
g +
agen
t?vi
ewin
gvi
ewin
gvi
ewin
gvi
ewin
gvi
ewin
g vi
ewin
gvi
ewin
gvi
ewin
g vi
ewin
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glis
teni
nglis
teni
ngsi
lent
read
ing
liste
ning
to r
ead
sent
ence
sse
man
tic
judg
men
t
mot
ion
(wit
h ob
ject
)m
otio
nm
otio
nfin
gers
or
mou
th m
otio
n m
otio
n by
oth
erpr
efer
ence
by
othe
rot
her
gras
ping
obj
ect
new
mot
ion
hum
an m
otio
nha
nd m
otio
nm
otio
nm
otio
nm
otio
nm
otio
nm
otio
nm
otio
nm
otio
n (a
udit
ory)
mot
ion
(wal
king
on
floor
)gr
aspi
ng o
bjec
tm
otio
nm
otio
n
24 28 57 51 34 49 42
49 52 52 55 46 55 48 50 60 58 57
-66
-36
-37
-51
-46
-54
-60
-43
-48
-42
-45
0 5 6 27 11 6 2 4 16 6 16
-59
-53
-48
-55
-52
-62
-57
-42
-55
-52
-47
-50
-38
-63
9 12 14 2 14 0 6
0.3
1 0
.38
0
.51
0
.49
0.76
0.60
foot
mot
iona
nim
ated
han
d m
otio
nan
imat
ed m
outh
mot
ion
finge
rs /
mou
th m
otio
nfin
ger
mot
ion
hand
mot
ion
hand
mot
ion
(bal
l tos
s)ar
m m
otio
nlim
b m
otio
n (±
obj
ects
)ha
nd m
otio
n (n
o ob
ject
)ha
nd /
arm
mot
ion
(no
obje
ct)
hand
mot
ion
(no
obje
ct)
mou
th m
otio
n (n
o ob
ject
)fa
ce m
otio
n (n
o sp
eech
) fo
ot m
otio
n (n
o ob
ject
)ha
nd m
otio
n (n
o ob
ject
)m
outh
mot
ion
(no
obje
ct)
hand
/mou
th m
otio
n (n
o ob
ject
)le
g m
otio
nha
nd a
ctio
n se
nten
ces
mou
th /
hand
/ le
g se
nten
ces
hand
/ bo
dy a
ctio
n ve
rbs
no m
otio
nno
mot
ion
no m
otio
nm
otio
n of
hum
an jo
ints
mot
ion
by c
ompu
ter
pref
eren
ce b
y se
lfse
lfto
uchi
ng o
bjec
tol
d m
otio
nob
ject
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
no m
otio
nno
mot
ion
-32
-40
-37
-39
-57
-64
-29
-41
-56
-36
60
0
.75
38
44
44
30
-60
-52
-34
-33
-35
-47
-30
6
8
0.6
3
41
5
1
3
9
4
0
3
6
32
-32
-46
-51
-53
-45
-51
-60
-52
-40
-55
-47
-56
-52
-8
5
23
0
18
9
-4
4
-4
10
-4
13
10
64 0.8
8 21 30 22 2 18 40 44 60 11 18 21 16
40 46 42 44 54 52 42 52 46 44 54
-4 11 4 6 4 0 6 0 15 -4 20
60 0.6
7 23 43 46 32 48 44 32 36 56 26
Cart
er &
Pel
phre
yBe
auch
amp
et a
l.Be
auch
amp
et a
l.Be
auch
amp
et a
l.G
obbi
ni e
t al.
Peel
en e
t al.
Peus
kens
et a
l.Sa
ygin
et a
l.Sa
nti e
t al.
Serv
os e
t al.
Gro
ssm
an &
Bla
keV
aina
et a
l.G
rèze
s et
al.
Saxe
et a
l. M
orri
s et
al.
4. G
aze
Pier
no e
t al
. Pi
erno
et
al.
Mat
erna
et
al.
Will
iam
s et
al.
Mos
coni
et
al.
Sato
et
al.
Bris
tow
, Ree
s &
Fri
th
Schi
lbac
h et
al.
Pelp
hrey
et
al.
Pelp
hrey
et
al.
Dub
eau
et a
l. H
ooke
r et
al.
Hof
fman
& H
axby
Puce
et
al.
2006
2003
2002
2002
#1
2007
#2
2006
2005
#1
2004
2003
2002
2002
2001
2001
2004
#1
2005
#1
3. W
hole
bod
y m
otio
n
who
le-b
ody
mot
ion
who
le-b
ody
mot
ion
who
le-b
ody
mot
ion
who
le-b
ody
mot
ion
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
poin
t lig
hts
who
le-b
ody
mot
ion
self
mov
ing
(vir
tual
rea
lity)
view
ing
disc
rim
inat
ion
mat
chin
gm
atch
ing
view
ing
view
ing
view
ing
view
ing
view
ing
view
ing
view
ing
disc
rim
inat
ion
view
ing
view
ing
view
ing
biol
ogic
al m
otio
nbi
olog
ical
mot
ion
biol
ogic
al m
otio
nbi
olog
ical
mot
ion
biol
ogic
al m
otio
nbi
olog
ical
mot
ion
biol
ogic
al m
otio
nbi
olog
ical
mot
ion
biol
ogic
al m
otio
nbi
olog
ical
mot
ion
biol
ogic
al m
otio
nbi
olog
ical
mot
ion
biol
ogic
al m
otio
nbod
ym
otio
n oc
clud
edap
proa
ch m
ovin
g hu
man
non-
biol
ogic
al m
otio
n to
ol m
otio
n to
ol m
otio
n to
ol m
otio
n ra
ndom
mot
ion
rand
om m
otio
n ra
ndom
mot
ion
rand
om m
otio
n ra
ndom
mot
ion
rand
om m
otio
n ra
ndom
mot
ion
rand
om m
otio
n ra
ndom
mot
ion
body
mot
ion
visi
ble
appr
oach
obj
ect
-45
-39
-52
-42
-46
-41
-46
-38
-56
-59
-59
-70
-54
-52
-74
-60
14
15 9 -4
14
11
10 5
0.53
59
47
47
51
59
57
56
53
63
46
44
48
53
52
-42
-56
-64
-69
-37
-41
-46
-59
-44
-49
-68
-66
-40
-61
19
15
10
10
20
21
13
13
2
12
10
0
10
8
0.9
3
-52
-37
-49
8
5
-8
21
25
30
0.2
0
52
34
0 7
47
27
0.1
3
0
.00
0
.00
2008
20
06 b
20
08
2005
20
05
2008
20
07
2006
20
04 b
20
05
2001
20
03
2000
1998
gaze
by
othe
r (p
ictu
re)
gaze
by
othe
r (v
ideo
) ga
ze b
y ot
her
(pic
ture
) ga
ze b
y ot
her
(vid
eo)
gaze
by
othe
r (a
nim
atio
n)
gaze
by
othe
r (p
ictu
re)
gaze
by
othe
r (v
ideo
) ga
ze b
y ot
her
(ani
mat
ion)
ga
ze b
y ot
her
(ani
mat
ion)
ga
ze b
y ot
her
(ani
mat
ion)
ga
ze b
y ot
her
gaze
by
othe
r (p
ictu
re)
gaze
by
othe
r (p
ictu
re)
gaze
by
othe
r (a
nim
atio
n)
view
ing
view
ing
view
ing
+ fo
llow
gaz
e vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g +
mat
chin
gvi
ewin
g
gaze
to
gras
pabl
e ob
ject
ga
ze t
o gr
aspa
ble
obje
ct
gaze
tow
ards
targ
et
gaze
tow
ards
targ
et
gaze
aw
ay fr
om t
arge
t ga
ze a
way
from
sel
f ga
ze to
war
ds s
elf
gaze
tow
ards
sel
f ga
ze to
war
ds s
elf
gaze
tow
ards
sel
f ga
ze
gaze
ga
ze
gaze
sid
eway
s
no g
aze
no g
aze
no g
aze
no g
aze
gaze
tow
ards
targ
et
gaze
tow
ards
sel
f ga
ze a
way
from
sel
f ga
ze a
way
from
sel
f ga
ze a
way
from
sel
f no
gaz
e no
gaz
e no
gaz
e no
gaz
e ga
ze t
owar
ds s
elf
55
50
52
46
60
53
42
55
46
58
45
50 49
-54
-34
-62
-58
-52
-63
-42
-45
-56
-52
-44
-63
-49
17
20
10
12
11
18
21
12
13
8
11
4
-57
-52
-44
-42
-55
-56
-45
-46
-38
-60
-59
-66
-46
-48
-56
53
18
11
20
17
10 8 11 5
-26
-53
-14
10
60
24
48
44
49
0 2 3
46
42
44 0.21
54
53
29
-46
-52
-58
42
39
50 0.21
-33
-52
45
0.07
0.57
30.
140.
93
(con
tinu
edon
next
page)
571F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
Table1(con
tinu
ed)
5. M
otor
Imit
atio
n
Will
iam
s et
al.
Azi
z-Za
deh
et a
l.
Azi
z-Za
deh
et a
l.
Jona
s et
al.
Kos
ki e
t al
. Ia
cobo
ni e
t al
. M
uhla
u et
al.
Mol
nar-
Szak
acs
et a
l. G
reze
s et
al.
Din
stei
n et
al.
Cunn
ingt
on e
t al
. Ja
ckso
n et
al.
Isek
i et
al.
Filim
on e
t al
. G
reze
s et
al.
Bucc
ino
et a
l. V
an d
er G
aag
et a
l. Le
slie
et
al.
Carr
et
al.
Gaz
zola
et
al.
Gaz
zola
et
al.
Hau
k et
al.
Hau
k et
al.
6. G
oal o
f bod
y pa
rt m
otio
n
Schu
botz
et
al.
Gaz
zola
et
al.
Iaco
boni
et
al.
de L
ange
et
al.
Chen
g et
al.
Ham
ilton
& G
raft
on
Ham
ilton
& G
raft
on
MO
VIN
G B
OD
Y PA
RTS
& M
ENTA
LIZI
NG
ARE
AS
7. R
efle
ctin
g on
inte
ntio
n or
une
xpec
ted
mot
ion
Iaco
boni
et
al.
de L
ange
et
al.
Bucc
ino
et a
l. Sh
ane
et a
l. Fa
rrer
et
al.
Bals
lev
et a
l. Ba
lsle
v et
al.
Pelp
hrey
et
al.
Bucc
ino
et a
l. Br
ass
et a
l. D
ecet
y et
al.
Gre
zes
et a
l.
2007
20
06
2006
2007
20
03
1999
20
05
2005
20
03
2007
20
06
2006
20
08
2007
20
03
2004
b
2007
20
04
2003
20
06
2006
20
04
2004
2004
20
07 b
20
05
2008
20
07
2008
20
06
2005
20
08
2007
20
08
2008
20
06
2005
20
04 a
20
07
2007
20
08
2004
a
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
view
ing
/ im
itat
e
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
view
ing
/ im
itat
e vi
ewin
g / i
mag
ine
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
view
ing
/ im
itat
e vi
ewin
g / i
mit
ate
liste
ning
/ m
ime
soun
d lis
teni
ng /
mim
e so
und
read
ing
/ exe
cute
re
adin
g / e
xecu
te
wha
t is
expe
cted
out
com
e?
view
ing
+ im
itat
e vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g vi
ewin
g
atte
nd to
inte
ntio
n at
tend
to in
tent
ion
atte
nd to
inte
ntio
n m
ade
erro
r?
view
ing
+ m
ovin
g +
dela
y?
view
ing
+ w
ho in
itia
ted?
vi
ewin
g +
chan
ge?
view
ing
view
ing
+ in
tend
ed?
view
ing
view
ing
mis
led
abou
t wei
ght?
imit
atio
n im
itat
ion
+ ob
serv
atio
n
imit
atio
n +
obse
rvat
ion
imit
atio
n by
cue
im
itat
ion
by c
ue
imit
atio
n im
itat
ion
imit
atio
n (+
obs
erva
tion
) im
itat
ion
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n im
itat
ion
(cue
) +
obse
rvat
ion
imit
atio
n im
agin
atio
n +
obse
rvat
ion
imit
atio
n (c
ue)
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n im
itat
ion
+ ob
serv
atio
n ac
tion
wor
d +
exec
utio
n ac
tion
wor
d +
exec
utio
n
mot
ion
+ se
quen
ce
inte
ntio
n (b
y co
ntex
t)
inte
ntio
n (b
y co
ntex
t)
extr
aord
inar
y in
tent
ion
gras
ping
food
(w
hen
hung
y)
goal
(ou
tcom
e) o
f mot
ion
goal
obj
ect
of m
otio
n
ordi
nary
act
ion
ordi
nary
act
ion
atte
nd t
o in
tent
ion
inco
rrec
t m
otio
n in
corr
ect
mot
ion
(per
ceiv
ed)
inco
rrec
t m
otio
n (b
y se
lf)
inco
rrec
t m
otio
n (b
y ot
her)
in
corr
ect
mot
ion
inco
rrec
t un
inte
nded
mot
ion
impl
ausi
ble
mot
ion
unju
st h
arm
by
othe
r pr
eten
ded
mot
ion
inco
ngru
ent
mot
ion
no m
otio
n (l
eft
visu
al fi
eld)
no
mot
ion
(rig
ht v
isua
l fie
ld)
obse
rvat
ion
obse
rvat
ion
obse
rvat
ion
over
lear
ned
imit
atio
n no
mot
ion
no m
otio
n (n
one)
no
mot
ion
obse
rvat
ion
no m
otio
n no
mot
ion
no m
otio
n no
mot
ion
no m
otio
n (n
one)
(n
one)
no
mot
ion
no m
otio
n (n
one)
(n
one)
no m
otio
n m
otio
n m
otio
n or
dina
ry in
tent
ion
gras
ping
food
(sa
tiat
ed)
gras
ping
mot
ion
gras
ping
mot
ion
rest
m
eans
of a
ctio
n vi
ewin
g co
rrec
t m
otio
n co
rrec
t m
otio
n co
rrec
t m
otio
n co
rrec
t m
otio
n co
rrec
t m
otio
n or
dina
ry m
otio
n or
dina
ry m
otio
n ac
cide
ntal
har
m
ordi
nary
mot
ion
-34
-42
-41
-51
-40
-30
-51
-45
-46
-46
-48
-47
MEN
TALI
ZIN
G A
REA
SPC
-34
-68
-61
-44
-71
-45
-44
-67
-48
-56
-58
-61
12 6 -8
10 3 46
10
-2
12
10
10
0.43
23
0.14
54 63
63
62
50
59
42
50
38
l-TP
J -61
-36
-36
-37
-48
-31
-58
-40
-58
-5 13
13
21 2 11
0.26
20
20
14
0.43
44
36
56
20 34
50
35
58
56
29
49
26
50
26
0.61
58
44
42
0.43
7
32
32
9
12
24
15
21
22
50
50
49
40
57
29
50
57
56
50
48
18
38
0.57
58
31
0.29
21
54
48
60 8 18
12
24
20
44
26
27
27
52
57
43
37
23
39
32
29 5 59
1.00
29
52
19
-3
16
0.71
15
34 7
22
56
54
2
20
16
20
51
25
48
48
22
23
47
28
44
0.70
11
56
22
-6
-2
16
0.86
46
0
58
15
32
56
30
6
19
-52
-47
-27
-56
-55
-32
-36
-24
-34
-59
-34
-56
-40
-57
-30
-55
-51
r-TP
J
48
62
53
48
56
62
43
50
63
-28
-38
-52
-22
-25
-44
-39
-56
-48
-20
-52
-25
-46
-38
-50
-23
-29
-38
-47
-39
-40
-45
-42
-35
-44
-42
38
28
53
39
37
63
30
51
32
50
34
56
30
40
57
l-PM
C
-53
-38
-56
-33
-46
-40
-26
-46
-34
-48
-32
-46
-28
-54
-42
-28
16
-42
-42
-30
-39
-51
-50
-42
-56
-42
-43
-44
-59
-34
-22
-42
-55
-51
-56
-40
-51
-53
-22
-50
-22
-36
-50
-46
r-PM
C
50
51
53
2
0
-5
0
10
12
5
10
-4
0
7
11
-8
1
-4
0
26
-1
2
11
8
0
7
-4
20
25
5
24
15
14
52
36
38
59
54
50
52
46
63
32
40
55
50
50
48
32
48
34
46
28
48
42
mPF
C
-8
-4
-18
-9
-22
9
7
2
1
4
4
-4
0
15
12
11
8
3
13
-6
2
7
17
8
8
14
13
0
20
25
25
12
26
35
12
36
52
35
48
62
65
¨ ` ` `
MO
VIN
G B
OD
Y PA
RTS
& M
IRRO
R A
REA
S
Stud
yYe
arSt
imul
iIn
stru
ctio
nTa
rget
Cont
rol
MIR
ROR
ARE
AS r-
pSTS
l-aI
PSr-
aIPS
l-PM
C r-
PMC
l-pS
TS
fing
er m
otio
n (n
o ob
ject
) fi
nger
mot
ion
(no
obje
ct)
fing
er m
otio
n (n
o ob
ject
)
fing
er m
otio
n (n
o ob
ject
) fi
nger
mot
ion
(no
obje
ct)
fing
er m
otio
n (n
o ob
ject
) ha
nd /
fing
er m
otio
n (n
o ob
ject
) ha
nd m
otio
n (±
obj
ects
) ha
nd m
otio
n (n
o ob
ject
) ha
nd m
otio
n (n
o ob
ject
) ha
nd m
otio
n (n
o ob
ject
) ha
nd /
foot
mot
ion
(no
obje
ct)
gait
mot
ion
(no
obje
ct)
hand
mot
ion
(rea
chin
g)
hand
mot
ion
(gra
sp)
hand
mot
ion
face
mot
ion
face
mot
ion
face
/ ey
es /
mou
th m
otio
n so
und
of h
and
mot
ion
soun
d of
mou
th m
otio
n ar
m a
ctio
n w
ords
le
g ac
tion
wor
ds
hand
mot
ion
/ sha
pe s
eque
nce
hand
mot
ion
hand
mot
ion
hand
/ he
ad m
otio
n ha
nd m
otio
n ha
nd m
otio
n ha
nd m
otio
n
hand
mot
ion
hand
/ he
ad m
otio
n ha
nd /
leg
mot
ion
fing
er m
otio
n fi
nger
mot
ion
fing
er m
otio
n fi
nger
mot
ion
anim
ated
han
d m
otio
n ha
nd /
leg
mot
ion
hand
mot
ion
harm
to
hand
/ fo
ot.
vide
os o
f peo
ple
lifti
ng b
ox
572 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
WIT
HO
UT
BO
DY
PA
RTS
AN
D M
ENTA
LIZI
NG
AR
EAS
Stud
y
Year
St
imul
i
Inst
ruct
ion
Ta
rget
Cont
rol
MEN
TALI
ZIN
G A
REA
S
8. O
rien
tati
on
Mit
chel
l A
staf
iev
et a
l. A
staf
iev
et a
l. G
iess
ing
et a
l. Le
psie
n an
d Po
llman
n V
osse
l, Th
iel a
nd F
ink
Kin
cade
et a
l. K
onra
d et
al.
(adu
lts)
G
iess
ing
et a
l. Th
iel,
Zille
s an
d Fi
nk
Corb
etta
et a
l. In
dovi
na a
nd M
acal
uso
Todd
, Fou
gnie
and
Mar
ois
Mac
alus
o, F
rith
and
Dri
ver
Dow
nar
et a
l. D
owna
r et
al.
Dow
nar
et a
l.
9. G
oal-
dire
cted
Sha
pe m
otio
n
Fonl
upt e
t al.
Tava
res
et a
l. Ta
vare
s et
al.
Schu
ltz
et a
l. M
orig
uchi
et
al.
Ohn
ishi
et a
l. G
obbi
ni e
t al.
Blak
emor
e et
al.
Mar
tin
and
Wei
sber
g Fa
rrer
and
Fri
th
Aic
horn
et a
l.
10. G
oal-
dire
cted
act
ion
Mar
et a
l. Sp
iers
and
Mag
uire
D
ecet
y et
al.
Van
der
Cru
ysse
n et
al.*
Fe
rstl
and
van
Cra
mon
V
an d
er C
ruys
sen
et a
l.*
Ciar
amid
aro
et a
l. Ci
aram
idar
o et
al.
Ciar
amid
aro
et a
l. Bl
akem
ore
et a
l. (Y
oung
) V
ollm
et a
l. de
n O
uden
et a
l. W
alte
r et
al.
PC l
-TPJ
r-TP
Jl-
PMC
r-PM
Cm
PFC
visu
al d
etec
tion
vi
sual
det
ecti
on
visu
al d
etec
tion
vi
sual
det
ecti
on
visu
al d
etec
tion
vi
sual
det
ecti
on
visu
al d
etec
tion
vi
sual
det
ecti
on
visu
al d
etec
tion
vi
sual
det
ecti
on
visu
al d
etec
tion
vi
sual
det
ecti
on
visu
al t
arge
ts m
emor
izin
g vi
sual
/tac
tile
det
ecti
on
visu
al/a
udit
ory
dete
ctio
n vi
sual
/aud
itor
y/ta
ctile
det
ecti
on
visu
al/a
udit
ory/
tact
ile s
tim
uli
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
anim
atio
ns w
ith
shap
es
mov
ing
joys
tick
vi
sual
sce
nes
acti
on/e
vent
film
/ an
imat
ions
vi
rtua
l tax
i dri
ving
ac
tion
/eve
nt a
nim
atio
ns
acti
on/e
vent
sto
ries
ac
tion
/obj
ect
stor
ies
acti
on/e
vent
sto
ries
ac
tion
/eve
nt s
tori
es
acti
on/e
vent
sto
ries
ac
tion
/eve
nt s
tori
es
acti
on/e
vent
sto
ries
ac
tion
/eve
nt c
arto
ons
acti
on/e
vent
sto
ries
ac
tion
/eve
nt c
arto
ons
dete
ct ta
rget
de
tect
targ
et
dete
ct ta
rget
de
tect
targ
et
dete
ct ta
rget
de
tect
targ
et
dete
ct ta
rget
de
tect
targ
et
dete
ct ta
rget
de
tect
targ
et
dete
ct ta
rget
de
tect
tar
get
(rel
evan
t on
ly)
visu
al s
hort
-ter
m m
emor
y de
tect
targ
et
dete
ct ta
rget
de
tect
targ
et
obse
rve
mot
ion
/ cau
salit
y ju
dgm
ent
seve
ral q
uest
ions
se
vera
l que
stio
ns
view
ing
view
ing
view
ing
seve
ral q
uest
ions
m
otio
n / c
ausa
lity
judg
men
t vi
ewin
g w
ho is
pro
duci
ng m
otio
n?
take
per
spec
tive
of
pass
ive
view
ing
pass
ive
view
ing
who
cau
sed
harm
/ he
lp?
wha
t is
act
or's
inte
ntio
n?
iden
tify
wit
h ac
tors
re
ad
choo
se s
tory
end
ing
choo
se s
tory
end
ing
choo
se s
tory
end
ing
choo
se s
tory
end
ing
choo
se s
tory
end
ing
choo
se s
tory
end
ing
choo
se s
tory
end
ing
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
inva
lid c
ue
low
load
in
valid
cue
ta
sk r
elev
ant
new
cue
no
vel s
tim
ulus
caus
alit
y ju
dgm
ent
soci
al in
tera
ctio
n ju
dgm
ent
atte
nd t
o so
cial
inte
ract
ion
chas
es g
oal o
f tar
get
goal
-dir
ecte
d re
acti
vity
go
al-d
irec
ted
reac
tivi
ty
goal
-dir
ecte
d re
acti
vity
go
al-d
irec
ted
reac
tivi
ty
goal
-dir
ecte
d re
acti
vity
ot
her
othe
r
life
-act
ion
vide
o ot
hers
' tho
ught
s an
d in
tent
ions
in
tent
iona
l act
ion
atte
nd t
o in
tent
ion
unde
rsta
nd in
tent
ions
in
tent
iona
l act
ion
inte
ntio
nal (
com
mun
icat
ive)
in
tent
iona
l act
ion
(soc
ial)
in
tent
iona
l act
ion
(pri
vate
) in
tent
iona
l act
ion
inte
ntio
nal a
ctio
n in
tent
iona
l act
ion
inte
ntio
nal a
ctio
n
valid
cue
va
lid c
ue
valid
cue
va
lid c
ue
valid
cue
va
lid c
ue
valid
cue
va
lid c
ue
valid
cue
va
lid c
ue
valid
cue
va
lid c
ue
high
load
va
lid c
ue
task
irre
leva
nt
sam
e cu
e fa
mili
ar s
tim
ulus
mot
ion
judg
men
t m
otio
n ju
dgm
ent
atte
nd t
o m
otio
n pr
oper
ties
fo
llow
s pa
th o
f tar
get
rand
om m
otio
n ra
ndom
mot
ion
rand
om m
otio
n ra
ndom
mot
ion
phys
ical
rea
ctiv
ity
self
self
anim
ated
vid
eo
no t
houg
hts
phys
ical
eve
nt
phys
ical
eve
nt
no g
oal (
nons
ense
eve
nt)
phys
ical
eve
nt
phys
ical
eve
nt
phys
ical
eve
nt
phys
ical
eve
nt
phys
ical
eve
nt
phys
ical
eve
nt
phys
ical
eve
nt
phys
ical
eve
nt
50
26
27
55
53
36
45
15
-6
9
6
9
17
7
27
60
45
42
26
0.29
25
33
0.18
-44
-38
-39
-42
-44
4
10
0
7
6
40
28
48
31
0.24
40
0.09
59
53
52
44
58
45
51
59
45
53
32
59
64
58
54
56
57
53
48
52
57
47
56
44
50
59
50
53
53
53
56
50
48
53
48
56
-45
-48
-51
-46
-49
-43
-51
-40
-69
-49
-60
-47
-40
-43
-42
-36
-57
-48
-42
-46
-48
-45
-58
-58
-63
-35
-44
-53
-53
-46
-52
-40
-60
-60
-71
-49
27
16
15
19
29
19
26
13
15
30
38
24
32
17
13
24
0.94
23
15
13
14
19
15
19
32
0.73
20
2
21
15
15
19
16
21
22
17
37
14
-42
-32
-58
-59
-54
-51
-56
-61
-57
-49
-48
-45
-52
-50
-45
-56
-45
-53
-42
-48
-53
-52
-52
-50
-48
-61
-50
-50
-57
-57
-52
-39
-67
-65
-67
-46
-68
-57
-68
-57
21
39
28
18
10
0.29
23
17
14
15
17
40
38
0.64
8
25
15
19
37
19
37
25
14
7
8
0
-6
6
8
-6
3
-10
3
-
6
3 -
6
0
-6
-68
-73
-57
-50
-51
-51
-50
-58
-44
-58
-53
-50
-53
-50
-48
-56
46
34
51
0.18
26
22
43
37
50
0.45
49
21
50
39
42
33
33
48
2008
20
06 #
1 20
06 #
2 20
06
2006
20
06
2005
20
05
2004
20
04
2002
20
06
2005
#1
2002
20
01
2000
20
02
2003
20
08
2008
20
04
2006
20
04 #
2 20
07
2003
20
03
2002
20
06
2007
20
06
2008
20
09
2002
20
09
2007
20
07
2007
20
07
2006
20
05
2004
#1
¨`G
reze
s et
al.
Ger
man
et
al.
2004
b
2004
vide
os o
f peo
ple
lifti
ng b
ox
vide
os o
f sho
rt a
ctio
nsm
isle
d ab
out
wei
ght?
vi
deo
com
plet
e?pr
eten
ded
mot
ion
pret
ende
d m
otio
nor
dina
ry m
otio
n or
dina
ry m
otio
n0.
00
-54
-50
-48
-52
0 3 0.
14
59
59-4
3 -5
8 4 14
0.
790.
07
50
3322
20
8 -1
1 0.
36
-2
-9
28
5747
25
0.
79
8 12
-8
-8
10
4
8
1
24
3
2
4
-19
4
0
-3
0
15
-9
6
46
63
56
59
61
56
51
43
40
44
62
52
49
45
59
53
53
37
62
33
38
0.06
20
29
19
25
25
21
-13
0.64
37
14
6
1
30
15
14
11
17
51
8
18
(con
tinu
edon
next
page)
573F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
Table1(con
tinu
ed)
Wal
ter
et a
l.Sa
xe &
Wex
ler
Wan
g et
al.
(adu
lts)
Wan
g et
al.
(chi
ldre
n)
2004
#2
2005
2006
2006
acti
on/e
vent
car
toon
sde
sire
sto
ries
acti
on/e
vent
sto
ries
/car
toon
sac
tion
/eve
nt s
tori
es/c
arto
ons
choo
se s
tory
end
ing
reac
t to
sto
ry e
ndin
gdi
d sp
eake
r m
eant
it?
did
spea
ker
mea
nt it
?
inte
ntio
nal a
ctio
nso
cial
bac
kgro
und
viol
atin
gat
tend
to
face
atte
nd t
o fa
ce
ph
ysic
al e
vent
com
pati
ble
desi
reno
goa
l (re
st)
no g
oal (
rest
)
-6-4
5
59
0.53
50 53 56
-40
-51
-32
2
1
25
4
0.88
-50
-4
44
0.06
6 0 2
49 59 46
-1
3
8
4
0 0
.88
-4
8-5
6-6
4
-66
-30
-54
23
6
14
0.65
50
4
38
0.06
11
. ToM
bel
ief
Mit
chel
lA
brah
am e
t al.
Hyn
es e
t al.
Saxe
& P
owel
lFe
rstl
and
van
Cra
mon
Som
mer
et
al.
Kob
ayas
hi e
t al
.Pe
rner
et
al.
Saxe
, Sch
ulz
& Ji
ang
Gob
bini
et
al.
Saxe
& K
anw
ishe
rSa
xe &
Kan
wis
her
Vog
eley
et
al.
Gal
lagh
er e
t al
.W
akus
ama
et a
l.
2008
2008
2006
2006
2002
2007
2007
2006
2006
2007
2003
#1
2003
#2
2001
2000
2007
belie
f/ob
ject
sto
ries
belie
f/ob
ject
sto
ries
acti
on/o
bjec
t st
orie
sac
tion
/obj
ect s
tori
esac
tion
/obj
ect s
tori
esac
tion
car
toon
sac
tion
/obj
ect s
tori
es/c
arto
onac
tion
/obj
ect s
tori
esac
tion
/obj
ect s
tori
esac
tion
/obj
ect s
tori
esac
tion
/obj
ect s
tori
esac
tion
/obj
ect s
tori
esac
tion
/obj
ect s
tori
esac
tion
sto
ries
/car
toon
sac
tion
/eve
nt c
arto
ons
seve
ral q
uest
ions
seve
ral q
uest
ions
seve
ral q
uest
ions
read
iden
tify
wit
h ac
tors
acti
on a
ctor
exp
ecte
d?se
vera
l que
stio
nsse
vera
l que
stio
nsse
vera
l que
stio
nsse
vera
l que
stio
ns
one-
back
mat
chin
g se
vera
l que
stio
nsse
vera
l que
stio
nsse
vera
l que
stio
nsw
as s
peak
er a
ppro
pria
te?
true
bel
ief
true
bel
ief
true
bel
ief
true
bel
ief
true
bel
ief
fals
e be
lief
fals
e be
lief
fals
e be
lief
fals
e be
lief
fals
e be
lief
fals
e be
lief
fals
e be
lief
fals
e be
lief
fals
e be
lief
iron
y (f
alse
com
mun
icat
ion)
true
phy
sica
l loc
atio
ntr
ue p
hysi
cal l
ocat
ion
phys
ical
app
eara
nce
phys
ical
app
eara
nce
unre
late
d ev
ent
true
bel
ief
scra
mbl
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574 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
Table 2
Task Category N PC l-pSTS r-pSTS l-TPJ r-TPJ l-aIPS r-aIPS l-PMC r-PMC mPFC Cochran Q
Moving Body Parts
1. Execution of hand motion 2. Body part motion3. Whole-body motion4. Gaze5. Mirror system6. Goal of body part motion Kruskal-Wallis ANOVA Kruskal-Wallis ANOVA (1, 2, 5 & 6 only)
7. Reflecting on intention8. Orientation9. Goal-directed Shape motion10. Goal-directed action11. ToM belief12. Morality Kruskal-Wallis ANOVA Kruskal-Wallis ANOVA (9 to 12 only)
2445151423 7
141711171515
0.130.310.530.570.430.140.0240.096
0.000.000.180.290.130.07
——
0.130.380.930.930.260.43
<0.0010.138
0.000.180.360.350.270.07
——
0.96 0.51 0.00 0.07 0.61 0.43 < 0.001 <0.001
0.71 0.49 0.00 0.21 0.57 0.29< 0.001 0.235
0.54 0.76 0.20 0.14 1.00 0.71<0 .001<0.007
0.540.600.130.210.700.860.0010.227
< .001< .001< .001< .001< .001 0.037
Reflection on Goal or no Body Parts
0.140.290.640.650.670.800.0020.763
0.790.940.730.880.800.670.4210.513
0.070.240.090.060.130.07
——
0.360.290.180.060.130.00
——
0.040.070.070.070.090.00
––
0.170.040.070.070.040.00
——
0.250.040.200.140.000.00
——
0.210.240.180.000.130.13
——
0.360.180.180.060.070.07
——
0.790.060.640.880.870.87
<0.001 0.329
< 0.001< 0.001 0.002< 0.001< 0.001< 0.001
0.080.110.070.000.260.14
——
0.000.180.450.530.600.470.0050.865
Note. Cell entries denote the proportion of studies where activation in that region was found. The cell entries of the Kruskal–Wallis ANOVA and Cochran Q (in italics) refer to thesignificance level p of these tests. These tests involve only the regions of interest, indicated in yellow. For tasks 7 to 12, the Cochran Q also involves the PMC.
575F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
This is consistent withmany neuroimaging studies that demonstrate arole of the aIPS in coding for various object properties and affordances(see Tunik et al., 2007). Note that these results are somewhatinconsistent with the conclusions by Morin and Grèzes (2008), whofound an effect of the presence of a goal object on the activity of thePMC (BA 6), while here, this effect appears for the aIPS rather than forthe PMC.
3. Whole-body motion: Movements of a whole-body selectivelyrecruit the posterior part of the superior temporal sulcus (pSTS).These activations are mostly lateralized to the right hemisphere (53%vs. 93%, pb .05). It is important to note that fMRI responses to whole-bodymovement have been shown not only with films of human actorsbut also with robots that mimic human movements and also totemporarily occluded movement as well as to movements displayedwith point lights with only a few small dots at the major human jointswhile all the rest is invisible. Our familiarity with human andbiological movement makes these moving light dots so compellingthat they are perceived as natural movements. Note that these aresimple and familiar movements like walking and turning, not complexand specialized body movements such as in dancing (Calvo-Merino etal., 2005, 2006; Cross et al., 2006).
4. Gaze: Eye motion selectively engages the posterior part of thesuperior temporal sulcus (pSTS). These activations are also lateralizedmostly to the right hemisphere (57% vs. 93%, pb .05). The analysisreveals conflicting results, that is, it shows most activation for gazeeither directed to or averted from the observer. However, studies thatcontrolled the amount of eye movement and head position (Pelphreyet al., 2004b) suggest that gaze directed to the observer is associatedwith the most processing as it reflects mutual attention (George andConty, 2008). Like whole-body motions, motions of the eyes do norecruit the aIPS or the PMC, which suggests that classic mirror neuronsare not typically involved.
5.Motor imitation: As described earlier, to delineate the location ofthe mirror system in humans, researchers typically sought brain areascommonly activated by action observation and execution (i.e.,imitation) as opposed to static positions. Or they tried to identifyareas that were more strongly recruited during imitating than duringviewing movements because imitation involves executing in additionto viewing. Imitation was elicited either by explicit instruction orexternal cues that generate the same movement (e.g., a dot indicatingwhich finger to lift up). As can be seen in Table 1, many studies reportactivation of the aIPS (61% vs. 57%, ns) and the PMC (100% vs. 70%,pb .01) in both hemispheres. As in the studies of the mere observationof body-part motions, activation in these areas occurs regardless of
whether the input was visual, auditory or verbal (with the latterformats at the bottom rows of Task 5).
6. Goal of body-part motion: So far, all of the studies have confirmedthat the aIPS and the PMC respond to the observation of someoneelse's actions with the exception of whole-body and eye motions. Thissuggests that the mirror system subserved by these areas mayparticipate in the understanding of an action in terms of its immediategoal (e.g., taking a cookie). It does not specify whether this system alsocodes higher-level goals of actions such as task goals that reflect the“why” of an action (e.g., to prepare a snack). This could be clarified byvarying the task goal of actions bymanipulating their context (e.g., thegoal of having breakfast versus cleaning up as signaled by a table thatis either just set or messy; Iacoboni et al., 2005) or their plausibilitywith respect to the goal object (e.g., putting a coffee cup to one's ear;de Lange et al., 2008). When a task goal is ambiguous or varied bymanipulation of the context, the PMC should become more activesince this area is assumed to search for alternative goals that couldaccount for the observed action. Other researchers have takenadvantage of the principle of repetition suppression, that is, thereduction in brain activation in response to the repeated presentationof a stimulus. These studies varied the repetition of the hand motion(e.g., moving the lid of a box) or of its task goal (e.g., moving the lid toopen or close the box) to isolate the effect of the task goal (Hamiltonand Grafton, 2006; 2008). We identified all the available studies andlisted them under Task 6. The PMC seems to be recruitedmore (71% vs.86%, ns) than the aIPS (43% vs. 29%, ns), and this difference approachessignificance in the right hemisphere, p=.052. Although it is theventral part of the PMC (inferior frontal gyrus) that is most oftenactivated, this is most likely because all of the studies involve handmotions. The repetition suppression studies demonstrate that taskgoals (e.g., open a box; Hamilton and Grafton, 2008) activate both thePMC and aIPS, whereas understanding the action in terms of theimmediate goal (e.g., grasping an object; Hamilton and Grafton, 2006)affects only the aIPS. If this study is removed (so that only studies thatmanipulate higher-level task goals remain), the PMC is involved in allof them.
Summary and discussion
This review supports the contention that the aIPS and PMC arecrucially involved in the mirror system. Our analysis strongly suggeststhat what triggers these areas foremost is input onmoving body parts.The activation pattern during observation and mirror tasks (Task 2and 5) is consistent with the notion that the aIPS and the PMC process
576 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
immediate goals for action understanding. When higher-order taskgoals are made more salient (Task 6), the activation pattern isconsistent with the idea that the PMC represents task goals as well.That the PMC codes task goals is in line with other evidence showing
A
-60
-40
-20
0
20
40
60
80
-120 -100 -80 -60 -40 -20 0 20 40 60 80
Execution of hand motion Body part motionMotor Imitation Goal of body part motionWhole-body motion Gaze
aIPS
pSTS
PMC
8
C
-60
-40
-20
0
20
40
60
80
-120 -100 -80 -60 -40 -20 0 20 40 60 80
Reflecting on intention or unexpected motion
PMC
mPFC
TPJ
8
E
-60
-40
-20
0
20
40
60
80
-120 -100 -80 -60 -40 -20 0 20 40 60 80
Orientation Shape motionGoal-directed action ToM beliefMorality
TPJ
mPFC
8
the activation of this region during observation of hand movementsevenwhen the specific details of the movement are outside the motorvocabulary of the observer: hand actions for participants bornwithouthands (Gazzola et al., 2007a) and robotic actions for typically
B
-60
-40
-20
0
20
40
60
80
-120-100-80-60-40-2002040600
Execution of hand motion Body part motionMotor Imitation Goal of body part motionWhole-body motion Gaze
pSTS
aIPS
PMC
D
-60
-40
-20
0
20
40
60
80
-120-100-80-60-40-2002040600
Reflecting on intention or unexpected motion
TPJPMC
mPFC
F
-60
-40
-20
0
20
40
60
80
-120-100-80-60-40-2002040600
Orientation Shape motionGoal-directed action ToM beliefMorality
mPFC
TPJ
577F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
developed participants (Gazzola et al., 2007b). These results aregenerally in line with the mirror hypothesis that observed actions areautomatically matched with one's own behavioral repertoire (Rizzo-latti et al., 2001). Consequently, to extract the goal from an action ormotion, no high-level “simulation” or putting oneself “in the shoes” or“mind” of the other is needed.
Interestingly, the PMC (but not the aIPS) seems to reveal a roughsomatotopic organization much in line with the classic homunculusof the sensory and motor system, with foot motions at superiorareas, mouth motions at inferior areas, and other body parts in bet-ween. This was suggested by a non-parametric Gamma correlationbetween a mouth vs. foot arrangement and the z-coordinates at theright (or if absent, left) PMC across Tasks 2 and 5, which approachessignificance, r=.51, pb .07. This somatotopic organization has beendemonstrated for auditory input as well (Gazzola et al., 2006; Galatiet al., 2008).
In contrast, motions of whole bodies or eyes do no recruit the aIPSor the PMC, which suggests that classic mirror neurons are nottypically involved. This seems plausible because familiar motions likewalking, turning and gazing typically do not have an object to act onthatmight reveal the underlying goal of the action. Instead, they signalto the observer the orientation and objective of the actor, which mayreveal more about the actor's goals and intentions than a match withthe observer's behavioral repertoire. In support of this reasoning, ithas been found that a gaze induces an automatic shift of the observer'sattention in the seen gaze direction as revealed, for instance, byPosner's orienting task, in which the gaze is used as the centralattention cue (Driver et al., 1999; Langton et al., 2000). Pointing afinger has the same effect (Materna et al., 2008). A gaze elicits evengreater pSTS activation during identification of its target than does aphysical cue (e.g., an arrow; Hooker et al., 2003). Note that anexception should be made for emotional body and gaze motions,which may convey a great deal of information. The same goes forspecialized movements like dancing, which of themselves are thefocus of observation and imitation. A gaze can sometimes recruitmirror areas when the gaze points to graspable objects that haveassociated motor goals (Pierno et al., 2006b; no such effect was foundby Pierno et al., 2008). These special cases are not studied here.
To conclude, one observation clearly stands out. The mirror systembut not the mentalizing system, is activated when moving body partsare observed (Tasks 1 to 6). This suggests that the mirror andmentalizing systems are quite independent for this type of input.
Information on moving body parts and mentalizing
However, even when moving body parts are observed, thementalizing system becomes active under some conditions. In thissecond section, we now turn to the set of studies that marks atransition from the mirror to the mentalizing system. Table 1 lists thecoordinates of thementalizing regions and of the PMC that is assumedto code the goal of actions.
7. Reflection on intention or unexpected motion: What is the role ofdeliberation about task goals or the intentions of an actor? In somestudies, participants are instructed to pay attention to the “intention”of the actors (de Lange et al., 2008, p. 456; Iacoboni, 2005, p. 534) or toactions that “were intended” (Buccino et al., 2007, p. 212). In otherstudies, they see humanmotions that are unusual (e.g., turning a lightswitch with the knee; stumbling while walking), pretended (e.g.,
Fig. 3. The studies andmajor areas involved in the mirror andmentalizing systems placed in aanterior reflects the anatomical y-axis, and inferior–superior reflects the anatomical z-axis. Esensory and verbal input is propagated to the aIPS and further to the PMC where it is comparethe pSTS; right and left hemisphere, respectively. Body-part motions include only studies wbetween the mirror and the mentalizing system for reflections on intentions or unexpected aand mPFC (mentalizing); right and left hemisphere, respectively (the peaks at the mPFC, msensory and verbal input is propagated to the TPJ for goal, belief and morality inferences andshown), right and left hemisphere, respectively (the peaks at the mPFC are identical in bot
miming to lift something) or otherwise inconsistent within a givencontext. As can be seen in Figs. 3C, D, in this case, either the right TPJ(79%) or the mPFC (79%) is recruited, or both are. The aIPS and thePMC are activated in only one third of the studies.
Summary and discussion
Somewhat unexpectedly, even when biological movement isobserved, the mentalizing system is activated in Task 7. What causedthis? First, unlike Task 6, the participants were explicitly instructed todeliberate on the intentions of the actors. Second, unlike somebehaviors from Task 6 that are performed in a normal fashion but havea somewhat unusual goal (e.g., holding a cup with the hand up toone's ear; see de Lange et al., 2008), the actions in Task 7 themselvesare atypical or unfamiliar, so that there is no template in one'sbehavioral repertoire to match them with (see also Calvo-Merino etal., 2005, 2006; Cross et al., 2006). This renders the mirror systeminadequate and requires extensive thought about the “why” of theaction. As a consequence, thementalizing system takes precedence. Asnoted by Brass et al. (2007, p. 2120) “inferring the purpose of anunusual action and the reason why it is performed in an implausiblecontext necessitates a great deal of active inferencing to evaluate theefficiency of the action in relation to its situational constraints”. Takentogether, when a deliberative focus is triggered either by theattentional focus of the perceiver (exogenous to the stimulus) or bysalient properties of an inconsistent or unexpected action (endogen-ous to the stimulus), the mentalizing system is activated.
It should be noted that there is an alternative explanation for thelow-level of activation of the aIPS and the PMC. This may be due to thetight control of behaviors and the low-level task goals across allconditions in some studies. For instance, in the study by Brass et al.(2007), the actors always engaged in the same behavior involving thesame task goal and goal object (switching on the light with their knee)but under different contextual conditions so that some behaviors wereplausible (while holding a stack of books) whereas other were not(without books). Consequently, in comparisons between theseconditions, potential activation in these areas is cancelled out.
To conclude, when the mirror system fails even when observingmoving body parts (presumably because the action does not allow a“match” with one's own behavioral repertoire, Task 7), the mentaliz-ing system dominates brain activity (while the PMC remains some-what active in some studies). This suggests that the mirror systemmay fail under many other conditions such as when the behavior isdescribed (verbally) at a more abstract level, or when the action leadsto multiple goals and more mental processing is required for selectingonly one of them. To better understand the distinction betweenmirrorand mentalizing systems, we now turn to studies that clearly involvethe mentalizing system.
No information on moving body parts
When observers have no information at their disposal on movinghumans or body parts (i.e., when they read short stories about humanactions), the mentalizing rather than the mirror system is recruited.This third section of the meta-analysis reviews all the mentalizingareas of interest, including the precuneus (PC), the temporo-parietaljunction (TPJ) and the medial prefrontal cortex (mPFC). We first focuson the orienting function of the TPJ and then turn to a large set of fMRI
n x–y–z Talairach atlas. Left–right (not shown) reflects the anatomical x-axis, posterior–ach peak can be identified via the y–z coordinates in Table 1. (A, B) The mirror system:d with own action schemas and associated goals. Whole-body and gaze motions recruitith object manipulation and appropriate (no-motion) controls. (C, D) The interactionctions: the input is propagated to the TPJ (mentalizing) and further to the PMC (mirror)arked with a small bullet, are identical in both views). (E, F) The mentalizing system:further to the mPFC for inferences on traits or reflective reasoning (the precuneus is noth views).
578 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
studies in which inferring the actor's momentary intentionality is amain part of the observers' task. Figs. 3E, F depict the coordinates ofactivity in response to tasks that involve orienting to a novel externaltarget (Task 8). It also gives the coordinates of tasks involving theinference of intentionality of external targets while the perceiverobserves movements of shapes (Task 9), predicts the end-state ofnarrated behaviors (Tasks 10), or understands an actor's beliefs aboutthe desired outcome or the morality of behavior (Tasks 11–12). As canbe seen in Table 1, mostly verbal material like short stories orsentences is used in these tasks but also more visual material likecartoons. For simplicity's sake, we use the terms “verbal”, “stories” and“narratives” to imply the absence of information about moving bodyparts in the remainder of this section.
In line with the assumed primary role of the TPJ in these tasks (seeIntroduction), Kruskal–Wallis ANOVAs in Table 2 show a consistentpattern of activation in the right hemisphere, which does not differsignificantly across these tasks, with the highest amount of activityoverall in the right TPJ. When limited to the last four classicmentalizing tasks (Tasks 9–12), all regions show a consistent patternof activation, with the highest activation in the TPJ bilaterally and inthe mPFC and, to a lesser extent, in the PC.
8. Orientation: To study orientation, researchers typically usePosner's cued target-detection task described earlier. As can be seen inTable 1, a great majority of these studies show involvement of the TPJ,especially in the right hemisphere (94%). The TPJ is not active whileonly the cue is present (before the target is shown; see Corbetta et al.,2000, 2002), so orientation to an external target at a novel place iswhat drives this effect. This function is multimodal since the TPJ is alsoinvolved when the cue and the target are presented in a tactile (e.g.,air puffs) or auditorymanner.While all these tasks use stimuli that aredevoid of social content, a recent study documented that the right TPJis also responsive to spatial orientation between persons (e.g., “Petersits in front of Nina”; Abraham et al., 2008), which appears to confirmthe importance of the right TPJ in orientation of humans. Note that,given the large overlap withmentalizing studies discussed next (Tasks9–12), many orientation coordinates in Figs. 3E, F are obscured by thecoordinates of these latter studies.
9. Goal-directed shape motion: Intentionality is immediatelyevident when animations show interactions of simple shapes likesquares or triangles that move as a consequence of non-mechanicalcausation at a distance (see the classic study by Heider and Simmel,1944).When a shape is followed by another object or seems to react toits movement, this is perceived as driven by internal goals. Incomparison to random movements, these shape animations result inTPJ activation in both hemispheres (81%). They are so compelling thatthey even create greater activity in the TPJ than do goal-directed handmanipulations of an object (cup, hammer, telephone, etc., Ohnishi etal., 2004). The activation in other mentalizing areas (e.g., mPFC andPC) is less systematic than the activation of the TPJ.
10. Goal-directed action: In these studies, participants are asked toidentify the likely or desired end-state of a story (e.g., a prisonerescaping after breaking his cell's window) in comparison with merephysical consequences (e.g., a ball hitting a child). These tasks requireidentifying the implied task goal or intention of an action withoutnecessarily understanding the actor's own beliefs. The implicit goalinferences in these studies lead to activation at both hemispheres inthe TPJ (100%), the mPFC (88%) and the PC (53%). It is important tonote that the TPJ is not simply engaged by orienting to people or theiractions, because several studies included a control condition withhuman agents who were observing rather than acting (Völlm et al.,2006), who were acting but were rendered cartoon-like rather thanveridically (Mar et al., 2007), or who acted consistent with expecta-tions rather than violating them (Saxe and Wexler, 2005). Interest-ingly, a recent study (Ciaramidaro et al., 2007; see Table 1) suggests adistinction between intentions along a dimension of increasing socialinteraction, starting with private intentions of the actor only, moving
on to social prospective intentions (preparing future interactions withothers) and ending with conversational interactions. These authorsfound that an increasing number of mentalizing areas was involved astasks progressed along this social intentionality dimension. The rightTPJ and precuneus were activated in the comprehension of all threedifferent types of intention; the mPFC was also activated in pros-pective social intention; and the left TPJ was activated exclusively inthe processing of communicative intention. Given that most studies inTask 10 combine private and social (i.e., prospective) intentions, moreempirical evidence is needed to corroborate this important distinction.
11. ToM belief: In theory of mind (ToM) tasks, the participants mustunderstand that the protagonist acted the way he or she did becauseof a distinct goal he or she had in mind. In tasks that involve a “true”belief, the observer simply needs to identify the protagonists' belief orgoal, presumably on the basis of one's own belief given a similarsituation. However, the ToM capacity becomes most evident whenone's own and other's beliefs diverge in “false” belief tasks, asdescribed earlier. Recent studies have used carefullymatched controls,such as stories involving photos that are “false” in the sense that theybecame outdated after some critical event (Saxe et al., 2006). Table 1shows that many of these tasks lead to increased activation in bothhemispheres in the TPJ (87%), the mPFC (87%) and the PC (60%).
12. Morality: When judging whether or not people acted justly orfairly, we often take their intentions and motives into account. Whenconfronted with a moral dilemma, we seem to base our judgments oneffortful action or intentions to act rather than on a logical analysis ofdeath count or harm estimates. This emphasis on intentionality is alsoseen in the law, for instance, in the distinction between premeditatedmurder and accidental manslaughter. The moral tasks in Table 1involve dilemmas with different levels and types of moral injustice(e.g., commission of unjust actions versus omission of just actions,whether or not a person is critically involved, whether or not a moraldilemma is left open, or whether or not the wrong-doing has beencommitted). As can be seen, moral, personal or norm-violating storieselicit more activation than do nonmoral, impersonal or normalactivities in both hemispheres at the TPJ (93%), the mPFC (87%) andthe PC (47%). Note again that the TPJ is not engaged by orienting topeople or their actions as such, as these are part of both theexperimental (personal) and control (impersonal) conditions (e.g.,Greene et al., 2004).
Summary and discussion
The studies in this review support the contention that thementalizing system is crucially involved in understanding the intentof a social agent, typically at the level of a task goal or generalintention. Unlike understanding an action on the basis of body-partmotions, which recruits the mirror system, goal-directed socialhuman behavior devoid of information about body parts recruits thementalizing system. Sometimes, the mentalizing system is invokedwhen observers perceive motions at a relatively low-level ofdescription (e.g., shape motions), while other studies report thiscapacity at a non-perceptual and abstract level (e.g., verbal storiesimplying goals, beliefs and morality). We suggested that the TPJ is thecore area in goal inferences, and this was confirmed by its largeactivation overall. We found that the TPJ is not simply engaged byorienting to people or their actions alone, although this may be part ofa larger process of goal identification. The engagement of the PC mayreflect additional processing for representing complex goal contexts,and the engagement of the mPFC may be indicative of either(additional) deliberative reasoning or trait inferences that are madespontaneously (see Van Overwalle, 2009; for a review, Uleman et al.,2005). The present data are not informativewith respect to the precisefunctionality of these two regions.
Our central question, however, was whether there is any evidencefor a direct supporting role of the mirror system during mentalizing
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tasks. Apparently not. In none of the mentalizing studies was thePMC systematically activated. If the PMC is crucial for identifyingtask goals, one should certainly expect involvement of this areaespecially during the explicit scrutinizing and searching for inten-tions. Two studies without body parts were found in which par-ticipants were asked to identify “goals” (Van der Cruyssen et al.,2009) or “motivations” (Ferstl and van Cramon, 2002, p. 1601), but inneither was the PMC recruited. Taken together, the present datasuggest that, in the absence of biological motions, the mirror systemis not activated and does not aid the mentalizing system in detectingintentionality.
Conclusions
This review covers more than 180 fMRI studies on humanunderstanding of intentionality as well as about 40 fMRI studiesinvolving potentially related functionalities (i.e., behavior executionand orientation). The analysis suggests a clear conclusion: the mirrorand mentalizing systems are two distinct systems, each specialized inthe processing of observed sensory or verbal information about otherpersons but based on different inputs. The mirror system is recruitedwhen moving body parts are observed. The mentalizing system isrecruited when no such input is available. Except when deliberatingon higher-level task goals or intentions (“why”) of observed biologicalactions, often as a result of instruction or anomalous performance(Task 7), these two systems are never concurrently active. Thissuggests that neither system aids or subserves the other. Rather, theyare complementary. This conclusion is contrary to suggestions that themirror system might aid the mentalizing system to inferringintentions of others (e.g., Agnew et al., 2007; Blakemore et al., 2004;Decety and Chaminade, 2003; Keysers and Gazzola, 2007; Uddin et al.,2007; Van Overwalle, 2009). From the principle of theoreticalparsimony, this seems surprising. However, from an evolutionaryperspective, the concept of social understanding might simply be toogeneral. Instead, adaptations reflect the specificity of evolutionaryselection pressures resulting in a number of domain specific circuits –amirror andmentalizing system – each designed to optimize differentaspects of social processing.
Our suggestion that these two systems each are specialized indetecting different aspects of human behavior is based on research inwhich tasks were often designed to be as pure as possible, that is,perceived motor behavior with little social content for testing themirror system as opposed tomore abstract descriptions in the absenceof any motion for probing the mentalizing system. Although suchisolated tasks are necessary to specify the essence and delineate thelimits of each system, they do not approximate the kind of socialinformation that perceivers use as input in real-world interactions.Thus, we do not at all suggest that these two systems are disconnectedin real-world social inferencing. Quite on the contrary, in judgingothers, we often rely on both a target's motor intentions and explicitverbal information (e.g., observing the target of a gossip and hearingharsh words spoken about him or her). How these two types ofinformation interact is still a new area in social neuroscience, one thatwe are only beginning to explore by means of tasks as exemplified byactions that are unexpected and inconsistent (see Task 7). Onequestion for future research is to explore what happens in the socialbrainwhen tasks potentially recruit both systems, but when themotorand the verbal inputs contradict each other. A recent study exploredspontaneous inferences during an interactive real-world task (taxidriving in a virtual world) and found activity predominantly in thementalizing system (Spiers and Maguire, 2006), although the twosystems were not systematically pinned against each other.
Two other caveats should be mentioned before going on. First, thepresent analysis focuses on pre-defined sets of regions. This wasmotivated by the complexity and richness of the fMRI data, but thiskind of analysis may actually miss regions that could be active but
have not been coded as belonging to the two systems. Often re-searchers have a priori hypotheses about the regions of interest andtend to use quite liberal criteria for detecting them. This bias may beaugmented in thismeta-analysis becausewe relied on the researcher'sown thresholds for significance. To avoid this, one might considerincluding other brain regions. However, this should be donewith greatcare. Brain regions outside the two systems may have been activatedbecause task instructions invited participants to elaborate on theiralready made social inferences; not because they are essential forthose inferences. For instance, simply reading trait-implying beha-vioral descriptions tends to activate only the core mentalizing TPJ andmPFC areas, while explicit instructions to infer these traits alsoactivates the PC and other areas (Ma et al., 2009).
A related concern is that despite the considerable overlap betweenthe pSTS and the TPJ, we made a somewhat arbitrary distinctionbetween these regions based not only on anatomy but also on the typeof task involved (see Method section). However, because ourinterpretation of the mentalizing system is based on the concurrentactivation of the TPJ and the mPFC, our main conclusion on theindependence of the mirror and the mentalizing system remains valideven if one would doubt the present definition of the TPJ. Stateddifferently, even if a sharp functional or anatomical distinctionbetween the pSTS and the TPJ would not exist, the results still showa segregation of the aIPS and the PMC mirror areas on the one handand the mPFC mentalizing area on the other hand. Future researchshould explore to what extent the pSTS and the TPJ subservefunctionally segregated or integrated processes of goal inference.
The mirror system
The mirror system is an action understanding system that isengaged when motions from body parts such as fingers, hands, face,and limbs are observed irrespective of the sensory or verbal format ofthis input. The mirror literature posits that these inputs are identifiedat themultimodal STS and are further transmitted to the aIPS (Keysersand Perrett, 2004; Nishitani and Hari, 2002) where the relationshipwith the object or context is specified (Tunik et al., 2007) and to thePMC. During observation, the input in the PMC is compared to one'sown motor repertoire, and when they match, the action's goal isidentified (Rizzolatti et al., 2001). This theoretical account isconsistent with the present analysis, which demonstrated that thepresence of a goal object (e.g., tool) enhances the activity of the aIPS.This effect was not found for the PMC, which fits with the notion thatgoals are encoded in this brain area irrespective of how they areperformed. This challenges the conclusion by Morin and Grèzes(2008) that tools are essential in activating the PMC (Brodmann area6). That the PMC essentially encodes goals associated with body-partmotions becomes most evident when observed goals are extraordin-ary or unusual, and this area is selectively engaged during the searchfor an appropriate goal identification (see Task 6). In terms ofHamilton and Grafton's (2006) goal hierarchy (Fig. 1), most of themanipulations in mirror research reflect mere actions (e.g., reach),immediate goals (e.g., take a cookie), and especially in Task 6, also taskgoals embedded in a context (e.g., prepare a snack). Hence, the mirrorareas seem to code a great variety of goals from low tomoderate levelsin the goal hierarchy.
Some bodily motions do not give rise to mirror activity. First,whole-body motions like walking, gaze and finger pointing elicitorientation reactions in the STS, presumably because mirroring thesemotions has no real functional advantage. However, more articulatedwhole-body motions like dancing, which are observed and imitatedfor esthetic and social reasons, recruit the mirror system when theobservers are expert dancers as regards these moves (Calvo-Merinoet al., 2005, 2006; Cross et al., 2006). Second, motions that areinconsistent or implausible within a given context (see Task 7) recruitthe mirror system less systematically than the mentalizing system,
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presumably because these actions seem to lack an adequate “mirror”template in the motor repertoire with which to match.
In sum, except for these latter cases, the data in this meta-analysisshow a clear and close overlap in activation between execution andobservation of the same action of the same body-part. This is in linewith the matching account of the mirror system that holds that “weunderstand actions when we map the visual representation of theobserved action onto our motor representation of the same action”(Rizzolatti et al., 2001, p. 665). Moreover, the present analysisbroadens its role to other sensory (auditory) and semantic (verbal)input formats. However, as noted in the Introduction, overlappingactivation only provides indirect evidence for identical functionality.Recently, researchers have sought more direct evidence for the jointneural coding of perceived and executed motions by using the noveltechnique of classifying activation patterns in overlapping brain areas.That is, instead of considering only the global activation in a brain areaunder different conditions, patterns of individual voxels ranging fromlow to high activation in one condition are used to predict patterns ofactivation in another condition. Etzel et al. (2008) found that, when apattern classifier learns to discriminate between the activationpatterns in the PMC caused by the sound of hand or mouth actions,it can correctly classify the activation patterns of executed hand ormouth actions, respectively, in the PMC. This points to similar, cross-modal audiomotor neurons coding for observed and executed actionsin the PMC, which is consistent with mirror theory. In contrast,Dinstein et al. (2008; 2007) found that the aIPS has different neuralpopulations for visual and motor actions and lacks cross-modalvisuomotor neurons. More research is needed to confirm theseapparently diverging findings about the mirror functionality in theaIPS and PMC.
The mentalizing system
In sharp contrast, the mentalizing system is recruited when peopletry to infer the intentionality of others in the absence of detailedinformation on biological motions of social actors, that is, when itreceives input on motions of geometric shapes or on more abstractbehaviors, beliefs or morality of others (most often via verbal stories).Theoretical accounts of this mentalizing system are less developedand need to be further clarified. The present meta-analysis, however,provides additional evidence consistent with the proposal by VanOverwalle (2009) that the major functionality of the TPJ is to analyzethe directionality of behavior in relation to its expected end-goal.Thus, it is engaged not only during orientation to relevant targets atthe visuo-spatial level, as revealed by Posner's cue reorientation task,but also during identification of the end-state of described behaviorsat amore abstract semantic level. This capacitymay be present at birthand may develop during joint orientation and attention between aninfant and a caretaker, when a child learns that following theorientation of the caretaker often results in finding new or interestingobjects and people (Redcay, 2008) and also learns how and why (i.e.,goals) these objects and people move. Obviously, more research isneeded to elucidate the precise functionality of the TPJ. Perhaps, therole of the TPJ can be better understood by providing explicitprocessing instructions, by comparing different contexts, or by furtherexploring the parallels with non-social functions in this brain area.
Still unclear is the function of the precuneus in the mentalizingsystem. This area was involved to some degree in all the mentalizingtasks, except during observation of geometric shapes. Perhaps its roleis to retrieve situations encoded in memory to match them with thecurrent context in order to select or infer an appropriate action andgoal. Behavioral studies demonstrate that an environment such as alibrary or restaurant may raise environment-specific social norms(e.g., being quiet, using table manners; Joly et al., 2008; Aarts andDijksterhuis, 2003). It is thus quite plausible that the mentalizingsystem takes advantage of contextual information, which might re-
quire the PC for identifying the situational structure and context(Speer et al., 2007) or retrieving episodic context information(Cavanna and Trimble, 2006). The precuneus was not analyzed inthe earlier meta-analysis by Van Overwalle (2009), but obviously ithas an important, although not necessarily systematic, role inmentalizing. Determining its precise role in context matching is anobjective for further research. It is possible that this role is rathersubserved by the mPFC by extracting relevant information on socialscripts (Van Overwalle, 2009) or on rewarding action-goal outcomes(Matsumoto and Tanaka, 2004).
In sum, the results of thismeta-analysis are broadly consistentwiththe theoretical account of the mentalizing system proposed in themeta-analysis by Van Overwalle (2009). However, we found nosupport for the possible auxiliary role of the mirror system. It isinteresting to note that the present findings do not challenge otherimportant conclusions from that earlier analysis: the mPFC ispreferentially involved in the processing of more enduring traits andattributes of persons as well as of groups (e.g., social scripts), and noother executive functions that recruit the medial and lateral areas ofthe PFC (e.g., response inhibition, episodic memory, dual-attention,workingmemory) are systematically engaged during social inferences.
Remaining questions
As should be obvious from the conclusions above, there are stillsome unresolved issues that need clarification. Here is a brief list of anumber of them.
A transition from mirror to mentalizing system?
We have seen that, even when information is available on movingbody parts, the mentalizing system is recruited when observersexplicitly attend to goals or when actions are unexpected andinconsistent (Task 7). This points to two possible reasons why thementalizing system is recruited for understand human biologicalmotion under these circumstances.
First, an inconsistent or anomalous movement might be outsidethe perceiver's repertoire of familiar movements, so the mirror systemcannot be of help. To resolve this, inferences of higher-level goals (e.g.,“why did the actress fall?”) or other attributes (e.g., “was shedepressed?”) seem to be needed, which are outside the scope of themirror system. Second, when the perceiver reflects on a high-levelintention of an action, this might necessarily engage the mentalizingsystem. It is possible that the mirror system is recruited for automaticlower-level goal interpretation (from pure actions to task goals, seeHamilton and Grafton, 2006; Fig. 1) and the mentalizing system forreflection on the higher-level goals (from task goals to more generalintentions). A lack of systematic information on goal levels in thestudies reviewed here precludes us from drawing any conclusion onthis interesting possibility. A decisive test could be the activation ofthe mirror system in verbal stories involving simple and immediateaction goals (without explicit or easily imaginable body parts or toolsto avoid contamination from “perceptual” input). Studies manipulat-ing alternative levels of goal pursuit, perhaps in terms of their socialinteractive implications as applied by Ciaramidaro et al. (2007), arealso clearly needed.
A related question concerns the extent to which the two systemsrespond to sensory and verbal input alike. Although current researchtraditions may suggest that the mirror system is more easily recruitedby visual material and the mentalizing system by verbal material, thismay have been a consequence of mere convenience and of the historyof past research. More evidence is needed to answer this question.
Even if so, perhaps there are other conditions in which the mirrorsystem does not provide an answer but in which the mentalizingsystem does. For instance, two studies by Brass and colleagues foundthat thementalizing system is recruitedwhen one actively inhibits the
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imitation of someone else's behavior (Brass et al., 2001; Brass et al.,2005). These authors suggest that the mentalizing system controlsand prevents imitative responses that are automatically triggered bythe mirror system by distinguishing between self- and other-generated actions. Further exploring the conditions in which themirror system is dominated or interrupted by the mentalizing systemwould advance our knowledge on the breadth and functionality ofeach of these systems.
Other social inferences
Another way to investigate the role and breadth of the mentalizingsystemwould be to explore other social inferences and processes thathave been reported in the social psychological literature but that havebeen somewhat neglected in social neuroscientific research. To namebut a few: what is the role of spontaneous versus explicit processing ofother social inferences besides goals, such as the other's traits? RecentERP research reveals that early and automatic goal inferences alwaysinvolve the TPJ, while later and less automatic trait inferences involvethe mPFC, although the TPJ is recruited more when trait inferences aremade spontaneously (Van Duynslaeger et al., 2007; Van der Cruyssenet al., 2009). What are the potential differences in timing and areas ofthe brain for true and false beliefs and morality judgments when theyare processed implicitly or explicitly? Other social decisions form anintrinsic part of our life but have seldom been investigated such as (a)the role of ulterior (and usually hidden) motives and how they differfrom overt intentions, (b) the role of attitudes and persuasive com-munication, (c) the distinction between causality focusing on motivesand traits of others versus reasons or situational constraints (i.e.,situational inferences, e.g., Ham and Vonk, 2003), (d) the effect ofemotions and (e) the impact of stereotypes on individual inferences ofothers' goals and traits. Research by Harris and Fiske (2006) andMitchell (2009) suggests that the mentalizing system is not recruitedwhen we stereotype others as members of unimportant out-groups,which suggests that we process these people as infra-human objects.Exploring these neglected issues with neuroscientific tools may proveto be crucial in delineating the conditions in which the mirror andmentalizing system are recruited for understanding other humansand, as such, become instrumental in promoting social progress andchange.
Acknowledgments
Kris Baetens is a Ph.D. fellow of the Research Foundation – Flanders(FWO). We thank Marcel Brass for his suggestions about an earlierversion of this manuscript.
References
* refers to studies in the meta-analysis of Table 1.Aarts, H., Dijksterhuis, A., 2003. The silence of the library: environment, situational
norm and social behavior. J. Pers. Soc. Psychol. 84, 18–28.⁎Abraham, A., Werning, M., Rakoczy, H., von Cramon, D.Y., Schubotz, R.I., 2008. Minds,
persons, and space: an fMRI investigation into the relational complexity of higher-order intentionality. Conscious Cognitive 17, 438–450.
Agnew, Z.K., Bhakoo, K.K., Puri, B.K., 2007. The humanmirror system: amotor resonancetheory of mind-reading. Brain Res. Rev. 54, 286–293.
Allison, T., Puce, A., McCarthy, G., 2000. Social perception from visual cues: role of theSTS region. Trends Cogn. Sci. 4, 267–278.
Amodio, D.M., Frith, C.D., 2006. Meeting of minds: the medial frontal cortex and socialcognition. Nat. Rev. 7, 268–277.
Barraclough, N.E., Xiao, D., Baker, C.I., Oram, M.W., Perrett, D.I., 2005. Integration ofvisual and auditory information by superior temporal sulcus neurons responsive tothe sight of actions. J. Cogn. Neurosci. 17, 377–391.
Blakemore, S.J., Winston, J., Frith, U., 2004. Social cognitive neuroscience: where are weheading? Trends Cogn. Sci. 8, 216–222.
Brass, M., Zysset, S., von Cramon, D.Y., 2001. The inhibition of imitative responsetendencies. NeuroImage 14, 1416–1423.
Brass, M., Derrfuss, J., von Cramon, D.Y., 2005. The inhibition of imitative and over-learned responses: a functional double dissociation. Neuropsychologia 43, 89–98.
⁎Brass,M., Schmitt, R.M., Spengler, S., Gergely, G., 2007. Investigatingactionunderstanding:inferential processes versus action simulation. Curr. Biol. 17, 2117–2121.
⁎Buccino, G., Baumgaertner, A., Colle, L., Buechel, C., Rizzolatti, G., Binkofski, F., 2007. Theneural basis for understanding non-intended actions. Neuroimage 36, T119–T127.
Calvo-Merino, B., Glaser, D.E., Grezes, J., Passingham, R.E., Haggard, P., 2005. Actionobservation and acquired motor skills: an FMRI study with expert dancers. Cereb.Cortex 15, 1243–1249.
Calvo-Merino, B., Grezes, J., Glaser, D.E., Passingham, R.E., Haggard, P., 2006. Seeing ordoing? Influence of visual and motor familiarity in action observation. Curr. Biol. 16,1905–1910.
Cavanna, A.E., Trimble, M.R., 2006. The precuneus: a review of its functional anatomyand behavioural correlates. Brain 129, 564–583.
⁎Ciaramidaro, A., Adenzato, M., Enrici, I., Erk, S., Pia, L., Bara, B.G., Walter, H., 2007. Theintentional network: how the brain reads varieties of intentions. Neuropsychologia45, 3105–3113.
Collins, D.L., Neelin, P., Peters, T.M., Evans, A.C., 1994. Automatic 3D intersubjectregistration of MR volumetric data in standardized Talairach space. J. Comput.Assist. Tomogr. 18, 192–205.
Corbetta, M., Kincade, J.M., Ollinger, J.M., McAvoy, M.P., Shulman, G.L., 2000. Voluntaryorienting is dissociated from target detection in human posterior parietal cortex.Nature Neuroscience 3, 292–297.
⁎Corbetta, M., Shulman, G.L., 2002. Control of goal-directed and stimulus-drivenattention in the brain. Nat. Rev. Neurosci. 3, 201–215.
⁎Corbetta, M., Kincade, J.M., Shulman, G.L., 2002. Neural systems for visual orienting andtheir relationships to spatial working memory. J. Cogn. Neurosci. 14, 508–523.
Cross, E.S., Hamilton, A.F., Grafton, S.T., 2006. Building a motor simulation de novo:observation of dance by dancers. NeuroImage 31, 1257–1267.
Decety, J., Chaminade, T., 2003. Neural correlates of feeling sympathy. Neuropsychologia41, 127–138.
Decety, J., Lamm, C., 2007. The role of the right temporoparietal junction in socialinteraction: how low-level computational processes contribute to meta-cognition.Neurosci. 13, 580–593.
⁎de Lange, F.P., Spronk, M., Willems, R.M., Toni, I., Bekkering, H., 2008. Complementarysystems for understanding action intentions. Curr. Biol. 18, 454–457.
⁎Dinstein, I., Hasson, U., Rubin, N., Heeger, D.J., 2007. Brain areas selective for bothobserved and executed movements. J. Neurophysiol. 98, 1415–1427.
Dinstein, I., Gardner, J.L., Jazayeri, M., Heeger, D.J., 2008. Executed and observedmovements have different distributed representations in human aIPS. J. Neurosci.28, 11231–11239.
Donner, T.H., Siegel, M., Oostenveld, R., Fries, P., Bauer, M., Engel, A.K., 2007. Populationactivity in the human dorsal pathway predicts the accuracy of visual motiondetection. J. Neurophysiol. 98, 345–359.
Driver, J., Davis, G., Ricciardelli, P., Kidd, P., Maxwell, E., Baron-Cohen, S., 1999. Gazeperception triggers reflexive visuospatial orienting. Vis. Cogn. 6, 509–540.
Emery, N.J., 2005. The evolution of social cognition. In: Easton, A., Emery, N.J. (Eds.),The Cognitive Neuroscience of Social Behavior. InPsychology Press, New York, NY,pp. 115–156.
Etzel, J.A., Gazzola, V., Keysers, C., 2008. Testing simulations theory with cross-modelmultivariate classification of fMRI data. Plos One 3, 1–6.
⁎Ferstl, E.C., von Cramon, D.Y., 2002. What does the frontomedian cortex contribute tolanguage processing: coherence or theory of mind? NeuroImage 17, 1599–1612.
Fogassi, L., Ferrari, P.F., Gesierich, B., Rozzi, S., Chersi, F., Rizzolatti, G., 2005. Parietal lobe:from action organization to intention understanding. Science 308, 662–667.
Freedman, D.J., Assad, J.A., 2006. Experience-dependent representation of visualcategories in parietal cortex. Nature 443, 85–88.
Frith, C.D., Frith, U., 1999. Interacting minds: a biological basis. Science 286, 1692–1695.⁎Galati, G., Committeri, G., Spitoni, G., Aprile, T., Di Russo, F., Pitzalis, S., Pizzamiglio, L.,
2008. A selective representation of the meaning of actions in the auditory mirrorsystem. NeuroImage 40, 1274–1286.
Gallagher, H.L., Frith, C.D., 2003. Functional imaging of ‘theory of mind’. Trends Cogn.Sci. 7, 77–83.
Gallese, V., Keysers, C., Rizzolatti, G., 2004. A unifying view of the basis of socialcognition. Trends Cogn. Sci. 8, 396–403.
⁎Gazzola, V., Aziz-Zadeh, L., Keysers, C., 2006. Empathy and the somatotopic auditorymirror system in humans. Curr. Biol. 16, 1824–1829.
⁎Gazzola, V., Worp, H., Mulder, T., Wicker, B., Rizzolatti, G., Keysers, C., 2007a. Aplasicsborn without hands mirror the goal of hand actions with their feet. Curr. Biol. 17,1235–1240.
⁎Gazzola, V., Rizzolatti, G., Wicker, B., Keysers, C., 2007b. The anthropomorphic brain:the mirror neuron system responds to human and robotic actions. Neuroimage 35,1674–1684.
George, N., Conty, L., 2008. Facing the gaze of others. Neurophysiologie Clinique/ClinicalNeurophysiology 38, 197–207.
⁎Gobbini, M.I., Koralek, A.C., Bryan, R.E., Montgomery, K.J., Haxby, J.V., 2007. Two takeson the social brain: a comparison of theory of mind tasks. J. Cogn. Neurosci. 19,1803–1814.
Gottlieb, J., 2007. From thought to action: the parietal cortex as a bridge betweenperception, action, and cognition. Neuron 53, 9–16.
⁎Greene, J.D., Nystrom, L.E., Engell, A.D., Darley, J.M., Cohen, J.D., 2004. The neural basesof cognitive conflict and control in moral judgment. Neuron 44, 389–400.
Ham, J., Vonk, R., 2003. Smart and easy: co-occurring activation of spontaneous traitinferences and spontaneous situational inferences. J. Exp. Soc. Psychol. 39, 434–447.
⁎Hamilton, A.C., Grafton, S., 2006. Goal representation in human anterior intraparietalsulcus. J. Neurosci. 26, 1133–1137.
⁎Hamilton, A.C., Grafton, S.T., 2008. Action outcomes are represented in human inferiorfronto-parietal cortex. Cereb. Cortex 18, 1160–1168.
582 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
Harris, L.T., Fiske, S.T., 2006. Dehumanizing the lowest of the low. Psychol. Sci. 17,847–853.
Heider, F., Simmel, M.,1944. An experimental study of apparent behavior. Am. J. Psychol.57, 243–259.
Henson, R., 2006. Forward inference using functional neuroimaging: dissociationsversus associations. Trends Cogn. Sci. 10, 64–67.
⁎Hooker, C.I., Paller, K.A., Gitelman, D.R., Parrish, T.B., Mesulam, M.M., Reber, P.J., 2003.Brain networks for analyzing eye gaze. Cogn. Brain Res. 17, 406–418.
Husain, M., Nachev, P., 2006. Space and the parietal cortex. Trends Cogn. Sci. 11, 30–36.Iacoboni, M., 2005. Neural mechanisms of imitation. Curr. Opin. Neurobiol. 15, 632–637.⁎Iacoboni, M., Woods, R.P., Brass, M., Bekkering, H., Mazziotta, J.C., Rizzolatti, G., 1999.
Cortical mechanisms of human imitation. Science 286, 2526–2527.⁎Iacoboni, M., Molnar-Szakacs, I., Gallese, V., Buccino, G., Mazziotta, J.C., Rizzolatti, G.,
2005. Grasping the intentions of others with one's ownmirror neuron system. PLoSBiology 3, 529–535.
Jacob, P., Jeannerod, M., 2005. The motor theory of social cognition: a critique. TrendsCogn. Sci. 9, 21–25.
Joly, J.F., Stapel, D.A., Lindenberg, S.M., 2008. Silence and table manners: whenenvironments activate norms. Pers. Soc. Psychol. Bull. 34, 1047–1056.
Keysers, C., Gazzola, V., 2006. Towards a unifying neural theory of social cognition. Prog.Brain Res. 156, 379–401.
Keysers, C., Perrett, D.I., 2004. Demystifying social cognition: a Hebbian perspective.Trends Cogn. Sci. 8, 501–507.
Keysers, C., Gazzola, V., 2007. Integrating simulation and theory of mind: from self tosocial cognition. Trends Cogn. Sci. 11, 194–196.
Langton, S.R., Watt, R.J., Bruce, I.I., 2000. Do the eyes have it? Cues to the direction ofsocial attention. Trends Cogn. Sci. 4, 50–59.
Ma, N., Baetens, K., Van Overwalle, F., 2009. Beware of explicit instructions: onlyspontaneous trait inferences activate the core mentalizing system. Manuscript inpreparation.
⁎Mar, R.A., Kelley, W.M., Heatherton, T.F., and Macrae, C.N., 2007. Detecting agency fromthe biological motion of veridical vs animated agents. Soc. Cogn. Affect. Neurosci. 2,199–205.
Martinez-Trujillo, J.C., Cheyne, D., Gaetz, W., Simine, E., Tsotsos, J.K., 2007. Activation ofarea MT/V5 and the right inferior parietal cortex during the discrimination oftransient direction changes in translational motion. Cereb. Cortex 17, 1733–1739.
⁎Materna, S., Dicke, P.W., Their, P., 2008. The posterior superior temporal sulcus isinvolved in social communication not specific for the eyes. Neuropsychologia 46,2759–2765.
Matsumoto, K., Tanaka, K., 2004. The role of the medial prefrontal cortex in achievinggoals. Curr. Opin. Neurobiol. 14, 178–185.
Mitchell, J.P., 2006. Mentalizing and Marr: an information processing approach to thestudy of social cognition. Brain Res. 1079, 66–75.
⁎Mitchell, J.P., 2008. Activity in right temporo-parietal junction is not selective fortheory of mind. Cereb. Cortex 18, 262–271.
Mitchell, J.P., Ames, D.L., Jenkins, A.C., Banaji, M.R., 2009. Neural correlates of stereotypeapplication. Journal of Cognitive Neuroscience 21, 594–604.
Morin, O., Grèzes, J., 2008. What is “mirror” in the premotor cortex? A review.Neurophysiology Clinique 38, 189–195.
Nishitani, N., Hari, R., 2002. Viewing lip forms: cortical dynamics. Neuron 36, 1211–1220.⁎Ohnishi, T., Moriguchi, Y., Matsuda, H., Mori, T., Hirakata, M., Imabayashi, E., Hirao, K.,
Nemoto, K., Kaga, M., Inagaki, M., Yamada, M., Uno, A., 2004. The neural network forthe mirror system and mentalizing in normally developed children: an fMRI study.NeuroReport 15, 1483–1487.
⁎Pelphrey, K.A., Viola, R.J., McCarthy, G., 2004b. When strangers pass. Psychol. Sci. 15,598–603.
⁎Pelphrey, K.A., Morris, J.P., Michelich, C.R., Allison, T., McCarthy, G., 2005. Functionalanatomy of biological motion perception in posterior temporal cortex: an fMRIstudy of eye, mouth and hand movements. Cereb. Cortex 15, 1866–1876.
⁎Pierno, A.C., Becchio, C., Wall, M.B., Smith, A.T., Turella, L., Castiello, U., 2006b. Whengaze turns into grasp. J. Cogn. Neurosci. 18, 2130–2137.
⁎Pierno, A.C., Becchio, C., Turella, L., Tubaldi, F., Castiello, U., 2008. Observing socialinteractions: the effect of gaze. Soc. Neurosci. 3, 51–59.
Pulvermüller, F., 2005. Brain mechanisms linking language and action. Nat. Rev.Neurosci. 6, 576–582.
Redcay, E., 2008. The superior temporal sulcus performs a common function for socialand speech perception: implications for the emergence of autism. Neurosci.Biobehav. Rev. 32, 123–142.
Rizzolatti, G., Fogassi, L., Gallese, V., 2001. Neurophysiological mechanisms underlyingthe understanding and imitation of action. Nat. Rev. Neurosci. 2, 661–670.
Saxe, R., 2005. Against simulation: the argument from error. Trends Cogn. Sci. 9,174–179.
Saxe, R., 2006. Uniquely human social cognition. Curr. Opin. Neurobiol. 16, 235–239.⁎Saxe, R., Wexler, A., 2005. Making sense of anothermind: the role of the right temporo-
parietal junction. Neuropsychologia 43, 1391–1399.⁎Saxe, R., Powell, L.J., 2006. It's the thought that counts: specific brain regions for one
component of theory of mind. Psychol. Sci. 17, 692–699.Saxe, R., Carey, S., Kanwisher, N., 2004a. Understanding other minds: linking develop-
mental psychology and functional neuroimaging. Annu. Rev. Psychol. 55, 87–124.⁎Saxe, R., Schulz, L.E., Jiang, Y.V., 2006. Reading minds versus following rules:
dissociating theory of mind and executive control in the brain. Soc. Neurosci. 1,284–298.
Shulman, G.L., Ollinger, J.M., Linenweber, M., Petersen, S.E., Corbetta, M., 2001. Multipleneural correlates of detection in the human brain. PNAS 98, 313–318.
Speer, N., Zacks, J., Reynolds, J., 2007. Human brain activity time-locked to narrativeevent boundaries. Psychol. Sci. 18, 449–455.
⁎Spiers, H.J., Maguire, E.A., 2006. Spontaneous mentalizing during an interactive realworld task: an fMRI study. Neuropsychologia 44, 1674–1682.
Talairach, J., Tournoux, P., 1988. Co-planar Stereotaxic Atlas of the Human Brain. Thieme,Stuttgart.
Tunik, E., Rice, N.J., Hamilton, A., Grafton, S.T., 2007. Beyond grasping: representation ofaction in human anterior intraparietal sulcus. NeuroImage 36, T77–86.
Turella, L., Pierno, A.C., Tubaldi, F., Castiello, U., 2009. Mirror neurons in humans:consisting or confounding evidence. Brain and Language 108, 10–21.
Uddin, L.Q., Iacoboni, M., Lange, C., Keenan, J.P., 2007. The self and social cognition: therole of cortical midline structures andmirror neurons. Trends Cogn. Sci. 11, 153–157.
Uleman, J.S., Blader, S.L., Todorov, A., 2005. Implicit impressions. In: Hassin, R.R.,Uleman, J.S., Bargh, J.A. (Eds.), The New Unconscious. InOxford University Press,New York, pp. 362–392.
Van der Cruyssen, L., Van Duynslaeger, M., Cortoos, A., Van Overwalle, F., 2009. ERP timecourse and brain areas of spontaneous and intentional goal inferences. Soc.Neurosci. 4, 165–184.
Van Duynslaeger, M., Van Overwalle, F., Verstraeten, E., 2007. Electrophysiological timecourse and brain areas of spontaneous and intentional trait inferences. Soc. Cogn.Affect. Neurosci. 2, 174–188.
Van Overwalle, F., 2009. Social cognition and the brain: a meta-analysis. Hum. BrainMapp. 30, 829–858.
⁎Völlm, B.A., Taylor, A.N.W., Richardson, P., Corcoran, R., Stirling, J., McKie, S., Deakin,J.F.W., Elliott, R., 2006. Neuronal correlates of theory of mind and empathy: afunctional magnetic resonance imaging study in a nonverbal task. NeuroImage 29,90–98.
Wimmer, H., Perner, J.,1983. Beliefs about beliefs: representation and constraining functionofwrongbeliefs inyoungchildren'sunderstandingof deception.Cognition13,103–128.
Further reading
References in Table 1⁎Aichhorn, M., Perner, J., Kronbichler, M., Staffen, W., Ladurner, G., 2006. Do visual
perspective tasks need theory of mind? NeuroImage 30, 1059–1068.⁎Astafiev, S.V., Shulman, G.L., Corbetta, M., 2006. Visuospatial reorienting signals in the
human temporo-parietal junction are independent of response selection. Eur. J.Neurosci. 23, 591–596.
⁎Aziz-Zadeh, L., Koski, L., Zaidel, E., Mazziotta, J., Iacoboni, M., 2006. Lateralization of thehuman mirror system. J. Neurosci. 26, 2964–2970.
⁎Balslev, D., Nielsen, F.A., Paulson, O.B., Law, I., 2005. Right temporoparietal cortexactivation during visuo-proprioceptive conflict. Cereb. Cortex 15, 166–169.
⁎Balslev, D., Nielsen, F.A., Lund, T.E., Law, I., Paulson, O.B., 2006. Similar brain networks fordetecting visuo-motor and visuo-proprioceptive synchrony. NeuroImage 31,308–312.
⁎Baumgaertner, A., Buccino, G., Lange, R., Mcnamara, A., Binkofski, F., 2007. Polymodalconceptual processing of human biological actions in left inferior frontal lobe. Eur. J.Neurosci. 25, 881–889.
⁎Beauchamp, M.S., Lee, K.E., Haxby, J.V., Martin, A., 2002. Parallel visual motionprocessing streams for manipulable objects and human movements. Neuron 34,149–159.
⁎Beauchamp, M.S., Lee, K.E., Haxby, J.V., Martin, A., 2003. fMRI responses to video andpoint-light displays of moving humans and manipulable objects. J. Cogn. Neurosci.15, 991–1001.
⁎Berthoz, S., Armony, J.L., Blain, R.J.R., Dolan, R.J., 2002. An fMRI study of intentional andunintentional (embarrassing) violations of social norms. Brain 125, 1696–1708.
⁎Bidet-Caulet, A., Voisin, J., Bertrand, O., Fonlupt, P., 2005. Listening to a walking humanactivates the temporal biological motion area. NeuroImage 28, 132–139.
⁎Binkofski, F., Dohle, C., Posse, S., Stephan, K.M., Hefter, H., Seitz, R.J., Freund, H.J., 1998.Human anterior intraparietal area subserves prehension: a combined lesion andfunctional MRI activation study. Neurology 50, 1253–1259.
⁎Binkofski, F., Buccino, G., Posse, S., Seitz, R.J., Rizzolatti, G., Freund, H., 1999a. A fronto-parietal circuit for object manipulation in man: evidence from an fMRI-study.European Journal of Neuroscience 11, 3276–3286.
⁎Binkofski, F., Buccino, G., Stephan, K.M., Rizzolatti, G., Seitz, R.J., Freund, H.J., 1999b. Aparieto-premotor network for object manipulation: evidence from neuroimaging.Exp. Brain Res. 128, 210–213.
⁎Blakemore, S.J., Boyer, P., Pachot-Clouard, M., Meltzoff, A., Segebarth, C., Decety, J., 2003.The detection of contingency and animacy from simple animations in the humanbrain. Cereb. Cortex 8, 837–844.
⁎Blakemore, J.S., denOuden,H., Choudhury, S., Frith,C., 2007. Adolescent developmentof theneural circuitry for thinking about intentions. Soc. Cogn. Affect. Neurosci. 2, 130–139.
⁎Borg, J.S., Hynes, C., Van Horn, J., Grafton, S., Sinnott-Armstrong, W., 2006.Consequences, action, and intention as factors in moral judgments: an fMRIinvestigation. J. Cogn. Neurosci. 5, 803–817.
⁎Bristow, D., Rees, G., Frith, C.D., 2007. Social interaction modifies neural response togaze shifts. Soc. Cogn. Affect. Neurosci. 2, 52–61.
⁎Buccino, G., Binkofski, F., Fink, G.R., Fadiga, L., Fogassi, L., Gallese, V., Seitz, R.J., Zilles, K.,Rizzolatti, G., Freund, H.J., 2001. Action observation activates premotor and parietalareas in a somatotopic manner: an fMRI study. Eur. J. Neurosci. 13, 400–404.
⁎Buccino, G., Lui, F., Canessa, N., Patteri, I., Lagravinese, G., Benuzzi, F., Porro, C.A.,Rizzolatti, G., 2004a. Neural circuits involved in the recognition of actionsperformed by nonconspecifics: an FMRI study. J. Cogn. Neurosci. 16, 114–126.
⁎Buccino, G., Vogt, S., Ritzl, A., Fink, G.R., Zilles, K., Freund, H.J., et al., 2004b. Neuralcircuits underlying imitation learning of hand actions: an event related fMRI study.Neuron 42, 323–334.
583F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
⁎Calvert, G.A., Campbell, R., 2003. Reading speech from still and moving faces: theneural substrates of visible speech. J. Cogn. Neurosci. 15, 57–70.
⁎Carr, L., Iacoboni, M., Dubeau, M.C., Mazziotta, J.C., Lenzi, G.L., 2003. Neural mechanismsof empathy in humans: a relay from neural systems for imitation to limbic areas.Proc. Natl. Acad. Sci. 100, 5497–5502.
⁎Carter, E.J., Pelphrey, K.A., 2006. School-aged children exhibit domain-specificresponses to biological motion. Social Neuroscience 1, 396–411.
⁎Chao, L.L., Martin, A., 2000. Representation of manipulable man-made objects in thedorsal stream. NeuroImage 12, 478–484.
⁎Cheng, Y., Meltzoff, A.N., Decety, J., 2007. Motivation modulates the activity of thehuman mirror-system. Cereb. Cortex 17, 1979–1986.
⁎Choi, S.H., Na, D.L., Kang, E., Lee, K.M., Lee, S.W., Na, D.G., 2001. Functional magneticresonance imaging during pantomiming tool-use gestures. Experimental BrainResearch 139, 311–317.
⁎Costantini, M., Galati, G., Ferretti, A., Caulo, M., Tartaro, A., Romani, G.L., et al., 2005.Neural systems underlying observation of humanly impossible movements: anfMRI study. Cereb. Cortex 15, 1761–1767.
⁎Culham, J.C., Danckert, S.L., DeSouza, J.F., Gati, J.S., Menon, R.S., Goodale, M.A., 2003.Visually guided grasping produces fMRI activation in dorsal but not ventral streambrain areas. Experimental Brain Research 153, 180–189.
⁎Cunnington, R., Windischberger, C., Robinson, S., Moser, E., 2006. The selection ofintended actions and the observation of others' actions: a time-resolved fMRI study.NeuroImage 29, 1294–1302.
⁎David, N., Bewernick, B.H., Cohen, M.X., Newen, A., Lux, S., Fink, G.R., Shah, N.J., Vogeley,K., 2006. Neural representations of self versus other: visual-spatial perspectivetaking. J. Cogn. Neurosci. 6, 898–910.
⁎David, N., Aumann, C., Santos, N.S., Bewernick, B.H., Eickhoff, S.B., Newen, A., Shah, N.J.,Fink, G.R., Vogeley, K., 2008. Differential involvement of the posterior temporal cortexin mentalizing but not perspective taking. Soc. Cogn. Affect. Neurosci. 3, 279–289.
⁎Decety, J.,Michalska,K.J., Akitsuki, Y., 2008.Whocaused thepain?An fMRI investigationofempathy and intentionality in children. Neuropsychologia 46, 2607–2614.
⁎den Ouden, H.E.M., Frith, U., Frith, C., Blakemore, S.J., 2005. Thinking about intentions.NeuroImage 28, 787–796.
⁎Downar, J., Crawley, A.P., Mikulis, D.J., Davis, K.D., 2000. A multimodal corticalnetwork for the detection of changes in the sensory environment. Nat. Neurosci. 3,277–283.
⁎Downar, J., Crawley, A.P., Mikulis, D.J., Davis, K.D., 2001. The effect of task relevance onthe cortical response to changes in visual and auditory stimuli: an event-relatedfMRI study. NeuroImage 14, 1256–1267.
⁎Downar, J., Crawley, A.P., Mikulis, D.J., Davis, K.D., 2002. A cortical network sensitive tostimulus salience in a neutral behavioral context across multiple sensorymodalities. J. Neurophysiol. 87, 615–620.
⁎Dubeau, M.C., Iacoboni, M., Koski, L.M., Markovac, J., Mazziotta, J.C., 2001. Topographyfor body parts motion in the STS region. Social Neuroscience Abstracts 27Unpublished Poster.
⁎Ehrsson, H.H., Fagergren, E., Forssberg, H., 2001. Differential frontoparietal activationdepending on force used in a precision grip task: an fMRI study. Journal ofNeurophysiology 85, 2613–2623.
⁎Engel, A., Burke, M., Fiehler, K., Bien, S., Rösler, F., 2008. What activates the humanmirror system during observation of artificial movements: bottom-up visualfeatures or top-down intentions? Neuropsychologia 46, 2033–2042.
⁎Farrer, C., Frith, C.D., 2002. Experiencing oneself vs. another person as being the cause ofan action: the neural correlates of the experience of agency. NeuroImage 15, 596–603.
⁎Farrer, C., Frey, S.H., Van Horn, J.D., Tunik, E., Turk, D., Inati, S., Grafton, S.T., 2008. Theangular gyrus computes action awareness representations. Cereb. Cortex 18, 254–261.
⁎Fiddick, L., Spampinato, M.V., Grafman, J., 2005. Social contracts and precautionsactivate different neurological systems: an fMRI investigation of deontic reasoning.NeuroImage 28, 778–786.
⁎Filimon, F., Nelson, J.D., Hagler, D.J., Sereno, M.I., 2007. Human cortical representationsfor reaching: mirror neurons for execution, observation, and imagery. Neuroimage37, 1315–1328.
⁎Fonlupt, P., 2003. Perception and judgement of physical causality involve differentbrain structures. Cogn. Brain Res. 17, 248–254.
⁎Frey, S.H., Vinton, D., Norlund, R., Grafton, S.T., 2005. Cortical topography of humananterior intraparietal cortex active during visually-guided grasping. Cognitive BrainResearch 23, 397–405.
⁎Fridman, E.A., Immisch, I., Hanakawa, T., Bohlhalter, S., Waldvogel, D., Kansaku, K.,Wheaton, L., Wu, T., Hallett, M., 2006. The role of the dorsal stream for gestureproduction. NeuroImage 29, 417–428.
⁎Gallagher, H.L., Happé, F., Brunswick, N., Fletcher, P.C., Frith, U., Frith, C.D., 2000.Reading the mind in cartoons and stories: an fMRI study of theory of mind in verbaland nonverbal tasks. Neuropsychologia 38, 1–21.
⁎German, T.P., Niehaus, J.L., Meghan, P., Roarty, M.P., Giesbrecht, B., Miller, M.B., 2004.Neural correlates of detecting pretense: automatic engagement of the intentionalstance under covert conditions. J. Neurosci. 16, 1805–1817.
⁎Giessing, C., Thiel, C.M., Stephan, K.E., Rösler, K., Fink, G.R., 2004. Visuospatial attention:how to measure effects of infrequent, unattended events in a blocked stimulusdesign. NeuroImage 23, 1370–1381.
⁎Giessing, C., Thiel, C.M., Roesler, F., Fink, G., 2006. The modulatory effects of nicotine onparietal cortex activity in a cued target detection task depend on cue reliability.Neuroscience 137, 853–864.
⁎Greene, J., Sommerville, R.B., Nystrom, L.E., Darley, J.M., Cohen, J.D., 2001. An fMRIinvestigation of emotional engagement inmoral judgment. Science 293, 2105–2108.
⁎Grèzes, J., Decety, J., 2001. Functional anatomy of execution, mental simulation,observation, and verb generation of actions: a meta-analysis. Hum. Brain Mapp. 12,1–19.
⁎Grèzes, J., Armony, J.L., Rowe, J., Passingham, R.E., 2003. Activations related to ‘mirror’ and‘canonical’ neurons in the human brain: an fMRI study. NeuroImage 18, 928–937.
⁎Grèzes, J., Frith, C., Passingham, R.E., 2004a. Brain mechanisms for inferring deceit inthe actions of others. J. Neurosci. 24, 5500–5505.
⁎Grèzes, J., Frith, C., Passingham, R.E., 2004b. Inferring false beliefs from the actions ofoneself and others: an fMRI study. NeuroImage 21, 744–750.
⁎Grosbras, M.H., Paus, T., 2006. Brain networks involved in viewing angry hands andfaces. Cereb. Cortex 16, 1087–1096.
⁎Grossman, E.D., Blake, R., 2002. Brain areas active during visual perception ofbiological motion. Neuron 35, 1167–1175.
⁎Hamzei, F., Rijntjes, M., Dettmers, C., Glauche, V., Weiller, C., Buchel, C., 2003. Thehuman action recognition system and its relationship to Broca's area: an fMRIstudy. NeuroImage 19, 637–644.
⁎Hauk, O., Johnsrude, I., Pulvermüller, F., 2004. Somatotopic representation of actionwords in human motor and premotor cortex. Neuron 41, 301–307.
⁎Heekeren, H.R., Wartenburger, I., Schmidt, H., Schwintowski, H.P., Villringer, A., 2003.An fMRI study of simple ethical decision making. NeuroReport 14, 1215–1219.
⁎Heekeren, H.R., Wartenburger, I., Schmidt, H., Prehn, K., Schwintowski, H.P., Villringer,A., 2005. Influence of bodily harm on neural correlates of semantic and moraldecision-making. NeuroImage 24, 887–897.
⁎Hoffman, E.A., Haxby, J.V., 2000. Distinct representations of eye gaze and identityin the distributed human neural system for face perception. Nat. Neurosci. 3,80–84.
⁎Hynes, C.A., Baird, A.A., Grafton, S.T., 2006. Differential role of the orbitofrontal lobe inemotional versus cognitive perspective-taking. Neuropsychologia 44, 374–383.
⁎Indovina, I., Macaluso, E., 2006. Dissociation of stimulus relevance and saliency factorsduring shifts of visuospatial attention. Cereb. Cortex 17, 1701–1711.
⁎Iseki, K., Hanakawa, T., Shinozaki, J., Nankaku, M., Fukuyama, H., 2008. Neuralmechanisms involved in mental imagery and observation of gait. NeuroImage 41,1021–1031.
⁎Jackson, P.L., Meltzoff, A.N., Decety, J., 2006. Neural circuits involved in imitation andperspective-taking. NeuroImage 31, 429–439.
⁎Jancke, L., Kleinschmidt, A., Mirzazade, S., Shah, N.J., Freund, H.J., 2001. The role of theinferior parietal cortex in linking the tactile perception and manual construction ofobject shapes. Cerebral Cortex 11, 114–121.
⁎Johnson-Frey, S.H., Newman-Nordlund, R., Grafton, S.T., 2005. A distributed lefthemisphere network active during planning of everyday tool. Cerebral Cortex 6,681–695.
⁎Johnson-Frey, S.H., Maloof, F.R., Newman-Orlund, R., Farrer, C., Inati, S., Grafton, S.T.,2003. Actions or hand-object interactions? Human inferior frontal cortex andaction observation. Neuron 39, 1053–1058.
⁎Jonas, M., Siebner, H.R., Biermann-Ruben, K., Kessler, K., Bäumer, T., Büchel, C., et al.,2007. Do simple intransitive finger movements consistently activate frontoparietalmirror areas in humans? NeuroImage 36, T44–T53.
⁎Kable, J.W., Chatterjee, A., 2006. Specificity of action representations in the lateraloccipitotemporal cortex. J. Cogn. Neurosci. 18, 1498–1517.
⁎Kincade, M., Abrams, R.A., Astafiev, S.V., Shulman, G.L., Corbetta, M., 2005. An event-related functional magnetic resonance imaging study of voluntary and stimulus-driven orienting of attention. J. Neurosci. 25, 4593–4604.
⁎Kobayashi, C., Glover, G.H., Temple, E., 2007. Children's and adults' neural bases ofverbal and nonverbal ‘theory of mind’. Neuropsychologia 45, 1522–1532.
⁎Konrad, K., Neufang, S., Thiel, C.M., Specht, K., Hanisch, C., Fan, J., et al., 2005.Development of attentional networks: an fMRI study with children and adults.NeuroImage 28, 429–439.
⁎Koski, L., Iacoboni, M., Dubeau, M.C., Woods, R.P., Mazziotta, J.C., 2003. Modulation ofcortical activity during different imitative behaviors. J. Neurophysiol. 89, 460–471.
⁎Lepsien, J., Pollmann, S., 2006. Covert reorienting and inhibition of return: an event-related fMRI study. J. Cogn. Neurosci. 14, 127–144.
⁎Leslie, A.M., Friedman, O., German, T.P., 2004. Core mechanisms in ‘theory of mind.Trends Cogn. Sci. 8, 528–533.
⁎Macaluso, E., Frith, C.D., Driver, J., 2002. Supramodal effects of covert spatial orientingtriggered by visual or tactile events. J. Cogn. Neurosci. 143, 389–401.
⁎Makuuchi, M., 2005. Is Broca's area crucial for imitation? Cerebral Cortex 15, 563–570.⁎Manthey, S., Schubotz, R., von Cramon, D.Y., 2003. Premotor cortex in observing
erroneous action: an fMRI study. Cogn. Brain Res. 15, 296–307.⁎Martin, A., Weisberg, J., 2003. Neural foundations for understanding social and
mechanical concepts. Cogn. Neuropsychol. 20, 575–587.⁎Moll, J., Eslinger, P.J., De Oliveira-Souza, R., 2001. Frontopolar and anterior temporal
cortex activation in a moral judgment task. Arq. Neuropsiquiatr. 59, 657–664.⁎Moll, J., de Oliveira-Souza, R., Bramati, I.E., Grafman, J., 2002a. Functional networks in
emotional moral and nonmoral social judgments. NeuroImage 16, 696–703.⁎Moll, J., Oliveira-Souza, R., Eslinger, P.J., Bramati, I.E., Mourao-Miranda, J., Andreiuolo,
P.A., Pessoa, L., 2002b. The neural correlates of moral sensitivity: a functionalmagnetic resonance imaging investigation of basic moral emotions. J. Neurosci. 22,2730–2738.
⁎Molnar-Szakacs, I., Iacoboni, M., Koski, L., Mazziotta, J.C., 2005. Functional segregationwithin pars opercularis of the inferior frontal gyrus: evidence from fMRI studies ofimitation and action observation. Cereb. Cortex 15, 986–994.
⁎Molnar-Szakacs, I., Kaplan, J., Greenfield, P.M., Iacoboni, M., 2006. Observing complexaction sequences: the role of the fronto-parietal mirror neuron system. NeuroImage33, 923–935.
⁎Moriguchi, Y., Ohnishi, T., Lane, R.D., Maeda, M., Mori, T., Nemoto, K., et al., 2006.Impaired of self-awareness and theory of mind: an fMRI study mentalizing inalexithymia. NeuroImage 32, 1472–1482.
⁎Morris, J.P., Pelphrey, K.A., McCarthy, G., 2005. Regional brain activation evoked whenapproaching a virtual human on a virtual walk. J. Cogn. Neurosci. 17, 1744–1752.
584 F. Van Overwalle, K. Baetens / NeuroImage 48 (2009) 564–584
⁎Mosconi, M.W., Peter, B., Mack, P.B., McCarthy, G., Pelphrey, K.A., 2005. Taking an“intentional stance” on eye-gaze shifts: a functional neuroimaging study of socialperception in children. NeuroImage 27, 247–252.
⁎Mühlau, M., Hermsdorfer, J., Goldenberg, G.,Wohlschlager, A.M., Castrop, F., Stahl, et al.,2005. Left inferior parietal dominance in gesture imitation: an fMRI study.Neuropsychologia 43, 1086–1098.
⁎Newman-Norlund, R.D., Bosga, J., Meulenbroek, R.G., Bekkering, H., 2008. Anatomicalsubstrates of cooperative joint-action in a continuous motor task: virtual lifting andbalancing. NeuroImage 41, 169–177.
⁎Noppeney, U., Josephs, O., Kiebel, S., Friston, K.J., Price, C.J., 2005. Action selectivity inparietal and temporal cortex. Cogn. Brain Res. 25, 641–649.
⁎Peelen, M.V., Wiggett, A.J., Downing, P.E., 2006. Patterns of fMRI activity dissociateoverlapping functional brain areas that respond to biological motion. Neuron 49,815–822.
⁎Pelphrey, K.A., Morris, J.P., McCarthy, G., 2004a. Grasping the intentions of others: theperceived intentionality of an action influences activity in the superior temporalsulcus during social perception. J. Cogn. Neurosci. 16, 1706–1716.
⁎Perner, J., Aichhorn, M., Kronbichler, M., Staffen, W., Ladurner, G., 2006. Thinking ofmental and other representations: the roles of left and right temporo-parietaljunction. Soc. Neurosci. 1, 245–258.
⁎Peuskens, H., Vanrie, J., Verfaillie, K., Orban, G.A., 2005. Specificity of regions processingbiological motion. Eur. J. Neurosci. 21, 2864–2875.
⁎Pierno, A.C., Becchio, C., Wall, M.B., Smith, A.T., Castiello, U., 2006a. Transfer ofinterfered motor patterns to self from others. Eur. J. Neurosci. 23, 1949–1955.
⁎Prehn, K.,Wartenburger, I., Mériau, K., Scheibe, C., Goodenough, O.R., Villringer, A., et al.,2008. Individual differences in moral judgment competence influence neural corre-lates of socio-normative judgments. Soc. Cogn. Affect. Neurosci. 3, 33–46.
⁎Puce, A., Allison, T., Bentin, S., Gore, J.C., McCarthy, G., 1998. Temporal cortex activationin humans viewing eye and mouth movements. J. Neurosci. 18, 2188–2199.
⁎Ramnani, N., Miall, R.C., 2004. A system in the human brain for predicting the actions ofothers. Nat. Neurosci. 7, 85–90.
⁎Robertson, D., Snarey, J., Ousley, O., Keith Harenski, K., Bowmand, F.D., Gilkey, R., Kilts,C., 2007. The neural processing of moral sensitivity to issues of justice and care.Neuropsychologia 45, 755–766.
⁎Sakreida, K., Schubotz, R.I., Wolfensteller, U., Cramon, D.Y., 2005. Motion classdependency in observer' motor areas revealed by functional magnetic resonanceimaging. J. Neurosci. 25, 1335–1342.
⁎Santi, A., Servos, P., Vatikiotis-Bateson, E., Kuratate, T., Munhall, K., 2003. Perceivingbiological motion: dissociating visible speech from walking. J. Cogn. Neurosci. 15,800–809.
⁎Sato,W., Kochiyama, T., Uono, S., Yoshikawa, S., 2008. Time course of superior temporalsulcus activity in response to eye gaze: a combined fMRI and MEG study. Social,Cognitive and Affective Neuroscience 3, 224–232.
⁎Saxe, R., Kanwisher, N., 2003. People thinking about people—the role of the temporo-parietal junction in theory of mind. NeuroImage 19, 1835–1842.
⁎Saxe, R., Xiao, D.K., Kovacsc, G., Perrett, D.I., Kanwisher, N., 2004b. A region of rightposterior superior temporal sulcus responds to observed intentional actions.Neuropsychologia 42, 1435–1446.
⁎Saygin, A.P., Wilson, S.M., Hagler, D.J., Bates, E., Sereno, M., 2004. Pointlight bio-logical motion perception activates human premotor cortex. J. Neurosci. 24,6181–6188.
⁎Schnell, K., Heekeren, K., Schnitker, R., Daumann, J., Weber, J., Heszelmann, V., et al.,2007. An fMRI approach to particularize the frontoparietal network for visuomotoraction monitoring: detection of incongruence between test subjects’ actions andresulting perceptions. NeuroImage 34, 332–341.
⁎Schilbach, L., Wohlschlaeger, A.M., Kraemer, N.C., Newen, A., Shah, N.J., Fink, G.R.,Vogeley, K., 2006. Being with virtual others: neural correlates of social interaction.Neuropsychologia 44, 718–730.
⁎Schubotz, R.I., von Cramon, D.Y., 2004. Sequences of abstract nonbiological stimulishare ventral premotor cortex with action observation and imagery. J. Neurosci. 24,5467–5474.
⁎Schultz, J., Imamizu, H., Kawato, M., Frith, C.D., 2004. Activation of the humansuperior temporal gyrus during observation of goal attribution by intentionalobjects. J. Cogn. Neurosci. 16, 1695–1705.
⁎Servos, P., Osu, R., Santi, A., Kawato, M., 2002. The neural substrates of biologicalmotion perception: an fMRI study. Cereb. Cortex 12, 772–782.
⁎Shane, M.S., Stevens, M., Harenski, C.L., Kiehl, K.A., 2008. Neural correlates of theprocessing of another's mistakes: a possible underpinning for social andobservational learning. Neuroimage 42, 450–459.
⁎Shikata, E., Hamzei, F., Glauche, V., Koch, M., Weiller, C., Binkofski, F., Buchel, C., 2003.Functional properties and interaction of the anterior and posterior intraparietalareas in humans. European Journal of Neuroscience 17, 1105–1110.
⁎Sommer, M., Döhnel, K., Sodian, B., Meinhardt, J., Thoermer, C., Hajak, G., 2007. Neuralcorrelates of true and false belief reasoning. NeuroImage 35, 1378–1384.
⁎Tavares, P., Lawrence, A.D., Barnard, P.J., 2008. Paying attention to social meaning: anFMRI study. Cereb. Cortex 18, 1876–1885.
⁎Tettamanti, M., Buccino, G., Saccuman, M.C., Gallese, V., Danna, M., Scifo, P., Fazio, F.,Rizzolatti, G., Cappa, S.F., Perani, D., 2005. Listening to action-related sentencesactivates fronto-parietal motor circuits. J. Cogn. Neurosci. 17, 273–281.
⁎Thiel, C.M., Zilles, K., Fink, G.R., 2004. Cerebral correlates of alerting, orienting andreorienting of visuospatial attention: an event-related fMRI study. NeuroImage 21,318–328.
⁎Todd, J.J., Fougnie, D., Marois, R., 2005. Visual short-term memory load suppressestemporo-parietal junction activity and induces inattentional blindness. Psychol. Sci.16, 965–972.
⁎Vaina, L.M., Solomon, J., Chowdhury, S., Sinha, P., Belliveau, J.W., 2001. Functionalneuroanatomy of biological motion perception in humans. Proc. Natl. Acad. Sci. 98,11656–11661.
⁎Valyear, K.F., Cavina-Pratesi, C., Stiglick, A.J., Culham, J.C., 2007. Does tool-related fMRIactivity within the intraparietal sulcus reflect the plan to grasp? NeuroImage 36,T94–T108.
⁎van der Gaag, C., Minderaa, R.B., Keysers, C., 2007. Facial expressions: what the mirrorneuron system can and cannot tell us. Soc. Neurosci. 2, 179–222.
⁎Villarreal, M., Fridman, E.A., Amengual, A., Falasco, G., Gerscovich, E.R., Ulloa, E.R.,Leiguarda, R.C., 2008. The neural substrate of gesture recognition. Neuropsychologia46, 2371–2382.
⁎Vogeley, K., Bussfeld, P., Newen, A., Herrmann, S., Happe, F., Falkai, P., et al., 2001. Mindreading: neural mechanism of theory of mind and self-perspective. NeuroImage 14,170–181.
⁎Vossel, S., Thiel, C.M., Fink, G.R., 2006. Cue validity modulates the neural correlates ofcovert endogenous orienting of attention in parietal and frontal cortex. NeuroImage32, 1257–1264.
⁎Wakusawa, K., Sugiura,M., Sassa, Y., Jeong, H., Horie, K., Sato, S., Yokoyama, H., Tsuchiya,S., Inuma, K., Kawashima, R., 2007. Comprehension of implicit meanings in socialsituations involving irony: a functional MRI study. NeuroImage 37, 1417–1426.
⁎Walter, H., Adenzato, M., Ciaramidaro, A., Enrici, I., Pia, L., Bara, B.G., 2004.Understanding intentions in social interaction: the role of the anterior para-cingulate cortex. J. Cogn. Neurosci. 16, 1854–1863.
⁎Wang, A.T., Lee, S.S., Sigman, M., Dapretto, M., 2006. Developmental changes in theneural basis of interpreting communicative intent. Social, Cognitive and AffectiveNeuroscience 1, 107–121.
⁎Wheaton, K.J., Thompson, J.C., Syngeniotis, A., Abbott, D.F., Puce, A., 2004. Viewing themotion of human body parts activates different regions of premotor, temporal, andparietal cortex. NeuroImage 22, 277–288.
⁎Williams, J.H.G., Waiter, G.D., Perra, O., Perrett, D.I., Whiten, A., 2005. An fMRI study ofjoint attention experience. NeuroImage 25, 133–140.
⁎Williams, J.H., Whiten, A., Waiter, G.D., Pechey, S., Perrett, D.I., 2007. Cortical andsubcortical mechanisms at the core of imitation. Soc. Neurosci. 2, 66–78.
⁎Young, L., Saxe, R., 2008. The neural basis of belief encoding and integration in moraljudgment. NeuroImage 40, 1912–1920.
⁎Young, L., Cushman, F., Hauser, M., Saxe, R., 2007. The neural basis of the interactionbetween theory of mind andmoral judgment. Proc. Natl. Acad. Sci. 104, 8235–8240.
