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Modeling and Imagery: Intro. Wilson & Knoblich, 2005. Conspecifics?. The case for motor involvement in perceiving conspecifics The idea that we use a part of motor cortex to interpret the movements of others of our species - PowerPoint PPT Presentation
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Modeling and Imagery: Intro
Wilson & Knoblich, 2005
Conspecifics? The case for motor involvement in
perceiving conspecifics•The idea that we use a part of motor cortex
to interpret the movements of others of our species
Starts with the notion that other people are special (perceptually), because they can be directly compared with ourselves (& they’re the only thing that can be)
Perceiving people Generates motor representation
•But no movement•So why have a movement plan without
movement? Purpose?
•It’s proposed here it’s for an emulator•This is something that in computer
hardware/software terms enables programs intended for one device to run on others
•Perhaps the motor plan enables us to predict other’s actions
Covert imitation of actions Chameleon effect
•Facial expression (cinema, the nodder)•Gestures & body sway (mothers/babies,
launderette, bar)•Tone of voice, pronunciation (Janet &
Corinne)•Ever watched a sport you play and
experienced that you are “playing” yourself?
Covert imitation of actions Automaticity of imitation
•Stimulus-response compatibility•Responses fastest when cue matches
response•Suggests motor programs for response are
best cued by watching the same or similar action•Which in turn suggests imitation is automatic
Covert imitation of actions Neonate imitation
•One-month olds•Mouth opening, tongue protrusion, facial
expression of emotion, blinking, vowel sounds, /m/ sound…
•“Slightly older”•Tongue protrusion to side, more consonants
Covert imitation of actions Frontal lobe damage
Loss of inhibition Automatic tendency to imitate
•(evidence for covert but inhibited imitation in the rest of us)
Covert imitation of actions Mirror Neurons
•Previous examples: overt imitation
•This example: covert imitation exists when overt behavior is absent
•These neurons (in premotor cortex of monkey) fire both when acting and when watching actionDiagram shows activity in both
premotor and parietal areas
Covert imitation of actions Mirror Neurons
•Previous examples: overt imitation•This example: covert imitation exists when
overt behavior is absent•These neurons (in premotor cortex of monkey)
fire both when acting and when watching action•Note: this is in monkeys, not humans, but the
idea is that perhaps we also have imitative circuitry in our brains
Covert imitation of actions Activation of motor
planning areas in humans• Observation of other’s body
movement (finger, hand, arm, mouth, foot) leads to activation of motor cortex•Only occurs for plausible
movements•Also occurs for complex
movements…more so for those who are expert in the activities
•Heard sounds promote activation of hand parts of motor cortex
Covert imitation of actions Activation of motor planning
areas in humans• Observation of other’s body
movement (finger, hand, arm, mouth, foot) leads to activation of motor cortex• Implies new mappings can be
learned•Mappings can be from
different stimuli (don’t have to be matched, e.g. hand for hand)
•Thus music can be “heard” as movement, provided you are familiar with the required movement
Covert imitation of actions Facilitated muscle activity
•Trace EMG activity found in response to watching same limbs of others move
Motor related brain rhythms•Rhythms blocked by motor activity are
also blocked by observation•Suggests equivalence of perceived and
performed action
Why do we covertly imitate? Might be due to the need for action
understanding…•To assist in categorizing the action•To uncover the purpose behind the behavior•To understand the antecedents of the action
(why do this? Affective state)•Makes sense if both sensory and motor
consequences are initiated Might be something to do with language
evolution•Area F5 & Broca’s area
Why do we covertly imitate? …or we might be trying to perceive what
we are seeing•Serves as an “emulator”
•Can perhaps be used to fill in missing or scratchy information
•Can perhaps be used to project likely movements of other’s body even when unsighted
•Info must permeate other systems beyond the motor system for this to work
p. 464
Why do we covertly imitate? Contrasts w/other (previous) proposals
•Others “postdictive”, this is predictive This requires allocentric representation
of body•Can map something watched in 3rd person as
experienced in 1st person•Clear tie ins for modeling, no?
p. 464
Perception is predictive Your favorite CD/playlist Similar prediction has been shown in
movement perception•“Representational momentum”
•Forward shift accepted, backward rejected (explain) – p. 465 has further examples
•Suggests perceptual extrapolation•“Filling in” – the x-y example•Also found for human movement (point
light)
Perceptual Prediction & Emulation How does it work?
•Internal model – forward model (Jordan)•Avoids dependence on feedback (important
when considering chronometry) in ballistic movements
Perceptual Prediction & Emulation How does it work?
•Emulators (again)•See definition on p. 466•Model of external system run internally, in real
time• Implies information about external world can be
had before it occurs•Emulation easier for simple patterns, or for very
familiar patterns•Supported by the idea that when outcomes are
unpredictable, representational momentum is absent (rock bouncing down hill)
Motor involvement in perceptual prediction There must be a match between what
is seen and what is experienced (what is experienced is what builds the emulator)•In the case of watching human bodies, the
match is pretty good – we have one, so we “know” how it behaves
Does covert imitation get used for perceptual prediction in human movement?
Motor involvement in perceptual prediction Motor activation that precedes the
related perceptual event•Pianists generate motor imagery prior to
the event that relates to it•Motor activation of a finger used to play a
note occurs prior to the note being heard in a familiar piece of music
Motor involvement in perceptual prediction Predictive capabilities of mirror
neurons•Mirror neurons that fire to a hand grasp
of an object also fire when the hand is seen about to grasp when going behind a screen…but only if it is known there is an object behind the screen
Motor involvement in perceptual prediction Influence of motor learning on
perception•When a particular movement pattern is
learned, subsequent recognition of similar movement patterns improves
Motor involvement in perceptual prediction Superior perceptual prediction by
viewing oneself•Idea here is that if the internal model is
based on an estimation of the external reality, then it should be best when the external reality is one’s own!•And it is borne out•People watching themselves perform better
in point light task identification then those watching others
Motor involvement in perceptual prediction Superior visual judgment for
possible movements•Perceptual prediction is influence by
motoric knowledge
So, um, what? Internal emulators imply perceptual
sophistication of unparalleled complexity
That these are unconscious implies there is a lot going on of which we are not aware
That the events invoke motor imagery is really important…see next week’s audio slides
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