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This article was downloaded by: [University of Regina]On: 04 September 2014, At: 23:53Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,UK
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The Role of Discourse andPerceptual Cues in the Choiceof Referential Expressions inEnglish Preschoolers, School-Age Children, and AdultsLudovica Serratrice aa School of Psychological Sciences The University ofManchester ,Published online: 13 Oct 2008.
To cite this article: Ludovica Serratrice (2008) The Role of Discourse and PerceptualCues in the Choice of Referential Expressions in English Preschoolers, School-AgeChildren, and Adults, Language Learning and Development, 4:4, 309-332, DOI:10.1080/15475440802333619
To link to this article: http://dx.doi.org/10.1080/15475440802333619
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LANGUAGE LEARNING AND DEVELOPMENT, 4(4), 309–332, 2008Copyright © Taylor & Francis Group, LLCISSN: 1547-5441 print / 1547-3341 onlineDOI: 10.1080/15475440802333619
HLLD1547-54411547-3341Language Learning and Development, Vol. 4, No. 4, August 2008: pp. 1–40Language Learning and Development
The Role of Discourse and Perceptual Cues in the Choice of Referential
Expressions in English Preschoolers, School-Age Children, and Adults
Referential Choice in EnglishSerratrice Ludovica SerratriceSchool of Psychological Sciences
The University of Manchester
Two studies investigated the choice of referential expressions in a referentialcommunication game for English-speaking adults, preschoolers, and young school-age children. The aim was to determine to what extent children and adults rely ondiscourse and perceptual information in their use of lexical noun phrases (NPs) vs.pronouns and null reference. Study 1 crossed two variables: the focus structure ofthe question asked (sentence focus vs. predicate focus) and the perceptual availabil-ity of the referent to the listener (listener looking vs. listener not looking). Study 2manipulated the number of referents (one vs. two) and the perceptual availability ofthe referent(s) to the listener (listener looking vs. listener not looking). The resultsshow that adults and children alike were very sensitive to the discourse cue pro-vided by the focus structure of the question asked; participants used more lexicalNPs with sentence focus constructions. The number of referents was also a reliablepredictor of the type of referential expression used, although even school-agechildren produced fewer lexical NPs than adults in two-referent contexts. Bycontrast, taking into account the perceptual availability of the referent to the listenerwas the variable that posed the largest number of difficulties to all groups ofchildren; even the oldest six-year-olds did not reliably produce a lexical NP whenthe listener could not see the referent. These findings contribute new experimentalevidence on children’s developing sensitivity to different types of discourse andperceptual cues in argument realization.
Correspondence should be addressed to Ludovica Serratrice, The University of Manchester,School of Psychological Sciences, HCD, Ellen Wilkinson Building, Manchester M13 9PL.E-mail: [email protected]
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INTRODUCTION
According to Clark & Marshall’s (1981) and Clark’s (1992) influential accounts,successful communication rests on the establishment of common ground; that is,on the shared representation of a situation model as “the sum of [the speakers’]mutual knowledge, mutual beliefs and mutual suppositions” (Clark, 1992). Theunambiguous identification of entities in the real world is a crucial aspect ofthe establishment of common ground. This process is both facilitated andcomplicated by the absence of a one-to-one correspondence between referentsand linguistic expressions, inasmuch as the availability of a multiplicity ofreferential expressions both allows and requires the speaker to make a choice.This choice will depend on a number of variables, such as the speaker’s and thelistener’s familiarity with the referent, the uniqueness of the referent, and its new-ness, to name but a few. Because the same referent can be identified by a numberof different expressions (e.g., “Mr Bush, the President, he”), the speaker’s task isto select the referential expression that will uniquely identify a referent for thelistener on the basis of their shared knowledge, beliefs, and suppositions. To do sosuccessfully, the speaker must attend to a range of cues available in the linguisticand in the extralinguistic context. Of particular interests here are different cuesthat contribute to the establishment of common ground, including information incurrent and prior discourse, possible competitors for the intended referent, andthe perceptual availability of the referent to the addressee.
Research on prelinguistic infants has shown that 12-month-olds are awareof whether something can be seen by someone or not and can modify theirbehavior accordingly (Brooks & Meltzoff, 2002; Moll & Tomasello, 2004).These rudimentary, pragmatic inferencing skills show children’s emergingability to take into account another’s perspective to establish common ground.Moreover, a growing body of evidence supports the idea that, at least in cer-tain circumstances, already in the early stages of multiword speech, childrencan use their addressee’s perspective when choosing a referential expression.Recent work on young preschoolers’ referential abilities in a range of lan-guages has shown that children as young as 2;6 select discourse-appropriatereferential expressions in naturalistic conversation with an adult interlocutor(Clancy, 1993; Allen, 2000; Guerriero, Cooper, Oshima-Takane & Kuriyama,2001; Skarabela & Allen, 2002; Skarabela, 2006; Allen & Schröder, 2003;De Cat, 2003, 2004; Guerriero, 2005; Serratrice, 2005). One of the commonfindings from these studies is that preschool children are significantly morelikely to use an overt referential expression, such as a lexical NP or a demon-strative pronoun, in cases in which the referent is not part of the commonground, rather than when it is. Skarabela & Allen (2002) and Skarabela(2006), for example, report that the four Inuktitut-speaking children in theirstudies were significantly more likely to omit arguments in the presence of
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joint attention. Children thus appear to be sensitive to the accessibility statusof the referent, not only from their own egocentric perspective, but they alsoseem to appreciate that their listener might see things differently if they do nothave access to the same type of information as they do.
Evidence from spontaneous, face-to-face interaction provides a wealth ofinformation for understanding how children negotiate referential choices (Allen,Skarabela, & Hughes, 2008). This type of setting has, however, some limitationsas young children and adults tend to talk about referents that are generally physi-cally present and perceptually available to both interlocutors (Tomasello, 1995;Clark & Wong, 2002). In such a supportive environment, children do not usuallyhave to assume that their perspective is very different from that of their adult lis-tener. Children’s ability to select appropriate referential expressions in contextsin which referents are not accessible to both speaker and listener may thereforehave been somewhat overestimated. A small number of experimental studieshave recently shed light on this issue by manipulating variables such as the pres-ence of the referent and of the listener, and the type of linguistic informationsolicited (Campbell, Brooks, & Tomasello, 2000; Wittek & Tomasello, 2005;Matthews, Lieven, Theakston, & Tomasello, 2006). The findings of the studiesconducted by Tomasello and colleagues show that children as young as 2;6 aresensitive to prior discourse in their selection of a referential expression; they aremore likely to use a lexical NP when the referent has not been previously men-tioned. There is also evidence that 3-year-olds can provide more informative ref-erential expressions as a function of their listener’s visual access to the referent.Both Campbell et al. (2000) and Matthews et al. (2006) report that from the ageof three, children did indeed use proportionally more nouns when they weredescribing an event to an experimenter who had not witnessed it. The use ofnouns for the benefit of one’s addressee requires the speaker to relinquish herown egocentric perspective and take her listener’s point of view in making herlinguistic choice.
Crucially, the evidence for children’s ability to assess another’s perspectivein the referential communication studies reviewed above is mediated by the typeof question the children were asked. A general question such as, “Whathappened?” requires an answer where the subject and the predicate form aninformational unit in which the subject has no previously mentioned discoursereferent, before it enters into a focus relation with the predicate in the givenutterance (Lambrecht, 1994). These sentence-focus constructions aretherefore likely to include a subject that will be realized by a maximallyinformative expression, such as a lexical NP. In essence, regardless ofwhether the speaker asking “What happened?” has witnessed the event or not,the expectation is that the answer should contain information on the event orstate of affairs (expressed by the predicate) and on the participants (expressedby lexical NPs). This expectation is indeed borne out by the findings of
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Matthews et al.1 However, although the children in their study did useproportionally more nouns when the addressee could not see the video, theyalso provided a substantial proportion of nouns in contexts when the addresseedid have access to the video (approximately 55–80% of the time). The fact thatthe children used so many nouns in a context in which a less informative formwould have sufficed indicates that the discourse cue provided by the sentence-focusconstruction of the general question played a greater role than the perceptual cue pro-vided by the visual availability of the referent to the addressee. If this inferenceis correct it is not entirely clear that the children’s use of nouns in the conditionin which the experimenter could not see the video was solely motivated by theirability to take their interlocutor’s perspective into account. Because both thefocus structure of the question asked, and the perceptual unavailability of thereferent to the listener called for the use of lexical NPs, it is difficult to decide towhat extent children relied on one or the other sources of information. A morestringent test of children’s perspective-taking abilities would be to pit thediscourse cue (sentence-focus questions “What happened?” vs. predicate-focusquestions “What did X do?”) against the perceptual cue (addressee looking atreferent vs. addressee not looking at referent), to tease apart the relativecontribution of each in the selection of referential expressions.
The purpose of the present studies was to assess the extent to which preschooland school-age children can choose discourse-appropriate referential expressionsin the face of converging and conflicting discourse and perceptual cues. In twoexperiments, children looked at a series of colored drawings and played a versionof bingo with an adult experimenter. Their task was to answer general sentence-focus questions and specific predicate-focus questions about the picturespresented on a laptop computer, so that the experimenter could find the largestpossible number of matching pictures in a folder of her own. Study 1 crossed twovariables: the type of question asked (general vs. specific) and the perceptualavailability of the referent to the experimenter while the picture was displayed onthe laptop screen (“listener looking” vs. “listener not looking”). Study 2 manipu-lated the number of animate referents displayed in the pictures (one vs. two) andthe perceptual availability of the referent to the experimenter.
1By contrast, the perceptual availability of the referent to the listener is going to make asignificant difference when the question asked has a predicate focus (e.g., “What’s that persondoing?”). In the answer to this type of question the subject is old information and as such it islikely to be expressed by a pronoun or even null reference. The use of a reduced expression ispragmatically appropriate in the case in which both interlocutors can see the referent. However,in the case in which the question “What’s that person doing?” is asked by someone who cannotsee the referent and needs more precise information on the identity of the person in question, asin the case of Study 1, the respondent should try and use a more informative expression such as alexical NP.
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STUDY 1
In this study questions were of two types: general (“What’s happening there?”)and specific (“What’s that person doing?”). In previous elicitation studies with2-and 3-year-olds using toy props, general sentence-focus questions such as,“What’s happening?” or “What do we need to get?” typically yielded moreanswers containing nouns than questions already including a definite NP such as“What happened to the clown?” or “What did the clown do?” Children weremore likely to respond to these questions with null reference. The current studyused a sentence-focus question of the “What’s happening?” general-type used inprevious studies, and a modified version of the specific predicate-focus questionto include a more general subject NP (“that person”), rather than a definite NPincluding a specific noun (e.g. “the clown”) to identify the referent in question.The latter manipulation meant that children were still asked a question about aspecific individual, but without a label for it. This manipulation was justifiedbecause, as the experimenter explained to the participants, each of the drawingscontained a different person doing something. The experimenter, therefore, knewthat a person would be in the picture, although she did not necessarily knowwhich one. The rationale for this modification was to investigate whether chil-dren operate at the level of the focus structure information provided by differentinterrogative constructions (“What’s happening?” vs. “What’s X doing?”), orwhether they rely exclusively on a referent’s previous mention. If indeed theyomit nouns in their answers only when they have heard them verbatim in apreceding question, the expectation is that a question such as “What’s that persondoing?” should elicit as many answers including subject NPs, as a general questionsuch as “What’s happening?” If, however, children are indeed sensitive to theinformation structure of the question, we would expect that even with a rather gen-eral subject such as “that person,” children ought to provide fewer lexical NPs inresponse to “What’s that person doing?” than to “What’s happening?” questions.
The second variable manipulated in this study, fully crossed with the first, isthe effect of the perceptual availability of the referent to the listener; that is,whether the experimenter was looking at the pictures together with theparticipants or not.
Study 1 included four conditions: general question/“listener not looking”(condition 1), specific question/“listener looking” (condition 2), general question/“listener looking” (condition 3), and specific question/“listener not looking”(condition 4). If children are sensitive to the referent’s perceptual accessibility tothe listener, they ought to produce maximally informative referential expressions(lexical NPs) when the listener is not looking at the picture (conditions 1 and 4),regardless of the type of question asked. When the listener is looking (conditions 2and 3), the type of question asked ought to matter; more lexical NPs should be usedanswering a general question (condition 3) than a specific question (condition 2).
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Methods
Participants. Seventy typically developing, monolingual English-speakingchildren and 23 monolingual English-speaking adults participated in the study.The children were divided into three groups: a 3-year-old group (N = 19) with amean age of 3;6 (range 3;3–3;8), a 5-year-old group (N = 27) with a mean age of5;5 (range 5;3–5;7), and a 6-year-old group (N = 24) with a mean age of 6;3(range 6;1–6;5).
Materials and design. The stimuli included 26 colored drawings, repre-senting an animate agent acting upon an inanimate patient (e.g. a girl eating apiece of cake; a cook peeling a carrot); two were practice items and 24 were testitems. There were four versions of each test item in which different characterswould perform the same target action (a girl eating a piece of cake, a boy eating apiece of cake, a woman eating a piece of cake, a man eating a piece of cake).Children were randomly assigned to one of the lists. The drawings wereembedded in PowerPoint presentations and were presented on a widescreenlaptop computer in two different conditions. In the “listener looking” conditionthe experimenter and the participant were sitting next to each other facing thecomputer screen. In the “listener not looking” condition the experimenter turnedher back to the participant and to the computer and sat facing in the oppositedirection. She explained that she had to turn her back so that they could be abso-lutely certain that she could not see the pictures. For each condition, half of thequestions asked by the experimenter were “What’s happening there?” and halfwere “What’s that person doing?” The order of presentation was counterbalancedso that half of the participants took part in the “listener looking” condition first,and half in the “listener not looking” condition first. The participants’ responseswere audio-recorded on the laptop used to present the stimuli.
Procedure
The participants were tested individually on school and university premises.The experimenter explained to the children that they would be looking at somepictures on the computer and would play a version of bingo. The aim of the gamewas to match the pictures on the laptop screen with those contained in a folderheld by the experimenter. The experimenter showed the children a foldercontaining a copy of the pictures that they would see on the screen. She explainedthat the folder contained all of the pictures that they were going to look at andsome others as well. The experimenter made it clear to the children thatshe did not know exactly what pictures they would see in the presentation, as thepictures were chosen by the computer. In actual fact, the participants wererandomly assigned to one of four lists by the experimenter who followed a
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written script to ensure consistency across participants. Because the experimenterinteracted with the participants, she was not blind to the condition they were in.However, she provided feedback only during the initial practice; during the testitems she read aloud the question that was assigned to the picture in the script anddid nothing more, thus minimizing the risk of biasing the participants’ responses.The experimenter explained to the children that for half of the pictures she wouldsit next to them and they would look at the pictures together; for the other halfshe would turn her back to the children and they would have to help her find theright picture in her folder. She added that when she could not see the pictures,they would have to be extra helpful when answering her questions; they wouldhave to tell her who was doing what every time so that she could choose the rightdrawing. The children were then told that there were four pictures in the experi-menter’s folder for each action, and they were shown the four cake-eatingpictures. No baseline vocabulary knowledge was established prior to the test forthe child participants due to the extremely basic nature of the type of nouns thechildren were required to provide (e.g., “the girl,” “the man,” “the old woman”).There was only one picture portraying a ghost that was not successfully identifiedby some of the younger children. This lexical gap was recognized early on in theexperiment; therefore, after the practice session, the experimenter made sure thatthe children knew the label for “ghost.” The adults were given the same set ofinstructions. After this introductory explanation the participants were shown twopractice pictures; the experimenter provided feedback until the desired referentialexpression was produced.
Coding. The participants’ responses were digitally audio-recorded and latercoded by the experimenter. Twenty percent of transcripts were checked by anindependent coder; intercoder agreement was 100%. Only referential expressionsfor subject referents were coded for the purpose of this study. The coding catego-ries were the following: indefinite and definite lexical NP (“a woman is openingthe door,” and “the woman is opening the door,” respectively), subject personpronoun (“she is opening the door”), null reference (“opening the door”), indefi-nite pronoun (“someone is opening the door”), repetition of “that person” fromthe previous question (“that person is opening the door” ).
Results
Figure 1 reports the mean proportion of lexical NPs, null reference, and personalpronouns in the four conditions for the four age groups. On the horizontal axisthe discourse cue has been identified as D (general question = D+; specificquestion = D-), and the perceptual cue as P (listener not looking = P+; listenerlooking = P-). From left to right the charts display the two conditions in which thecues converge (condition 1: D+P+, general question/“listener not looking”;condition 2: D-P-, specific question/“listener looking”), followed by the two
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conditions in which the cues diverge (condition 3: D+P-, general question/“listener looking”; condition 4 D-P+, specific question/“listener not looking”).
The adults behaved as expected. In condition 1 (D+P+), the convergence ofthe discourse and the perceptual cues called for a maximally informative referen-tial expression, and the adults produced a majority of lexical NPs. In contrast,when the cues converged in condition 3 (D-P-) and required a reduced referentialexpression, two-thirds of the adults’ answers included a pronoun or nullreference. The adults used pronouns and null reference in this condition 33% and34% of the time, respectively, an indication that the forms in this context are
FIGURE 1 Study 1: the mean proportion of lexical NPs, null reference, and pronouns in thefour conditions. Note that some of the conditions do not add up to 1, because responsescontaining referential forms other than lexical NPs, null reference, or personal pronouns werenot included in the analysis.
Lexical NPNull referencePronoun
D+P+ D–P– D+P– D–P+Condition
D+P+ D–P– D+P– D–P+Condition
D+P+ D–P– D+P– D–P+Condition
D+P+ D–P– D+P– D–P+Condition
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Adults Lexical NPNull referencePronoun
3-year-olds
Lexical NPNull referencePronoun
5-year-olds Lexical NPNull referencePronoun
6-year-olds
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largely interchangeable. When the cues diverged, the adults’ answers stillincluded a majority of lexical NPs. In condition 3 (D+P-) the lexical NPs werejustified by the sentence-focus structure of the general question. In condition4 (D-P+) they were necessary because the listener could not see the pictures. Insum, mature speakers resorted to null reference only in the condition in whichboth the cue provided by the discourse and the cue provided by the perceptualavailability of the referent to the listener converged to require a minimallyinformative referential expression (D-P-).
The children’s behavior was somewhat different from the adults’, and ageplayed a significant role in their choice of referential expressions, depending onwhether the discourse and perceptual cues converged or diverged. Overall, the3-year-olds produced a much smaller proportion of lexical NPs than did the olderchildren and adults. They relied extensively on null reference in all conditions,and dramatically more so in the two conditions in which the question wasspecific, but they also used more pronouns than the older children. In condition 1(D+P+), the 3-year-olds produced a nontrivial proportion of lexical NPs,alongside null reference and pronouns. In condition 2 (D-P-) they hardly usedany lexical NPs and largely relied on null reference and a small proportion ofpronouns. In condition 3 (D+P-), when the perceptual cue called for either a nullreference or a pronoun, but the discourse cue required a lexical NP, the 3-year-oldsstill largely resorted to null reference and pronouns, although they also providedlexical NPs in approximately a third of their answers. The perceptual cue wasalmost completely disregarded by the younger children in condition 4 (D-P+)where lexical NPs accounted for a very small proportion of the referentialexpressions used.
In contrast to the pattern observed for the 3-year-olds, the behavior of theolder children (5- and 6-year-olds) was much closer to the adults’. They wereconsiderably more successful at selecting appropriate referential expressions, notonly in the two conditions in which the cues converged, but also in the twoconditions in which they diverged. In condition 1 (D+P+) both groups producedlexical NPs almost exclusively, and in condition 2 (D-P-) the majority of answersincluded either null reference or a pronoun. When cues diverged in condition3 (D+P-), like the adults they opted for lexical NPs in the vast majority of cases.Neither the 5- nor the 6-year-olds, however, were as successful as the adults inproviding lexical NPs in condition 4 (D-P+) when the perceptual cue required theuse of a maximally, informative referential expression for the benefit of thelistener.
To test for the statistical significance of these patterns in the participants’responses, the data were analyzed in a 2 × 2 × 4 ANOVA with a mean proportionof lexical NPs as the dependent variable, question type (general/specific), andperceptual availability of the referent to the listener (“listener looking”, “listenernot looking”) as the within-subjects variables, and age (3-year-olds, 5-year-olds,
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6-year-olds, and adults) as the between-subjects variable. The highly significantmain effect for question type (F(1,89) = 235.87, p <.001, partial η2 = .72)confirmed that, across participants, general questions elicited more lexical NPsthan specific questions. The significant effect of the perceptual availability of thereferent to the listener (F(1,89) = 89.78, p < .001, partial η2 = .50) showed that,overall, participants produced more lexical NPs when the experimenter could notsee the referent than when she could see it. The difference between the four agegroups was highly significant (F(3,89) = 33.64, p <.001, partial η2 = .53)showing that more lexical NPs were produced by the adults and the older-agedchildren. Bonferroni posthoc tests showed that the only nonsignificantdifferences were between 5- and 6-year-olds (p >.05), and between 5-year-oldsand adults (p >.05), while the other group differences were all highly significant(p < .001).
There was a significant interaction between question-type and the perceptualavailability of the referent to the listener (F(1,89) = 62.75, p <.001, partial η2 = .41).A simple effects analysis indicated that significantly more lexical NPs were pro-duced when the listener could not see the referent when the question was general(p < .001), and specific (p < .001). This confirms that, regardless of the discoursecue, the perceptual cue exerted a strong influence on the choice of referentialexpression, although this was not equally true for all age groups. There was alsoa significant interaction between question type and age (F(3,89) = 9.24, p <.001,partial η2 = .23), and a significant interaction between perceptual availability ofthe referent to the listener and age (F(3,89) = 12.57, p <.001, partial η2 = .29).These two-way interactions were subsumed under a three-way interactionbetween question-type, perceptual availability, and age (F(3,89) = 4.44, p <.01,partial η2 = .13). Four one-way ANOVAs were performed to explore the mean-ing of the three-way interaction, one for each condition, with the mean proportionof lexical NPs as the dependent variable and age as the independent variable. Incondition 1, in which the cues converged and required the use of a lexical NP(D+P+), there was a significant difference among the four groups (F(3,89) = 34.81,p <.001, partial η2 = .53). Bonferroni posthoc tests confirmed that although3-year-olds produced significantly fewer lexical NPs than all other groups(p <.001), no other significant differences were observed. Unlike the older chil-dren and the adults, even when both cues converged and required the use of amaximally informative referential expression, the 3-year-olds in this study failedto produce lexical NPs consistently. In contrast, in condition 2, in which bothcues required either a pronoun or possibly null reference (D-P-), there were nosignificant differences such as a function of age (F(3,89) = 2.68, p > .05, partialη2 = .08). Resorting to null reference or to the use of a pronoun was clearly lessdemanding even for the younger children in this context. In condition 3 (D+P-),where the discourse cue was pitted against the perceptual cue and the optimalreferential expression was a lexical NP, there was a significant difference among
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the four age groups (F(3,89) = 11.79, p <.001, partial η2 = .28). Bonferroniposthoc tests revealed that although the 3-year-olds produced significantly fewerlexical NPs than all the other groups (p <.001), no other significant differenceswere found. Once again, the 3-year-olds were significantly less consistent thanthe older children in the use of lexical NPs. Finally, condition 4 (D-P+) pitted thediscourse cue against the perceptual cue, and the latter demanded thatrespondents use a lexical NP to allow the listener to unambiguously identify thereferent in question. Here, too, there was a significant effect of age group(F(3,89) = 33.57, p <.001, partial η2 = .53). Bonferroni posthoc tests showed thatthe only nonsignificant difference was between 5- and 6-year-olds. As childrengot older they produced more lexical NPs in this condition. Nevertheless, evenby the age of six, they were significantly less likely than the adults to use therequired maximally informative expression in this context.
To verify whether the order of the listener condition in which the participantswere tested affected the proportion of lexical NPs used, additional tests wereperformed. Each age group was divided into two groups according to whether thetesting session started with the “listener looking” or the “listener not looking”condition, and a series of Mann-Whitney U tests was performed for each of thefour conditions. There were no significant differences in any of the conditions forany of the groups showing that the listener condition in which the participantsstarted did not affect their response pattern.
The results of Study 1 show a clear effect of discourse in the form of the focusstructure of the question, with general questions eliciting a significantly largerproportion of lexical NPs than specific questions. All the participants, includingthe younger children, used fewer lexical NPs to identify a referent answering aspecific question, even though the referent itself was not named in the question.This suggests that children are sensitive to the type of information requested onthe basis of the focus structure of the question, and that their choice of referentialexpression does not depend purely on a referent’s previous discourse mention.
The effect of the perceptual availability of the referent to the listener is alsoclear. The adults’ responses confirmed our predictions: when the experimentercould not see the pictures, the adult participants used a significantly largerproportion of lexical NPs than when she could see them. Crucially, they did soregardless of the type of question asked. Even when the question was specificand the focus structure of the question was biased towards a less informativereferential expression, such as a pronoun, the adults were still very aware ofthe need to be as informative as possible for the experimenter’s benefit. Thechildren’s behavior is somewhat different from the adults’. The pattern in Figures1b–1d is quite clear; access to the referent on the part of the listener did notsignificantly affect the 3-year-olds’ production of lexical NPs, only the type ofquestion did. By contrast, the 5- and the 6-year-olds behaved differently from theyounger children and more like the adults. When the question was general, in
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both the “listener looking” and the “listener not looking” conditions, the older chil-dren consistently provided lexical NPs in the vast majority of cases. Interestingly,when the question was specific the older children provided more lexical NPs in the“listener not looking’ than in the “listener looking” condition, suggesting that theycould override the information structure bias of the question-type to some extentwhen they were required to be as informative as possible. Nevertheless, in contrastwith the adults, neither the 5- nor the 6-year-olds produced as many lexical NPs in the“listener not looking” condition with a specific question, as they did when the ques-tion was general—an indication that, unlike the adults, when the discourse cue (focusstructure of the question) was pitted against the perceptual cue (listener’s visualaccess to the referent), their choice of referential expression was determined largelyby the effect of the discourse cue and not by the effect of the perceptual cue.
STUDY 2
The results of study 1 show that children as young as three are sensitive to the typeof linguistic information requested and that, at least in a limited number of con-texts, they can select discourse appropriate referential expressions. At the sametime, children as old as six do not use a lexical NP for the benefit of a listener whohas no visual access to the referent if the information structure of the question callsfor a more minimal referential expression, such as a pronoun or null reference.
The aim of Study 2 was to further explore children’s sensitivity to a differentsource of perceptual information that may affect their choice of referentialexpressions. This second experiment investigated the effect of the number of ref-erents present in the scene, and the interaction between this source of perceptualinformation and the listener’s access to it. Evidence from elicited production sug-gests that children as young as four can refer to similar members of a set throughrestrictive modification (e.g. “the blue frog,” “the frog on the mirror”) (Hurewitzet al., 2001). This study explored whether children from three to six couldlinguistically distinguish two nonidentical entities in a referential scene (e.g. aboy and a girl, a man and a woman).
The questions asked were always specific. Similar to Study 1, they containedthe subject NP “that person/those people,” rather than a more specific NP clearlyidentifying the target referents (e.g. “the man”/“the children”). The two variableswere fully crossed to yield four conditions, two of which (condition 2 andcondition 4) were the same as in Study 1: condition 1 (two referents/“listener notlooking”), condition 2 (one referent/“listener looking”), condition 3 (tworeferents/“listener looking’), condition 4 (one referent/“listener not looking”).The prediction was that mature speakers would be sensitive first and foremost towhether the referent was perceptually available to the listener or not; i.e., whetherthe experimenter was looking at the picture together with the participants or not.
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Conditions 1 and 4 therefore were expected to yield the largest proportion oflexical NPs. In condition 2, where there was only one referent that was equallyaccessible to the speaker and the listener, the largest proportion of pronouns andnull reference was expected. Finally, in condition 3, gender-marked pronounsshould in principle be sufficient to unambiguously identify the two referents.
Participants
A subset of the children who participated in Study 1 took part in Study 2 on a dif-ferent day. A total of 60 children and 20 adults took part in Study 2. This studyincluded a group of 3-year-olds (N = 19) with a mean age of 3.6 (range 3.3–3.8),a group of 5-year-olds (N = 21) with a mean age of 5.7 (range 5.4–5.9), and agroup of 6-year-olds (N = 20) with a mean age of 6.2 (range 6.0–6.4).
Materials and Design
The drawings were similar to those used in Study 1, with animate human agents act-ing upon inanimate patients, with the exception that in this second study, the numberof human agents varied. In half of the pictures there was only one human agent act-ing upon an inanimate patient (e.g. a man reading a newspaper), and in the other halfthere were two human agents of different genders engaged in separate actions ondifferent inanimate patients (e.g. a girl eating ice-cream and a boy drinking a glass ofjuice). The questions posed by the experimenter were “What’s that person doing?” ifthere was only one animate agent, and “What are those people doing?” if there weretwo. Because the pictures with one human agent were identical in the two studies, inStudy 2 the participants were assigned to a different list from Study 1. The order ofpresentation of the one-referent and the two-referent pictures in the two “listenerlooking”/“listener not looking” conditions was blocked so that participants would beasked specific questions about six one-referent pictures, followed by specific ques-tions about six two-referent pictures. The order of one- and two-referent pictures inthe two conditions was counterbalanced across participants. The experimenter madeit clear to the participants that she had different lists for the participants and that foreach of them she knew whether they were looking at a picture with one or two peo-ple, but she did not know who these people were and what they were doing. In orderto match them to the right picture the participants would have to tell her exactly whowas in the picture and what they were doing.
Procedure
The procedure followed in Study 2 was identical to the protocol in Study 1. Theparticipants who started with the “listener looking” condition in Study 1 startedwith the “listener not looking” first in Study 2, and vice versa.
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Coding
The participants’ responses were digitally audio-recorded and later coded by theexperimenter. Twenty percent of the transcripts were checked by an independentcoder; intercoder agreement was 98%. Disagreements were resolved by listeningto the audio files together. Only referential expressions for subject referents werecoded for the purpose of this study. The coding categories were the same as inStudy 1. In addition, they were able to use “One/the other” (e.g. “One is reading apaper and the other is writing a letter”).
Results
Figure 2 reports the mean proportion of lexical NPs, “One/the other,” null refer-ence, and personal pronouns in the four conditions for the four age groups. Onthe horizontal axis the cue pertaining to the number of referents is identified as R(two referents = R+; one referent = R-), and the perceptual cue as P (listener notlooking = P+; listener looking = P-). From left to right the charts display the twoconditions in which the cues converge (condition 1: R+P+, two referents/“listenernot looking”; condition 2: R-P-, one referent/“listener looking”), followed by thetwo conditions in which the cues diverge (condition 3: R+P-, two referents/“listener looking”; condition 4: R-P+, one referent/“listener not looking”).
The results for the two one-referent conditions replicate the findings of Study 1.In the following, therefore, I will focus only on condition 1 (R+P+), in which thetwo cues converged and required a maximally informative referential expression,and on condition 3 (R+P-) in which the two cues diverged and the referent cueminimally called for two gender-marked pronouns. In condition 1 the adultsbehaved as expected and used a majority of lexical NPs and a small proportion ofpronouns. In condition 3 they used predominantly lexical NPs rather than gender-marked pronouns, which would have been sufficient to unambiguously identifythe two referents because the listener had access to the pictures. The 3-year-oldsmostly resorted to null reference in both condition 1 and 3, but they showed somesensitivity to the presence of two referents when they used “One/the other” tocontrast between the two. The older children used an increasingly larger propor-tion of lexical NPs in condition 1. Both the 5- and the 6-year-olds also used anontrivial proportion of “One/the other” in this condition in which the referentswere not visible to the listener, thus failing to fully comply with the listener’sneeds. In condition 3, the situation is very similar for both groups of olderchildren; more lexical NPs, hardly any pronouns, and a proportion of “One/theother” comparable to condition 1, which in this condition was an acceptablechoice as the listener had visual access to the pictures.
To test for the significance of these findings, the data were analyzed in a 2 × 2 × 4ANOVA with mean proportion of lexical NPs as the dependent variable. Number
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of referents (one/two), and perceptual availability of the referent to the listener(“listener looking”/“listener not looking”) were the within-subjects variables, andage (3-year-olds, 5-year-olds, 6-year-olds, and adults) was the between-subjectsvariable. There was a highly significant main effect of the number of referents(F(1,76) = 71.40, p <.001, partial η2 = .48) confirming that, overall, conditions withtwo referents elicited more lexical NPs than conditions with one referent. Theeffect of the perceptual availability of the referent to the listener was also highlysignificant (F(1,76) = 81.40, p <.001, partial η2 = .51), showing that, in general,
FIGURE 2 Study 2: the mean proportion of lexical NPs, ‘One/the other’, null reference andpronouns in the four conditions. Note that some of the conditions do not add up to 1, asresponses containing referential forms other than lexical NPs, null reference or personalpronouns were not included in the analysis.
Lexical NPOne/the otherNull referencePronoun
AdultsLexical NPOne/the otherNull referencePronoun
3-year-olds
Lexical NPOne/the otherNull referencePronoun
5-year-oldsLexical NPOne/the otherNull referencePronoun
6-year-olds
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participants were more likely to use a lexical NPs when the listener could notsee the referent than when she could. Age also played a significant role(F(3,76) = 25.50, p <.001, partial η2 = .50), confirming the observation thatmore lexical NPs were produced by older children and adults. Bonferronipost-hoc tests indicated that there were no significant differences either betweenthe 3- and the 5-year-olds, or between the 6-year-olds and the adults, while all theother pairwise comparisons showed significant differences (p <.01).
There was a significant interaction between number of referents and percep-tual availability of the referent(s) to the listener (F(1,76) = 37.36, p <.001, partialη2 = .33). A simple effects analysis indicated that significantly more lexical NPswere produced when participants could not see the referent, both when thepicture included one referent (p < .001) and when it included two (p < .001), thusconfirming the privileged status of the accessibility perceptual cue.
Two significant interactions between the number of referents and age(F(3,76) = 4.70, p <.01, partial η2 = .15), and between perceptual availability ofthe referent and age were also found (F(3,76) = 7.58, p <.001, partial η2 = .23).These interactions were subsumed by a three-way interaction between number ofreferents, perceptual availability of the referents, and age (F(3,76) = 5.79, p <.01,partial η2 = .18). This three-way interaction shows that there were agedifferences in the four different conditions as a function of the convergence ordivergence of cues. To further explore the meaning of this finding, four follow-up, one-way ANOVAs were conducted, one for each condition, with the meanproportion of lexical NPs as the dependent variable and age as the independentvariable. The findings from the two one-referent conditions (condition 2 and 4)replicated the results from the two conditions with a specific question in Study 1.In condition 2 there were no significant differences as a function of age(F(3,76) = 2.09, p > .05, partial η2 = .07), showing once again that when the twocues converged and required a maximally reduced expression, all groups reliedeither on null reference or on pronouns. In condition 4 there was a significanteffect of age (F(3,76) = 28.83, p <.001, partial η2 = .53). Bonferroni posthoc testsshowed that the only nonsignificant difference was between 5- and 6-year-olds. Aspreviously found in Study 1, there was an increase in children’s ability to provide alexical NP when the presence of only one referent and the focus structure of the ques-tion were pitted against the perceptual unavailability of the referent to the listener.
In condition 3 (R+P-), where the number of referents cue was pitted againstthe perceptual availability cue, the effect of age was significant (F(3,76) = 13.98,p <.001, partial η2 = .35). Bonferroni posthoc tests revealed no significant differ-ences between 3- and 5-year-olds, or between 6-year-olds and adults. The remain-ing pairwise comparisons were significant (p <.01). The 3- and the 5-year-oldswere significantly less likely than the older children and the adults to provide alexical NP in the two-referent condition when they could see the picture.However, rather than relying on gender-marked pronouns as another viable
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alternative, they overwhelmingly resorted to null reference. The same pattern ofresults was found in condition 1 when the two cues converged (R+P+) and alexical NP would have been the most pragmatically appropriate choice. Sig-nificant differences existed as a function of age (F(3,76) = 20.58, p <.001,partial η2 = .44), but no significant differences existed between 3- and5-year-olds or between 6-year-olds and adults, according to Bonferroni posthoctests. Once again it appears that the two-referent contexts were likely to elicitsignificantly more lexical NPs only for older children and adults, while thisperceptual cue seems much less important for younger children.
As in Study 1, Mann-Whitney U tests for each of the four conditions revealedno significant order effects for when in the study the “listener looking” conditionoccurred.
There are three clear sets of findings from Study 2. First, more lexical NPswere produced overall when the picture included two rather than one referent,thus showing that this perceptual cue played a role in the participants’ choice ofreferential expression, although there were age differences. Second, the percep-tual availability of the referent also made a significant difference, regardless ofwhether the context included one or two referents. When the experimenter couldnot see the pictures, the older children and the adults predominantly used lexicalNPs so that she could unambiguously identify the picture they were looking at inher own folder. When both the participants and the experimenter had visualaccess to the pictures, the number of referents had a clear effect on the olderchildren’s and on the adults’ referential choices, regardless of the fact that theywere being asked a specific question on both occasions. Similar to the findingsfor the specific question/“listener looking” condition in Study 1, when there wasonly one referent in the picture, all the participants tended to use less informativeexpressions, such as personal pronouns or null reference. However, when theyhad to make reference to two entities rather than one, they chose to use moreinformative expressions, largely lexical NPs for the 6-year-olds and the adults.This is in line with the findings from elicited production tasks in Hurewitz et al.(2001) where children 4- and five-years-old successfully disambiguated twoentities in the same referential scene on the basis of either location or an attribute.
A third finding relates to the role of age in the developing sensitivity to boththe number of referents cue and the perceptual availability cue. The 3-year-oldchildren used a small number of lexical NPs overall. Although they producedmarginally more nouns in the “listener not looking” conditions, and when there weretwo referents, these differences were not statistically significant. Neither the visualaccess to the referent on the part of the listener, nor the number of referents affectedthe younger children’s choice of referential expressions in any meaningful way.
Another noteworthy finding related to the responses in the two-referents con-text in the “listener looking” condition is the underuse of pronouns. In principle,a gender-marked pronoun would have been sufficient to disambiguate the two
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referents when the experimenter could see the pictures; nevertheless, the adultsand the 6-year-olds used lexical NPs almost exclusively, the 3-year-olds privi-leged null reference, and the 5-year-olds’ referential expressions were equallydistributed between null reference, lexical NPs, and “One /the other.” The use of“One/ the other” to disambiguate two referents of different genders engaged indifferent actions seems to be an intermediate strategy used by children who arebeginning to appreciate the need to mark the contrast linguistically, but do not yetdo so using the maximally informative expression available, i.e., nouns. Arnold& Griffin (2007) report a similar two-character effect in two experiments inwhich adult participants were asked to continue stories about pictures that werepresented in two successive panels. Because, in all conditions the characters inthe first panel were of different gender, the use of pronouns in the continuation oftheir stories would have been pragmatically felicitous and interpretable to thelistener. The results of both experiments however showed that speakers tended touse proper names instead of pronouns in the two-character conditions. Arnold &Griffin argue that the two-character effect is evidence that the use of propernames is motivated by speakers’ internal processing needs, rather than by theneed to make the referent unambiguously identifiable by their listener. Theyfurther claim that their results are consistent with the notion that accessibility isaffected by cognitive pressures. In the case of a two-character context, tworeferents compete for attentional resources in the mind of the speaker, and thustheir activation level is lowered, making it more likely that a proper name or alexical noun phrase would be used instead of a more reduced, but pragmaticallyappropriate, pronominal expression. Although the stimuli in the current studywere different from Arnold & Griffin’s, our participants still had to identify twoentities of different gender in response to a specific question where a pronounwould have been perfectly pragmatically felicitous. In the same vein we proposethat the presence of two entities imposes demands on the speaker’s mentalrepresentations that are not found in one-referent contexts.
As far as other referential expressions are concerned, null reference featuresprominently in the two-referent conditions for the 3-year-olds (56%–63%), and itis also a referential strategy used by the 5-year-olds to some extent (34%–38%),while 6-year-olds and adults hardly ever use null reference in these conditions.Once again, a developmental trend emerges with respect to the ability to choosediscourse-appropriate expressions that unambiguously identify one or more ref-erents for the benefit of the listener.
GENERAL DISCUSSION
The aim of the present studies was to investigate the relative contribution ofdiscourse and perceptual cues in the establishment of common ground through
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the choice of referential expressions in preschoolers, young school-age children,and adults in an experimental setting.
Sensitivity to Information Structure
The findings show a clear age divide between younger children (3-year-olds),older children (5-year-olds and 6-year-olds), and adults in terms of the ability tounambiguously identify a referent for the benefit of the listener. The 3-year-oldswere not as successful as the older children when they had to take into accountperceptual cues in the referential scene, such as the number of referents and thevisual availability of said referents to the listener. They were, however, sensitiveto the information structure of the questions they were being asked, and they usedsignificantly more informative expressions in the form of lexical NPs when ageneral question called for a sentence-focus construction (“What’s happeningthere?”), than when a specific question required a predicate-focus construction(“What’s that person doing?”). Interestingly, the use of “that person” in thespecific question did not prevent any of the participants from opting for morereduced expressions, such as pronouns and null reference in the “listener look-ing” condition, in line with the results obtained by Campbell et al. (2000), whonamed the referent in their specific question (e.g. “What’s the ball doing?”), andwith those of Matthews et al. (2006), who instead named the referent inconjunction with a general question (e.g. “Was that the clown? Whathappened?”). Matthews et al. rightly observed that children’s differentialresponses to “What happened?” and to “What’s the ball doing?” questions mightsimply reflect an ad hoc strategy based on lexically specific knowledge. By thisrationale the answer to a question such as, “What did X do?” is pronoun/null ref-erence + verb, while the answer to the question “What happened?” must includea full noun. My search of the Manchester corpus (Theakston, Lieven, Pine &Rowland, 2001) showed that out of 140 maternal questions of the format “What’s(the) + noun V-ing?” 104 were accounted for by “What’s (the) + noun doing?”confirming that the verb doing has a 74% probability of filling the V-ing slot inthis construction, thus making “What’s (the) + noun doing?” a highly predictablelexically-specific construction. Study 1 did the opposite of what Matthews et al.did in their study, it kept the discourse information structure cue and eliminatedthe previous mention of the referent cue. The findings show that the informationstructure of the question does play a role because the participants used a largerproportion of less informative expressions in their answer to the predicate-focusquestions, even in the absence of a previous mention of the referent. The currentfindings, added to Matthews et al., show that children respond both to the infor-mation structure of the question and to the previous mention of a referent. In aquestion such as, “What’s the clown doing?” both the previous mention cue andthe information structure cue converge, thus increasing the chances that the
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answer will contain a less informative referential expression, but even the pres-ence of only one of the two cues is sufficient to elicit the same type of response.As Allen (2000) observed in the case of her naturalistic Inuktitut data, thereseems to be a hierarchical and/or cumulative effect of informativeness features,whereby some cues are strong enough to require a more informative referentialexpression in their own right, while others can do so only when they occur simul-taneously with other cues.
Converging and Conflicting Cues: The Relative Weight of Discourse and Perceptual Availability
Both studies reported here deliberately crossed variables so that cues wouldeither converge or conflict with one another. This design allowed the evaluationof the relative contribution provided by discourse and perceptual cues and howthis changes over the course of development. Both studies had two conditions inwhich the two cues converged and two conditions in which they were in conflict.In both studies the cumulative effect of converging cues increased the likelihoodthat either maximally or minimally informative expressions would be chosen bythe respondents. The conditions in which the cues diverged are more interestingand crucial than in the evaluation of how different sources of information affect thechoice of referential expressions over time. The results for Study 1 clearly show thatthe discourse cue is stronger than the perceptual cue when the question has a sen-tence focus structure. Even in the presence of the listener, when a pronoun wouldhave been sufficient to unambiguously identify the referent, the older children andthe adults still preferred a lexical noun phrase in response to “What’s happeningthere?” which result that was also confirmed by Matthews et al. (2006).
The situation was somewhat different in the condition in which the discoursecue called for an answer containing a less informative expression, but theperceptual cue required a more informative expression for the listener’s benefit(specific question/“listener not looking”). In this case the perceptual cue wonover the discourse cue, leading the older children and the adults to optpredominantly for lexical NPs. However, even the 6-year-olds were significantlyless efficient than the adults at overriding the discourse bias and unambiguouslyidentified the subject referent by using a lexical NP only 60% of the time vs. 97%of the time for the adults. At all times the participants had to remember that theyhad to look at things from their interlocutor’s point of view. This wasundemanding when the participant’s and the experimenter’s perspectives coin-cided (“listener looking” conditions), but it proved to be more problematic whenthey diverged (“listener not looking” conditions). The older children respondeddifferently to the specific question according to whether the listener was lookingat the picture or not, and thereby showed some perspective-taking ability, butthey did not do so as consistently as the adults. When they succeeded they did so
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because they corrected their own egocentric interpretation to select a referentialexpression that would be more appropriate from the experimenter’s point ofview. This correction requires a nontrivial amount of effort and it appears to beconsiderably more demanding for 3- and 5-year-olds than for 6-year-olds.
The ability to correct an initial egocentric interpretation in the presence ofconflicting perceptual scenes has recently been investigated in the context of areferential communication game by Epley et al. (2004). Epley et al. recordedschool-age children’s eye movements as they participated in a perspective-takingtask. The children were instructed to follow the experimenter’s directions tomove objects around a grid that was placed between them. On the critical trialsthere were three versions of the object that the children had to move (e.g. amedium-sized toy truck, a smaller toy truck, and a considerably smaller toytruck). The one that provided the best fit to the directors’ instructions (e.g. “Movethe small truck above the glue”) was always visible to the child, but occludedfrom the director’s view. Epley et al. found that children looked significantlyfaster at the hidden object that was the best fit from their own perspective than tothe one that was the next best fit but was the only possible solution from thedirector’s point of view. By contrast, in a similar perspective-taking task Nadig& Sedivy (2002) reported that the children in their study looked faster at theobject that was also visible to the director rather than to the one that only theycould see. Crucially, however, in Nadig & Sedivy’s experiment both the hiddenand the visible objects were exactly the same, therefore an equally goodreferential fit to the linguistic cue provided by the director. In this case, as Epleyet al. observe, there was no conflict between the children’s and the director’sperspective, thus complying with the instruction was rather undemanding. Theresults of the current studies are in line with the findings of Epley et al. (2004)and Nadig & Sedivy (2002), and provide yet more support to the idea thatdifficulties are likely to arise when cues enter into conflict with one another, andthat children have to abandon their own privileged point of view to accommodateanother’s perspective. It must nevertheless be acknowledged that the current studyonly looked at a selected number of discourse and perceptual constraints that affectreferential choice. There are many more sources of information that children (andadults) need to attend to in order to establish whether an entity is part of the com-mon ground or not. Metzing & Brennan (2003), for example, have shown howsome of these cues may even be partner-specific, and how expectations change notonly as a function of prior discourse, but as a function of the collaborative way inwhich common ground is jointly established by two speakers over time.
The Role of the Number of Referents in the Scene
If dealing with the perceptual cue provided by the referent’s accessibility to thelistener taxed even the older children’s referential abilities, the perceptual cue
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made available by the number of referents posed no particular difficulties, exceptto the 3-year-olds, who again used a small proportion of lexical NPs overall, butwho nevertheless used more lexical NPs with two-referents scenes than with one-referent scenes (see Hurewitz et al. 2001, for similar findings in an elicitedproduction task). The introduction of pictures with two referents in Study 2 allowedthe question of whether children are sensitive to the need to disambiguate twoentities that are both present in the same scene. The results of one of Wittek &Tomasello’s (2005) studies showed that contrast questions such as, “Did theclown have a vacuum cleaner?” elicited responses containing a pronoun subjectand an object realized by a lexical NPs (e.g. “No, he had a broom”), or simply anobject NP (e.g. “No, a broom”). As the authors observe, the high proportion ofobject NPs produced by the 2- and the 3-year-olds in these contexts is in line withthe predictions of “preferred argument structure” (DuBois, 1987), whereby lexi-cal NPs are more likely to be objects (O) or subjects of intransitive verbs (S) thansubjects of transitive verbs (A). The specific questions of Study 2, unlike Wittek& Tomasello’s contrast questions, were not focused on the object (e.g. “What arethose people eating/reading/chopping?”), but on the whole event (e.g. “What arethose people doing?”). Also, in contrast to Wittek & Tomasello’s study, in Study2 the referents of interest were always the subjects of transitive actions (A),therefore in principle less likely to be realized by a lexical noun phrase accordingto a “preferred argument structure.” Despite this discourse constraint, it was stillexpected that the presence of two referents engaged in different actions would bean ideal set-up for disambiguation, and thus provide a strong cue to overt argu-ment realization (see Allen, 2000 for the key role of contrast in overt argumentrealization). Because the two referents in our picture were of different gender andwere each engaged in two different actions (e.g. eating and drinking), we antici-pated that the question “What are those people doing?” would call for the use oftwo gender-marked pronouns in the ”listener looking” condition. In the “listenernot looking” condition we expected lexical NPs for the purpose of unambiguousreferential identification. The results for the two-referent conditions did indeedshow that the perceptual cue provided by the number of referents played a role indetermining the choice of referential expression. Even the 3-year-old childrenused more lexical NPs in the “listener looking” condition when there were tworeferents than when there was only one, although the difference was not signifi-cant. The 6-year-olds behaved like adults with more than two-thirds of the lexicalNPs in the two-referent/“listener looking” condition, while the behavior of the 5-year-olds was unique, inasmuch as they used lexical NPs, null reference, and“one . . . and the other . . .” equally often. The use of “one . . . and the other . . .”is perfectly acceptable in a context in which the listener has access to the pic-tures, but it was not the preferred option of either the 6-year-olds or the adultswho predominantly opted for lexical NPs. These findings show that the percep-tual cue provided by the number of referents was stronger than the perceptual cue
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provided by the referent’s accessibility, and, incidentally, also stronger than thepreferred argument structure nonlexical A constraint. Following Arnold & Griffin(2007), this pattern may be explained by the need to satisfy speaker-internalprocessing needs rather than by the need to make the entity interpretable to thelistener.
In conclusion, the findings of the current studies lend support to the idea thatin the transition from preschool age to the early school years, children becomeprogressively more attuned to different types of discourse and perceptual cues inthe choice of referential expressions.
ACKNOWLEDGMENTS
This research was supported by a British Academy grant (SG 39735). I am verygrateful to the children who took part in the studies, and to the headteachers andthe teachers at the following nurseries and primary schools in Exeter, Devon:Bumble Bees Day Nursery, Chestnut Avenue Nursery School, The MariaMontessori School, Redhills Combined School.
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