Aparna Nadig

Evidence of Perspective-Taking Constraints in Children's On-Line Reference Resolution

Young childrens communication has often been characterized as egocentric. Some researchers claim that the processing of language involves an initial stage that relies on egocentric heuristics, even in adults. Such an account, combined with general developmental difficulties with late-stage processes, could provide an explanation for much of childrens egocentric communication. However, the experimental data reported in this article do not support such an account: In an elicited-production task, 5- to 6-year-old children were found to be sensitive to their partners perspective. Moreover, in an on-line comprehension task, they showed sensitivity to common-ground information from the initial stages of language processing. We propose that mutual knowledge is not distinct from other knowledge relevant for language processing, and exerts early effects on processing in proportion to its salience and reliability.

What Do Children with Autism Attend to during Imitation Tasks

Individuals with autism show a complex profile of differences in imitative ability, including a general deficit in precision of imitating anothers actions and special difficulty in imitating nonmeaningful gestures relative to meaningful actions on objects. Given that they also show atypical patterns of visual attention when observing social stimuli, we investigated whether possible differences in visual attention when observing an action to be imitated may contribute to imitative difficulties in autism in both nonmeaningful gestures and meaningful actions on objects. Results indicated that (a) a group of 18 high-functioning 8- to 15-year-olds with autistic disorder, in comparison with a matched group of 13 typically developing children, showed similar patterns of visual attention to the demonstrators action but decreased attention to his face when observing a model to be imitated; (b) nonmeaningful gestures and meaningful actions on objects triggered distinct visual attention patterns that did not differ between groups; (c) the autism group demonstrated reduced imitative precision for both types of imitation; and (d) duration of visual attention to the demonstrators action was related to imitation precision for nonmeaningful gestures in the autism group.

Acoustic and Perceptual Measurement of Expressive Prosody in High-Functioning Autism: Increased Pitch Range and What it Means to Listeners

Are there consistent markers of atypical prosody in speakers with high functioning autism (HFA) compared to typically-developing speakers? We examined: (1) acoustic measurements of pitch range, mean pitch and speech rate in conversation, (2) perceptual ratings of conversation for these features and overall prosody, and (3) acoustic measurements of speech from a structured task. Increased pitch range was found in speakers with HFA during both conversation and structured communication. In global ratings listeners rated speakers with HFA as having atypical prosody. Although the HFA group demonstrated increased acoustic pitch range, listeners did not rate speakers with HFA as having increased pitch variation. We suggest that the quality of pitch variation used by speakers with HFA was non-conventional and thus not registered as such by listeners.

Adaptation of object descriptions to a partner under increasing communicative demands: a comparison of children with and without autism

This study compared the object descriptions of school‐age children with high‐functioning autism (HFA) with those of a matched group of typically developing children. Descriptions were elicited in a referential communication task where shared information was manipulated, and in a guessing game where clues had to be provided about the identity of an object that was hidden from the addressee. Across these tasks, increasingly complex levels of audience design were assessed: (1) the ability to give adequate descriptions from ones own perspective, (2) the ability to adjust descriptions to an addressees perspective when this differs from ones own, and (3) the ability to provide indirect yet identifying descriptions in a situation where explicit labeling is inappropriate. Results showed that there were group differences in all three cases, with the HFA group giving less efficient descriptions with respect to the relevant context than the comparison group. More revealing was the identification of distinct adaptation profiles among the HFA participants: those who had difficulty with all three levels, those who displayed Level 1 audience design but poor Level 2 and Level 3 design, and those demonstrated all three levels of audience design, like the majority of the comparison group. Higher structural language ability, rather than symptom severity or social skills, differentiated those HFA participants with typical adaptation profiles from those who displayed deficient audience design, consistent with previous reports of language use in autism.

Children's referential understanding of novel words and parent labeling behaviors: similarities across children with and without autism spectrum disorders *

This study examined two facets of the use of social cues for early word learning in parent-child dyads, where children had an Autism Spectrum Disorder (ASD) or were typically developing. In Experiment 1, we investigated word learning and generalization by children with ASD (age range: 3;01-6;02) and typically developing children (age range: 1;02-4;09) who were matched on language ability. In Experiment 2, we examined verbal and non-verbal parental labeling behaviors. First, we found that both groups were similarly able to learn a novel label using social cues alone, and to generalize this label to other representations of the object. Children who utilized social cues for word learning had higher language levels. Second, we found that parental cues used to introduce object labels were strikingly similar across groups. Moreover, parents in both groups adapted labeling behavior to their childs language level, though this surfaced in different ways across groups.

Learning Language in Autism: Maternal Linguistic Input Contributes to Later Vocabulary

It is well established that children with typical development (TYP) exposed to more maternal linguistic input develop larger vocabularies. We know relatively little about the linguistic environment available to children with autism spectrum disorders (ASD), and whether input contributes to their later vocabulary. Children with ASD or TYP and their mothers from English and French‐speaking families engaged in a 10 min free‐play interaction. To compare input, children were matched on language ability, sex, and maternal education (ASD n = 20, TYP n = 20). Input was transcribed, and the number of word tokens and types, lexical diversity (D), mean length of utterances (MLU), and number of utterances were calculated. We then examined the relationship between input and childrens spoken vocabulary 6 months later in a larger sample (ASD: n = 19, 50–85 months; TYP: n = 44, 25–58 months). No significant group differences were found on the five input features. A hierarchical multiple regression model demonstrated input MLU significantly and positively contributed to spoken vocabulary 6 months later in both groups, over and above initial language levels. No significant difference was found between groups in the slope between input MLU and later vocabulary. Our findings reveal children with ASD and TYP of similar language levels are exposed to similar maternal linguistic environments regarding number of word tokens and types, D, MLU, and number of utterances. Importantly, linguistic input accounted for later vocabulary growth in children with ASD. Autism Res 2015, 8: 214–223.

Reduced sensitivity to context in language comprehension: A characteristic of Autism Spectrum Disorders or of poor structural language ability?

We present two experiments examining the universality and uniqueness of reduced context sensitivity in language processing in Autism Spectrum Disorders (ASD), as proposed by the Weak Central Coherence account (Happé & Frith, 2006, Journal of Autism and Developmental Disorders, 36(1), 25). That is, do all children with ASD exhibit decreased context sensitivity, and is this characteristic specific to ASD versus other neurodevelopmental conditions? Experiment 1, conducted in English, was a comparison of children with ASD with normal language and their typically-developing peers on a picture selection task where interpretation of sentential context was required to identify homonyms. Contrary to the predictions of Weak Central Coherence, the ASD-normal language group exhibited no difficulty on this task. Experiment 2, conducted in German, compared children with ASD with variable language abilities, typically-developing children, and a second control group of children with Language Impairment (LI) on a sentence completion task where a context sentence had to be considered to produce the continuation of an ambiguous sentence fragment. Both ASD-variable language and LI groups exhibited reduced context sensitivity and did not differ from each other. Finally, to directly test which factors contribute to reduced context sensitivity, we conducted a regression analysis for each experiment, entering nonverbal IQ, structural language ability, and autism diagnosis as predictors. For both experiments structural language ability emerged as the only significant predictor. These convergent findings demonstrate that reduced sensitivity to context in language processing is linked to low structural language rather than ASD diagnosis.

Global Similarities and Multifaceted Differences in the Production of Partner-Specific Referential Pacts by Adults with Autism Spectrum Disorders

Over repeated reference conversational partners tend to converge on preferred terms or referential pacts. Autism spectrum disorders (ASD) are characterized by pragmatic difficulties that are best captured by less structured tasks. To this end we tested adults with ASD who did not have language or intellectual impairments, and neurotypical comparison participants in a referential communication task. Participants were directors, describing unlexicalized, complex novel stimuli over repeated rounds of interaction. Group comparisons with respect to referential efficiency showed that directors with ASD demonstrated typical lexical entrainment: they became faster over repeated rounds and used shortened referential forms. ASD and neurotypical groups did not differ with respect to the number of descriptors they provided or the number of exchanges needed for matchers to identify figures. Despite these similarities the ASD group was slightly slower overall. We examined partner-specific effects by manipulating the common ground shared with the matcher. As expected, neurotypical directors maintained referential precedents when speaking to the same matcher but not with a new matcher. Directors with ASD were qualitatively similar but displayed a less pronounced distinction between matchers. However, significant differences and different patterns of reference emerged over time; neurotypical directors incorporated the new matchers contributions into descriptions, whereas directors with ASD were less likely to do so.

Acoustic marking of prominence: how do preadolescent speakers with and without high-functioning autism mark contrast in an interactive task?

The acoustic correlates of discourse prominence have garnered much interest in recent adult psycholinguistics work, and the relative contributions of amplitude, duration and pitch to prominence have also been explored in research with young children. In this study, we bridge these two age groups by examining whether specific acoustic features are related to the discourse function of marking contrastive stress by preadolescent speakers, via speech obtained in a referential communication task that presented situations of explicit referential contrast. In addition, we broach the question of listener-oriented versus speaker-internal factors in the production of contrastive stress by examining both speakers who are developing typically and those with high-functioning autism (HFA). Diverging from conventional expectations and early reports, we found that speakers with HFA, like their typically developing peers (TYP), appropriately marked prominence in the expected location, on the pre-nominal adjective, in instructions such as “Pick up the BIG cup”. With respect to the use of specific acoustic features, both groups of speakers employed amplitude and duration to mark the contrastive element, whereas pitch was not produced selectively to mark contrast by either group. However, the groups also differed in their relative reliance on acoustic features, with HFA speakers relying less consistently on amplitude than TYP speakers, and TYP speakers relying less consistently on duration than HFA speakers. In summary, the production of contrastive stress was found to be globally similar across groups, with fine-grained differences in the acoustic features employed to do so. These findings are discussed within a developmental framework of the production of acoustic features for marking discourse prominence, and with respect to the variations among speakers with autism spectrum disorders that may lead to appropriate production of contrastive stress.

Automatic forced alignment on child speech: Directions for improvement

Phonetic analysis is labor intensive, limiting the amount of data that can be considered. Recently, automated techniques (e.g., forced alignment based on Automatic Speech Recognition - ASR) have emerged allowing for much larger-scale analyses. For adult speech, forced alignment can be accurate even when the phonetic transcription is automatically generated, allowing for large-scale phonetic studies. However, such analyses remain difficult for childrens speech, where ASR methods perform more poorly. The present study used a trainable forced aligner that performs well on adult speech to examine the effect of four factors on alignment accuracy of child speech: (1) Corpus - elicited speech (multiple children) versus spontaneous speech (single child); (2) Pronunciation dictionary - standard adult versus customized; (3) Training data - adult lab speech, corpus-specific child speech, all child speech, or a combination of child and adult speech; (4) Segment type - voiceless stops, voiceless sibilants, and vowels...