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Access to lexical meaning in children with Autism Spectrum Disorder: Reconsidering the role of socio-pragmatic understanding

par Ostashchenko, Ekaterina
Président du jury Luffin, Xavier
Promoteur Kissine, Mikhail
Publication Non publié, 2018-10-10

Thèse de doctorat

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Résumé :

Let’s imagine a typical word-learning scenario. A toddler sits in her highchair in the kitchen and waits for her lunch. Her mother says: “Use a spoon to eat your meal”. Several objects are placed in front of the child. She can see a dish with her lunch, a spoon, a cup, a sugar bowl, a milk jar, her mother’s plate and a second cup. All these objects, present in the visual array, must be identified by the toddler; she must also parse the auditory stream into segments and determine which words are familiar and which ones are potentially new. If the child does not know the word “spoon”, she will need to use the event of naming of this referent by her mother to adjust her attention to the relevant referent. She also needs to update her representation of this word upon hearing it in different contexts with different speakers and, perhaps, different types of spoons. Efficient attention allocation in this word-learning situation will clearly contribute to the success of mapping; the degree of encoding of the word-form and of its meaning will certainly influence whether this word enters the child’s vocabulary.The complexity of such a typical scenario seems very challenging for a toddler whose cognitive resources are still far from being fully mature. Unsurprisingly, several accounts of how toddlers manage to solve this task are currently on the market. The problem of ambiguity associated with meaning-to-referent mapping (several objects co-presented in the visual scene) and with word form-to-meaning mapping (the correct word is to be singled out among phonological competitors) might be even more challenging for children who present an atypical developmental trajectory.Children with Autism Spectrum Disorder and toddlers at risk for the disorder were found to acquire their vocabularies at a slower rate than their typically developing peers. In the contemporary literature, this delay in lexical knowledge acquisition is associated with poor socio-pragmatic understanding that presumably limits children’s capacity to establish referents for words in social contexts. Since impaired understanding of social interaction is a core characteristic of the cognitive profile of individuals with ASD, such an explanation of the delay in language development seems very plausible. However, several other theoretical accounts hold that in typical development socio-pragmatic skills emerge, bottom-up, through more domain-general processing of interactional experiences. In line with the latter views, it can be hypothesized that delays in lexical acquisition in ASD are not directly linked to poor socio-pragmatic understanding but are caused by low-level deficits and atypical attention allocation during word learning.Research programs on lexical learning and processing in ASD thus face the existence of different, contradictory theories of first language acquisition in typical development. Deciding a priori to build one’s experimental study against this or that theoretical background carries the risk of a limited interpretation of experimental results. A more promising way to deal with the variety of available theories of language acquisition is rather to directly confront the existing paradigms and to plan the study design in accordance. This is the approach that I privilege here. In the studies presented within this thesis, I question how social cues are used to resolve ambiguity in meaning during word-learning tasks (chapter 1) and during referential processing in typically developing children (chapter 2) and in children with ASD (chapter 3). Not only do I attempt to compare the use of social cues in word-learning and of perspectival information in referential processing in children with and without ASD, but I also try to link these results with two opposing theoretical views: the one that postulates early reliance on socio-pragmatic understanding and the other that conceives of word-learning as not being necessarily grounded in social understanding. In Chapter 1, I present evidence that children with ASD, children with SLI and typically developing children learn novel words in a flexible way by selectively attending to mappings offered by previously accurate speakers. However, I also show that such learning is likely to be supported by a surface trait attribution mechanism, rather than by genuine socio-pragmatic understanding: children in both clinical groups fail to learn selectively, when learning requires genuinely building a model of the speakers’ epistemic states. Chapters 2 and 3 are devoted to referential communication. I adopt several analytical and methodological modifications to existing methods, which allows me to compare two different aspects of partner-dependent processing of referential precedents. Typically developing children can be expected to recognize precedents previously established with the same partner faster, because of an automatic priming mechanism. However, potential faster processing of broken precedents with a new partner could not be explained by a low-level memory mechanism and would strongly suggest that lexical processing is influenced by expectations about the child’s partner perspective. I present evidence that children with and without ASD do not spontaneously rely on common ground during referential processing and that partner-specific effects in processing are associated with low-level priming. In chapter 3, I report evidence of impaired ability to switch between different conceptual perspectives in children with ASD, which may lead to maladaptive behavior in communication. In the last chapter of this thesis, I explore how word form-to-meaning ambiguity is resolved in children with ASD and whether these children exhibit difficulty in correctly mapping similar-sounding novel words. The results of this study suggest that lexical activation in children with ASD may be impaired and they display deficits in suppressing phonological competitors. Taken together, the results presented in this doctoral dissertation suggest that delays in word acquisition in ASD are likely to be driven by deficits in domain-general cognitive development. Even though impaired socio-cognitive understanding may lead to difficulties in discourse and pragmatics in older children, delayed access to lexical meaning in young children with ASD is likely to be associated with disruptions in domain-general mechanisms of perception, attention and memory.