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Is a dog on a leash a tamed wolf ? - Comparison of semantic relations processing in autistic and neurotypical individuals
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Charlotte Laffargue1, Philippe Gréa1; 1Université Paris Nanterre
Autism Spectrum Disorder (ASD) is often associated with difficulties in pragmatic language use, particularly in adapting speech to context, understanding implicit meaning, and managing conversational interactions. However, despite extensive research, lexical organization in autism remains poorly understood. Previous studies have yielded inconsistent findings, partly because they mainly rely on picture-naming tasks, which involve multiple cognitive processes from visual recognition to phonological production. Such tasks therefore do not directly isolate semantic organization itself. In neurotypical individuals (NT), lexical access has been described as a process of spreading activation across semantic networks (Collins & Loftus, 1975) structured through different types of semantic relations. Taxonomic relations, based on similarity between concepts, are thought to rely mainly on perceptual processing. Thematic relations, by contrast, connect concepts belonging to the same context and involve conceptual processing (Jones et al., 2011; Mirman, 2017). The present study focuses specifically on these two relations. According to the Weak Central Coherence theory (Frith, 1989; Happé & Frith, 2006), autistic individuals preferentially process local and perceptual information rather than global and conceptual information. Applied to semantic memory, this theory predicts a stronger reliance on taxonomic relations than on thematic relations in ASD. Three experimental tasks were administered. The first was a lexical decision task with semantic priming. Participants responded to target words preceded either by a semantically related or unrelated prime. Two semantic conditions were tested: taxonomic and thematic. In neurotypical individuals, semantic priming generally facilitates processing in both conditions. The hypothesis was that autistic participants would show facilitation mainly in the taxonomic condition. The second experiment was a picture-naming task with word-picture interference. In neurotypical populations, thematically related distractor words facilitate naming, whereas taxonomically related distractors produce interference effects (de Zubicaray, 2013). The third experiment was a verbal fluency task in which participants produced either category-based words (animals) or thematic-based words (holidays). Better performance was expected in the taxonomic condition for autistic participants. The study included two groups, one NT one ASD, of French-speaking adults aged 18–45, with average IQ and no formal language disorders or learning disabilities, Diagnostic reports were collected to ensure group homogeneity. Preliminary results revealed clear group differences : In the semantic priming task, NT participants showed the expected facilitation effect (24ms) in both taxonomic and thematic conditions. Autistic participants also demonstrated facilitation in the taxonomic condition, with effects comparable to those of neurotypical participants. However, in the thematic condition, they showed a marked inhibition effect (-61 ms). Similarly, neurotypical participants produced comparable numbers of words (31) in both verbal fluency conditions, whereas autistic participants generated substantially more responses in the taxonomic condition (32) as in the thematic condition (23). Analysis of the word-picture interference task is still ongoing. These results highlight a semantic organization specific to autism, whose explanation, however, cannot be reduced solely to WCC. The inhibition effect generally suggests an impairment in executive functioning, a domain that has been widely investigated in autism and is currently being explored further through the development of new experiments, particularly using double-priming paradigms.
Topic Areas: Meaning: Lexical Semantics, Disorders: Acquired