Exploring Concurrent Interrelations Between Symbolic and Social-Cognitive Domains in Autistic and Neurotypical Children

Carter, Cheriece and Hartley, Calum and Lewis, Charlie (2024) Exploring Concurrent Interrelations Between Symbolic and Social-Cognitive Domains in Autistic and Neurotypical Children. PhD thesis, Lancaster University.

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Abstract

To advance understanding of relationships between symbolic communication systems, this thesis examines concurrent predictive associations between social-cognitive skills, picture comprehension and production, and symbolic play in autistic and neurotypical children. As social communication and language abilities are intimately related in early neurotypical development, and may provide a vital scaffold for play and pictorial domains, delays and differences in these scaffolding bases – such as those commonly observed in autism – could have critical downstream consequences for non-linguistic symbolic domains. Studies 1 and 2 investigate predictive relationships between symbolic domains (social communication, play, and pictures) and other individual differences (e.g. language abilities, non-verbal intelligence, and fine motor skills) in neurotypical 2–5-year-olds (Study 1) and language-delayed autistic 4–11-year-olds (Study 2). Study 1 reports bidirectional interrelationships between pictorial, play, and social communication domains, suggesting that these modules of symbolic development may be underpinned by shared factors in neurotypical children. In Study 2, pictorial and symbolic play abilities were bidirectionally related, and both these domains were predicted by social communication and/or social scaffolding, although proficiency in play and pictorial domains did not appear to reciprocally contribute to social communication abilities. Study 3 explores whether there are differences in the presence, direction, and magnitude of predictive relationships between symbolic domains in autistic and neurotypical children matched on language comprehension (M age equivalent = autistic: 44.11 months; neurotypical: 44.30 months). Although social communication skills predicted play and pictorial abilities in neurotypical children, this was not observed in autistic children. Evidence for possible relationships between play and pictorial domains was identified in neurotypical children, but not autistic children. These findings suggest that non-linguistic 17 symbol systems (e.g. play and pictures) in neurotypical children are interdependent and mediated by social-cognitive abilities. However, in autistic children, symbolic domains may be relatively independent and the lack of relationships with social communication skills potentially implicates a different route to acquiring symbol systems. Study 4 examines how autistic children and language-matched neurotypical children (M age equivalent = autistic: 43.60 months; neurotypical: 44.75 months) learn novel vocabulary from pictures and how this is influenced by iconicity (i.e. the extent to which a symbol resembles its intended referent). Autistic children achieved significantly greater retention accuracy when learning object names from highly iconic colour photographs compared to less iconic black-and-white cartoons and, surprisingly, responded more accurately than neurotypical children when learning from photographs. These findings suggest that learning words from pictures may be more cognitively challenging for neurotypical children than learning words from objects, and that autistic children benefit from greater iconicity when learning words from pictures. Overall, this thesis demonstrates differences in the relatedness of symbolic domains between populations. Play and pictures were consistently interrelated and supported by social communicative abilities in both neurotypical and autistic children. While bidirectional relationships between social communication, play, and pictures were observed in neurotypical children, this was not the case for autism. Direct population comparisons involving language-matched participants drawn from both populations suggest that understanding of non-linguistic symbols is interdependent and mediated by social-cognitive abilities in neurotypical children. In contrast, symbolic domains appeared to be relatively more independent and less consistently scaffolded by social skills in autism. At an applied level, these results have important implications for the design/delivery of early education practices and clinical interventions, and provide a data-grounded rationale for using colour photographs when administering picture-based interventions for autistic individuals.