Colour perception in Autism Spectrum Condition and Williams Syndrome

Abstract

Autism Spectrum Condition (ASC) and Williams syndrome (WS) are neurodevelopmental conditions associated with socio-communicative deficits. Also, present in both conditions are sensory sensitivities and reactivities. In ASC extreme sensory reactivity/sensitivities in one or more of any sensory domain have recently been recognised as new diagnostic criteria in DSM-V. Whilst in WS there are reported visuo-spatial and auditory atypicalities. There is increasing importance in identifying both the typical and atypical development of sensory processing, as well as establishing condition-specific and condition-general aspects of sensory processing. Traditionally sensory processing has been studied using a cross-sectional design using either psychophysical tasks or behavioural questionnaires. However little work has attempted to link between these different methodologies resulting in a disconnected study of sensory processing in both typical and atypical development. Colour perception is useful domain to study sensory processing because it can be characterised through psychophysical/cognitive tasks and behavioural questionnaires. Colour perception is also relatively understudied in both ASC and WS despite anecdotal reports of behaviour being influenced by colour. The present research aims to investigate colour perception in ASC and WS relative to mental age typically developing (TD) controls using the same participants across a combination of psychophysical (chromatic discrimination - chapter 3), cognitive (chapters 4 and 5, colour preference and naming), questionnaire (chapter 6) and case studies (chapter 7) methodologies to establish a rounded representation of colour perception in ASC and WS through using these mixed methodologies. The results show condition specific atypicalities across all tasks relative to TD controls. For the ASC group, there was poorer chromatic discrimination, different colour preference patterns and increased frequency of colour affected behaviours. Whilst the WS group showed less pronounced colour preference patterns and atypical colour naming. The differences in results between different measurements of colour perception and condition-specific responses between the ASC and WS suggest that sensory processing is not a homogenous concept but should be considered in relation to the measurements chosen. The results are discussed within the context of diagnostic criteria, approaches to studying sensory processing and syndrome-specificity.