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Magnocellular visual evoked potential delay with high autism spectrum quotient yields a neural mechanism for altered perception . Everyone has autistic characteristics to a greater or lesser degree , encapsulated in the Autism Spectrum Quotient , a scale that measures the degree to which an adult of normal intelligence displays traits associated with autism spectrum disorders . Recent psychophysical analyses of autism spectrum disorders point to superior local processing , and impaired or ignored global and contextual processing . The aim of this study was to test whether low- and high-scoring individuals on the Autism Spectrum Quotient differ on a measure of local and global processing , motion processing and visual pathway integrity . Fifteen low-scoring individuals and 14 high-scoring individuals derived from a normal population participated in the study . The results indicate that the initial cortical response to the magnocellular afferents is weaker at low contrast in the high autistic tendency group and that a second-order response , reflecting magnocellular activity , demonstrated a delay for high versus low scorers when the parvocellular pathway was also active in response to a high contrast stimulus . High-scoring individuals also demonstrated difficulty in identifying the global components of locally salient hierarchical Navon figures . Furthermore , cross-validated discriminant analysis , using four physiologically and three psychophysically derived parameters , correctly classified 83 % of individuals who scored either high or low on the Autism Spectrum Quotient . These findings in the group scoring high on the Autism Spectrum Quotient indicate that a delay in primary visual/prestriate cortical processing of magnocellular input diminishes the advantage of its early arrival to primary visual cortex . This appears to be associated with impaired global visual perception , predicting with high accuracy behavioural tendencies associated with autism spectrum disorders . It has been proposed that perceptual impairment in autism may be attributed to a dysfunction of horizontal connections within early visual areas , presumably parvocellular in nature . However , the timing of such form processing aberrations is much later than the timing of abnormal magnocellular visual processing measured directly here . Thus it is proposed that a magnocellular processing delay decreases the ability of autistic individuals to benefit perceptually from feedback normally associated with the magnocellular advantage .
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Intervention_Other
Magnocellular visual
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Intervention_Other
local and global processing
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Intervention_Other
motion processing
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Intervention_Other
visual pathway integrity
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Outcome_Physical
Autism Spectrum Quotient
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Outcome_Physical
local and global processing
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Outcome_Physical
cortical response
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Outcome_Other
a delay
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Outcome_Other
identifying the global components
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Outcome_Other
impaired global visual perception
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Outcome_Physical
behavioural tendencies
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Participant_Condition
high autism spectrum quotient
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Participant_Condition
adult of normal intelligence