Local-global processing and cognitive style in autism spectrum disorders and typical development
This thesis was motivated by the hypothesis that a continuum of cognitive style may
exist in the general population, from strong to weak coherence. On this conceptualisation,
individuals with autism spectrum disorder (ASD) are proposed to lie at the extreme weak
coherence or detail-focused end of the continuum. A battery of 14 coherence measures
was administered to over 200 typically developing (Tn) individuals, 31 individuals with
ASD, and 31 age- and IQ-matched control participants. The pervasiveness of central
coherence was tested across visuo-spatial and auditory/verbal domains, and high- and lowlevels
Age and IQ were typically related to task performance in the TD group, but a large
proportion of variance remained unexplained and may reflect cognitive style. Low-level
tasks were associated within and across visual and auditory domains, suggesting some
consistency in individual differences. High-level tasks did not show such consistency,
suggesting that executive/strategic processes may have greater effect on task performance
than local-global processing style. Males showed greater detail-focus and stronger
developmental effects (more global with age) than females on several measures.
Weak coherence was demonstrated in ASD by local processing bias and lack of global
bias. Local and good global processing appeared to be more in trade-off in the ASD group
than in TD and control groups. Good local processing related to IQ in TD and controls,
but less so in ASD suggesting local bias is more automatic to individuals with ASD.
Subgroups were determined on the basis of performance across the battery, according
to whether local or global processing was dominant, or whether an individual adapted well
or poorly to the demands of the task. A consistent local processing style was more
common in the ASD group than in the control group, but was not universal The implications of these findings for weak central coherence theory of ASD are discussed.