Perception of shapes targeting local and global processes in autism spectrum disorders.
BACKGROUND
Several researchers have found evidence for impaired global processing in the dorsal visual stream in individuals with autism spectrum disorders (ASDs). However, support for a similar pattern of visual processing in the ventral visual stream is less consistent. Critical to resolving the inconsistency is the assessment of local and global form processing ability.


METHODS
Within the visual domain, radial frequency (RF) patterns - shapes formed by sinusoidally varying the radius of a circle to add 'bumps' of a certain number to a circle - can be used to examine local and global form perception. Typically developing children and children with an ASD discriminated between circles and RF patterns that are processed either locally (RF24) or globally (RF3).


RESULTS
Children with an ASD required greater shape deformation to identify RF3 shapes compared to typically developing children, consistent with difficulty in global processing in the ventral stream. No group difference was observed for RF24 shapes, suggesting intact local ventral-stream processing.


CONCLUSIONS
These outcomes support the position that a deficit in global visual processing is present in ASDs, consistent with the notion of Weak Central Coherence.
Grinter
Emma J
EJ
School of Psychology, University of Western Australia. emmagrinter@graduate.uwa.edu.au
Maybery
Murray T
MT
Pellicano
Elizabeth
E
Badcock
Johanna C
JC
Badcock
David R
DR
D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002657:Child Development; D002659:Child Development Disorders, Pervasive / Q000503:physiopathology*; D001330:Electronic Data Processing; D005260:Female; D006801:Humans; D008297:Male; D014796:Visual Perception