Evidence of global weakness in autism spectrum disorder

Background: In Frith’s original description of weak central coherence, the assets and deficits seen in autism were thought to stem from a single cognitive characteristic.  This implied that reduced global integration of information results in enhanced local processing.  More recent accounts of this theory emphasize the role of superior local perception with independent, and possibly intact, global integration skills.  However it is questionable whether the measurement of local and global processing is indeed independent, with most paradigms used to test weak coherence often placing local and global processing in direct trade-off.  Typically it is not possible to determine whether patterns of performance in autism are a consequence of reduced global processing, increased local processing, or both. 

Objectives: We aimed to design measures that tap global integration unconfounded with local processing bias.

Methods: Two novel measures of visual integration were designed: (1) a modified Fragmented Picture-Completion task which required participants to identify a picture from fragments and (2) an (Im)possible Figures task which required participants to judge whether three-dimensional figures could be geometrically possible.  Performance on both measures were compared between 30 males with ASD and 30 controls, matched in age and IQ, as well as within a large typically developing population (N = 201). 

Results: Poor integrative processing was found in the ASD group compared to 30 controls: participants with ASD required more completed fragments in order to identify an image and had lower sensitivity to impossibility.  A relationship between sensitivity in discriminating possible and impossible figures and the incremental amount of information required to detect fragmented pictures was found in the typically developing sample (N = 201, r = -.20 to -.30 which held after controlling for IQ and age). However no such relationship was found in the ASD and matched control groups.

Conclusions: Evidence of reduced global processing was found in individuals with ASD compared to matched controls, suggesting Frith’s original notion of weak coherence as both reduced global integration and increased local perception is worth revisiting.  However the role of perceptual integration versus cognitive flexibility for the theory of weak coherence also requires some consideration.