A Specific Autistic Trait that Modulates Visuospatial Illusion Susceptibility

Abstract

Although several accounts of autism have predicted that the disorder should be associated with a decreased susceptibility to visual illusions, previous experimental results have been mixed. This study examined whether a link between autism and illusion susceptibility can be more convincingly demonstrated by assessing the relationships between susceptibility and the extent to which several individual autistic traits are exhibited as a continuum in a population of college students. A significant relationship was observed between the systemizing trait and susceptibility to a subset of the tested illusions (the rod-and-frame, Roelofs, Ponzo and Poggendorff illusions). These results provide support for the idea that autism involves an imbalance between the processing of local and global cues, more heavily weighted toward local features than in the typically developed individual.

Susceptibility to Optical Illusions Varies as a Function of the Autism-Spectrum Quotient but not in Ways Predicted by Local–Global Biases

“…We know that eye movements have a strong influence on susceptibility to the Müller-Lyer illusion (e.g., de Grave & Bruno, 2010;van Zoest & Hunt, 2011) and that people with and without ASD differ in the way they scan visual scenes (Pelphrey et al, 2002). It then follows that perhaps the effects on the Müller-Lyer illusion observed by Chouinard et al (2013) Walter et al (2009) argued that greater levels of systemising meant a greater focus on details, which in turn reduced abilities in global integration and levels of susceptibility to some of their illusions. However, we are skeptical about this interpretation for two reasons.…”

“…The second is that the illusion tasks in the Walter et al (2009) study varied considerably in a number of extraneous demands. For example, Walter et al (2009) …”

“…Specifically, Walter et al (2009) showed that susceptibility to the rod-and-frame, Roelofs, Ponzo, and Poggendorf illusions but not to the Induced motion, Zöllner, Ebbinghaus, and Müller-Lyer illusion diminished with autistic traits while Chouinard et al (2013) showed that susceptibility to the Müller-Lyer but not to the Ebbinghaus and Ponzo illusions diminished with autistic traits. The take home message from both studies is that susceptibility to only a subset of illusions correlated with autistic traits and that illusion susceptibility does not rely on a singular cognitive construct but is rather mediated by different mechanisms of global processing, some of which may or may not be affected by autistic characteristics.…”

“…The likely presence of a number of confounding factors in earlier work might explain these inconsistencies (Chouinard, Noulty, Sperandio, & Landry, 2013;Walter, Dassonville, & Bochsler, 2009). Attention, preservative behaviours, anxiety, and understanding task instructions are difficult to control and may not have been appropriately matched in a number of earlier studies of optical illusions in ASD.…”

“…Two earlier investigations examined relationships between autistic traits and susceptibility to optical illusions in typical populations (Chouinard et al, 2013;Walter et al, 2009). Specifically, Walter et al (2009) showed that susceptibility to the rod-and-frame, Roelofs, Ponzo, and Poggendorf illusions but not to the Induced motion, Zöllner, Ebbinghaus, and Müller-Lyer illusion diminished with autistic traits while Chouinard et al (2013) showed that susceptibility to the Müller-Lyer but not to the Ebbinghaus and Ponzo illusions diminished with autistic traits.…”