Peripheral global neglect in high vs. low autistic tendency

Abstract

In addition to its core social deficits, autism is characterized by altered visual perception, with a preference for local percept in those high in autistic tendency. Here, the balance of global vs. local percepts for the perceptually rivalrous diamond illusion was assessed between groups scoring high and low on the Autism Spectrum Quotient (AQ). The global percept of a diamond shape oscillating horizontally behind three occluders can as easily be interpreted as the local percept of four line elements, each moving vertically. Increasing the luminance contrast of the occluders with respect to background resulted in an increase of initial global percept in both groups, with no difference in sensitivity between groups. Presenting the target further into the periphery resulted in a marked increase in the percentage of global perception with visual field eccentricity. However, while the performance for centrally presented diamond targets was not different between AQ groups, the peripheral global performance of the High AQ group was significantly reduced compared with the Low AQ group. On the basis of other imaging studies, this peripheral but not foveal global perceptual neglect may indicate an abnormal interaction between striate cortex and the Lateral Occipital Complex (LOC), or to differences in the deployment of attention between the two groups.

Keywords: AQ; autism; autistic tendency; diamond illusion; global percept; local percept; magnocellular; parvocellular.

Figure 1

(A) Schematic of the diamond illusion showing the diamond shape oscillating horizontally behind three occluding stripes of the same color and luminance as the background. (B) Resultant perception is either “Local” with 4 lines moving up and down or (C). “Global” perception where the motion of the lines is grouped and they are seen as moving horizontally back and forth (redrawn from Fang et al., 2008).

Figure 2

Means and standard error of initial global percept (expressed as a percentage) as a function of occluder contrast for the Low and High AQ groups.

Figure 3

Means (with standard error) of percentage of initial global percept for Low and High AQ groups when viewing the stimulus at various eccentricities in visual field. The data for High AQ are shown with a solid red line, while those for the Low AQ group are shown as a dashed green line. Parabolic fits (gray color) to the two sets of data allow a comparison of relative eccentricities required to give equivalence of global percept between the High AQ and Low AQ groups.