Perceptual expectancy is revealed by pupillometry and correlates with autistic traits

Abstract

Priming refers to increased performance (usually measured by reaction times) on repetition of a perceptual feature. In Maljkovic and Nakayama’s (1994) paradigm, three pseudo-diamond shapes are displayed each trial, two of one color and one of another, and participants identify rapidly the shape of the odd-colored (target) diamond. When target colors repeat, reaction times decrease, consistent with perceptual expectation for that target color. We replicated this study while monitoring pupil size, with 27 neurotypical participants for whom we had measured Autism-Spectrum Quotient (AQ). For participants with low AQ, pupil diameter increased more on trials where the target color swapped than when it repeated, consistent with a reaction to violated perceptual expectancy. The dependence of pupil dilation on previous trial color correlated strongly with AQ scores. This result is consistent with the suggestion that integration of prior information may be sub-optimal in individuals with high autistic traits (Pellicano and Burr, Trends Cogn Sci, 2012). However, neither the average pupil response nor the difference in reaction times were predicted by AQ. Overall the results show that pupil response can provide useful non-invasive measures of priming effects related to perceptual expectancy, and go on to show how this objective measure can vary with personality traits such as AQ.

Acknowledgement: ERC Grant Pupiltraits