Pupillometry reveals perceptual differences that are tightly linked to autistic traits in typical adults

Marco Turi,Paola Binda,David Charles Burr

doi:10.7554/elife.32399

Abstract

The pupil is primarily regulated by prevailing light levels but is also modulated by perceptual and attentional factors. We measured pupil-size in typical adult humans viewing a bistable-rotating cylinder, constructed so the luminance of the front surface changes with perceived direction of rotation. In some participants, pupil diameter oscillated in phase with the ambiguous perception, more dilated when the black surface was in front. Importantly, the magnitude of oscillation predicts autistic traits of participants, assessed by the Autism-Spectrum Quotient AQ. Further experiments suggest that these results are driven by differences in perceptual styles: high AQ participants focus on the front surface of the rotating cylinder, while those with low AQ distribute attention to both surfaces in a more global, holistic style. This is the first evidence that pupillometry reliably tracks inter-individual differences in perceptual styles; it does so quickly and objectively, without interfering with spontaneous perceptual strategies.

Highlights

A visual scene can be perceived at various hierarchical levels of structure, from the most local elements to the global organization
We measured pupil size while subjects viewed a structure-from-motion stimulus perceived as a cylinder rotating in 3D with bistable direction
The magnitude of the modulation was tightly correlated with the Autistic Quotient scores, consistent with the view that stronger autistic traits accompany a preference for focusing on local detail, as opposed to globally attending the whole stimulus configuration

Summary

Introduction

A visual scene can be perceived at various hierarchical levels of structure, from the most local elements to the global organization. A dense patch of trees is perceived as a forest at a global level, while a progressively more local analysis reveals the individual trees, their leaves, bark, etc. Different authors have developed relatively simple perceptual tasks that have become established indexes of the preference for local or global: the block design task (Kohs, 1920; Wechsler, 1955), the Rod-and-Frame Test (Witkin and Asch, 1948); the Embedded Figures Test (EFT: 5); and Navon’s hierarchical letters (Navon, 1977). There is increasing interest in determining whether differences in the preference for local or global styles are associated with autistic traits in the typical population, supporting the dimensional view of autistic disorders, where people with and

Methods

Results

Conclusion