The pupillary light response as a physiological index of aphantasia, sensory and phenomenological imagery strength

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Abstract

The pupillary light response is an important automatic physiological response which optimises light reaching the retina. Recent work has shown that the pupil also adjusts in response to illusory brightness and a range of cognitive functions, however, it remains unclear what exactly drives these endogenous changes. Here we show that the imagery pupillary light response correlates with objective measures of sensory imagery strength. Further, the trial-by-trial phenomenological vividness of visual imagery is tracked by the imagery pupillary light response. We also demonstrated that a group of individuals without visual imagery (aphantasia) do not show any significant evidence of an imagery pupillary light response, however they do show perceptual pupil light responses and pupil dilation with larger cognitive load. Our results provide evidence that the pupillary light response indexes the sensory strength of visual imagery and this work also provides the first physiological validation of aphantasia.

Data availability

Figure 1 - Source Data 1& 2, Figure 2 - Source Data 3, and Figure 3 - Source Data 4 contain the numerical data used to generate the figures.

Article and author information

Author details

Lachlan Kay

School of Psychology, University of New South Wales, Sydney, Australia

Competing interests
The authors declare that no competing interests exist.
Rebecca Keogh

School of Psychological Sciences, Macquarie University, Sydney, Australia

For correspondence
rebeccalkeogh@gmail.com

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-4814-433X
Thomas Andrillon

Institut du Cerveau - Paris Brain Institute, Sorbonne Université, Paris, France

Competing interests
The authors declare that no competing interests exist.
Joel Pearson

School of Psychology, University of New South Wales, Sydney, Australia

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-3704-5037

Funding

National Health and Medical Research Council (APP1024800)

Joel Pearson

National Health and Medical Research Council (APP1046198)

Joel Pearson

National Health and Medical Research Council (APP1085404)

Joel Pearson

National Health and Medical Research Council (APP1049596)

Joel Pearson

Australian Research Council (DP140101560)

Joel Pearson

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: Informed written consent was obtained from all participants to participate in the experiment and to publish their anonymised data in a journal article. Both experiments were approved by the UNSW Human Research Ethics Advisory Panel (HREAP-C 3182).

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.