Increasing pupil size is associated with improved detection performance in the periphery

Lisa Valentina Eberhardt,Christoph Strauch,Tim Samuel Hartmann,Anke Huckauf

doi:10.3758/s13414-021-02388-w

Lisa Valentina Eberhardt, Christoph Strauch + Show 2 more

Open Access

https://doi.org/10.3758/s13414-021-02388-w

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Abstract

Visible light enters our body via the pupil. By changing its size, the pupil shapes visual input. Small apertures increase the resolution of high spatial frequencies, thus allowing discrimination of fine details. Large apertures, in contrast, provide a better signal-to-noise ratio, because more light can enter the eye. This should lead to better detection performance of peripheral stimuli. Experiment 1 shows that the effect can reliably be demonstrated even in a less controlled online setting. In Experiment 2, pupil size was measured in a laboratory using an eye tracker. The findings replicate findings showing that large pupils provide an advantage for peripheral detection of faint stimuli. Moreover, not only pupil size during information intake in the current trial n, but also its interaction with pupil size preceding information intake, i.e., in trial n-1, predicted performance. This suggests that in addition to absolute pupil size, the extent of pupillary change provides a mechanism to modulate perceptual functions. The results are discussed in terms of low-level sensory as well as higher-level arousal-driven changes in stimulus processing.

Highlights

The light reflected by an object enters our body via an aperture in our eyes, the pupil
We investigate the impact of pupil size, manipulated by brightness of a taskirrelevant background, on peripheral detection performance
To investigate the effect of stimulus intensity, background brightness during and background brightness preceding information intake on peripheral detection performance on a trial basis, we conducted a logistic mixed-model analysis, which was nested within participants

Summary

Introduction

The light reflected by an object enters our body via an aperture in our eyes, the pupil. Distributed primarily in the peripheral parts of the retina, perceptual effects of dynamically adapting pupils should be observable especially in peripheral vision Taken together, it is still unclear whether alterations in task performance are to be attributed to fluctuations in central activation (as indicated by pupil size; e.g., Van Kempen et al, 2019; Unsworth & Robison, 2016) or to changes in sensory information since pupil size changes alter retinal illumination, resulting in an altered visual image. There is some evidence that large pupils improve visual sensitivity, measured, for example, by detection performance Since this seems to be especially related to dark adaptation by the rods in the retina (Woodhouse & Campbell, 1975), this should be observable especially in peripheral vision (i.e., Mathôt & Ivanov, 2019; Weiler, 1910). To determine the effects of pupil dynamics, we modeled the data to include pupil size during information intake and the pupil size during the previous trial into the analysis

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