Anticipatory Baseline Pupil Diameter Is Sensitive to Differences in Hearing Thresholds.

Nicolai D Ayasse,Arthur Wingfield

doi:10.3389/fpsyg.2019.02947

Abstract

Task-evoked changes in pupil dilation have long been used as a physiological index of cognitive effort. Unlike this response, that is measured during or after an experimental trial, the baseline pupil dilation (BPD) is a measure taken prior to an experimental trial. As such, it is considered to reflect an individual’s arousal level in anticipation of an experimental trial. We report data for 68 participants, ages 18 to 89, whose hearing acuity ranged from normal hearing to a moderate hearing loss, tested over a series 160 trials on an auditory sentence comprehension task. Results showed that BPDs progressively declined over the course of the experimental trials, with participants with poorer pure tone detection thresholds showing a steeper rate of decline than those with better thresholds. Data showed this slope difference to be due to participants with poorer hearing having larger BPDs than those with better hearing at the start of the experiment, but with their BPDs approaching that of the better hearing participants by the end of the 160 trials. A finding of increasing response accuracy over trials was seen as inconsistent with a fatigue or reduced task engagement account of the diminishing BPDs. Rather, the present results imply BPD as reflecting a heightened arousal level in poorer-hearing participants in anticipation of a task that demands accurate speech perception, a concern that dissipates over trials with task success. These data taken with others suggest that the baseline pupillary response may not reflect a single construct.

Highlights

The primary biological function of flexibility in the size of the pupil of the eye is to modulate the amount of light reaching the retina (Wang et al, 2016), pupil size responds to a range of psychological states (e.g., Kim et al, 2000; Kinner et al, 2017)
In the domain of speech comprehension, the relationship between cognitive effort and pupil dilation appears in the form of an increase in pupil diameter while listeners are Hearing and Baseline Pupil Size attending to speech degraded by noise or reduced hearing acuity (e.g., Zekveld et al, 2011; Koelewijn et al, 2012; Kuchinsky et al, 2014; Ayasse et al, 2017; Ayasse and Wingfield, 2018), or when listeners are faced with sentences that express their meaning with complex syntax (Piquado et al, 2010; see Zekveld et al, 2018, for a review)
The better hearing group fell within the range considered clinically normal hearing for speech (PTA < 25 dB HL; Katz, 2002), while the participants in the poorer hearing group ranged from slight-to-moderate hearing loss

Summary

Introduction

The primary biological function of flexibility in the size of the pupil of the eye is to modulate the amount of light reaching the retina (Wang et al, 2016), pupil size responds to a range of psychological states (e.g., Kim et al, 2000; Kinner et al, 2017). In the domain of speech comprehension, the relationship between cognitive effort and pupil dilation appears in the form of an increase in pupil diameter while listeners are Hearing and Baseline Pupil Size attending to speech degraded by noise or reduced hearing acuity (e.g., Zekveld et al, 2011; Koelewijn et al, 2012; Kuchinsky et al, 2014; Ayasse et al, 2017; Ayasse and Wingfield, 2018), or when listeners are faced with sentences that express their meaning with complex syntax (Piquado et al, 2010; see Zekveld et al, 2018, for a review) In studies such as these, task-related changes in pupil diameter are typically expressed as a difference from a prestimulus baseline in the form of a brief silent period prior to presentation of the speech stimulus. The pupil size measured in this pre-stimulus window is referred to as the baseline pupil diameter (BPD; Kuchinsky et al, 2013; Koelewijn et al, 2015; Winn and Moore, 2018; Wagner et al, 2019)

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