The Pupil Dilation Response to Auditory Stimuli: Current State of Knowledge

Abstract

The measurement of cognitive resource allocation during listening, or listening effort, provides valuable insight in the factors influencing auditory processing. In recent years, many studies inside and outside the field of hearing science have measured the pupil response evoked by auditory stimuli. The aim of the current review was to provide an exhaustive overview of these studies. The 146 studies included in this review originated from multiple domains, including hearing science and linguistics, but the review also covers research into motivation, memory, and emotion. The present review provides a unique overview of these studies and is organized according to the components of the Framework for Understanding Effortful Listening. A summary table presents the sample characteristics, an outline of the study design, stimuli, the pupil parameters analyzed, and the main findings of each study. The results indicate that the pupil response is sensitive to various task manipulations as well as interindividual differences. Many of the findings have been replicated. Frequent interactions between the independent factors affecting the pupil response have been reported, which indicates complex processes underlying cognitive resource allocation. This complexity should be taken into account in future studies that should focus more on interindividual differences, also including older participants. This review facilitates the careful design of new studies by indicating the factors that should be controlled for. In conclusion, measuring the pupil dilation response to auditory stimuli has been demonstrated to be sensitive method applicable to numerous research questions. The sensitivity of the measure calls for carefully designed stimuli.

Keywords: auditory processing; listening effort; pupil response; pupillometry; review.

Figure 1.

Overview of records that were identified, screened, excluded, and included in the review. The reasons for excluding the full-text articles are outlined in the text.

Figure 2.

Number of publications included in the present review as function of publication year. In total, 146 publications were included.

Figure 3.

Results of the current review. The figure shows the factors influencing the pupil size during auditory processing and the number of publications showing evidence for any effect of the factor on the pupil size. The findings are organized according to the Framework for Understanding Effortful Listening (FUEL). Several articles provided support for the effect of more than one factor. Please refer to Tables 1 and 2 for the relevant references associated with the factors described and for references in which no support was observed for the effect of these factors.