Pupillary responses signify more than just effort: Windows into processing, prediction, reflection, and uncertainty

Pupil dilation has long been used to index effort or general cognitive arousal in a variety of tasks. Traditionally, the main outcome measure is peak pupil dilation or the mean pupil dilation within some target window. In this talk, we explore how the time course of the growth and decay of pupil dilation can lend further insight into auditory processing. A series of pupillometry experiments revealed elevated listening effort resulting from various influences such as poor spectral resolution, unpredictability of sentence content, selective attention, or the need to reflect on what was heard to produce a creative response. Peak and mean pupillary responses generally confirmed original hypotheses, but more interesting findings emerge upon inspection of unforeseen trends in the data. Specifically, the timing of the pupil decay response can arguably be interpreted as a signature of the completion of sentence prediction, or the completion of processing that relies on memory trace (rather than perception) of the signal. The ultimate goal of this discussion is to unpack a new approach to pupillometry experiments that is aimed at separating processing that stems from perception versus processing that stems from cognitive processing, or reflecting upon a memory trace of the stimulus.