Two dissociable updating processes in working memory
Although multiple reviews have already been published on the topic of pupil dilation and its link with a broad range of cognitive processes (Andreassi, ), a comprehensive review on recent studies that have investigated pupil dilation in the context of cognitive control tasks is still missing. For a comprehensive review of older studies on the topic of pupil dilation and cognition, the reader is referred to earlier work (Beatty & Lucero-Wagoner, The present review focusses on studies that have investigated pupil dilation during cognitive control tasks.
In this context, pupil dilation refers to the stimulus-induced increase in pupil diameter relative to a pre-stimulus baseline period (also known as the task-evoked pupillary response; Goldinger & Papesh, ).
Pupillometry research has experienced an enormous revival in the last two decades.
This is particularly important because, despite our increased understanding of the neural and computational mechanisms underlying cognitive effort, interpreting behavior in terms of cognitive effort risks circular reasoning (Navon, ). For this task, the difference in reaction time for incongruent versus congruent trials, i.e., the Stroop effect, is typically used as a measure of task performance.
Without considering an independent measure of cognitive effort, it is hard to estimate from the mean reaction times how much effort the participant exerted.
Although pupil dilation has been investigated since the early 1960s (Hess & Polt, ), pupillometry research has experienced an enormous revival in the last two decades.
In contrast to the early pioneering work, pupil dilation is relatively easy to study nowadays; eye trackers are relatively cheap and typically provide adequate temporal resolution and precision to detect even relatively small changes in pupil diameter.