Expecting questions modulates effort: Pupillometry (Chapman & Hallowell, 2020)

Purpose: Pupillary responses captured via pupillometry (measurement of pupillary dilation and constriction during the performance of a cognitive task) are psychophysiological indicators of cognitive effort, attention, arousal, and resource engagement. Pupillometry may be a promising tool for enhancing our understanding of the relationship between cognition and language in people with and without aphasia. Interpretation of pupillary responses is complex. This study was designed as a stepping-stone for future pupillometric studies involving people with aphasia. Asking comprehension questions is common in language processing research involving people with and without aphasia. However, the influence of comprehension questions on pupillometric indices of task engagement (tonic responses) and cognitive effort (task-evoked responses of the pupil [TERPs]) is unknown. We tested whether asking comprehension questions influenced pupillometric results of adults without aphasia during a syntactic processing task.

Method: Forty adults without aphasia listened to easy (canonical) and difficult (noncanonical) sentences in two conditions: one that contained an explicit comprehension task (question condition) and one that did not (no-question condition). The influence of condition and canonicity on pupillary responses was examined.

Results: The influence of canonicity was only significant in the question condition: TERPs for difficult sentences were larger than TERPs for easy sentences. Tonic responses did not differ between conditions.

Conclusions: Although participants had similar levels of attentiveness in both conditions, increases in indices of cognitive effort during syntactic processing were significant only when participants expected comprehension questions. Results contribute to a body of evidence indicating the importance of task design and careful linguistic stimulus control when using pupillometry to study language processing.

Supplemental Material S1. Stimuli used in this study.

Supplemental Material S2. Nouns, verbs, and associated psycholinguistic data.

Chapman, L. R., & Hallowell, B. (2020). Expecting questions modulates cognitive effort in a syntactic processing task: Evidence from pupillometry. Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2020_JSLHR-20-00071