Eye Movements Reflect Listening Effort and Visualizable Speech

Eye movements can index the recruitment of cognitive resources. During listening, increased effort is associated with reduced eye movements. However, eye movements also support mental imagery, suggesting that reduced eye movements during effortful listening may reflect the difficulty of creating mental images to support speech comprehension. Here, we examined how speech content and listening difficulty interact to shape eye movements during listening and later recall. Young adults listened to, and subsequently recalled, descriptions for which rich, visual details were (i.e., concrete descriptions) or were not (i.e., abstract described) spoken in different levels of background noise (easy vs hard) while eye movements were recorded. During listening, fixation rate, saccade amplitude, and gaze dispersion decreased under difficult listening conditions and for concrete descriptions. Gaze dispersion timecourses tracked spatial-relational words, but not other relational content, in concrete descriptions. During recall, eye movements were lower for concrete descriptions, particularly when encoded under hard listening conditions. Notably, gaze dispersion peaked before the recall of spatial-relational details, especially in participants with higher recall accuracy. Together, these findings suggest that listening effort shapes eye movements, while visualizable speech content elicits distinct patterns in which eye movements may be co-opted to represent imagined space and support memory accuracy.