Temporal patterns of eye movements reflect the complexity of a mental image

Abstract

Eye movements during mental imagery show a distinctive spatial and temporal pattern. While it has been known for a long time that fixation locations during mental imagery resemble those during perception, we showed in a recent study (Gurtner et al., 2019) that the temporal dynamics of fixations differ between perception and mental imagery. Using recurrence quantification analysis, we found that eye fixations return more often and sooner to previously inspected areas during mental imagery than during perception. To further investigate this difference we analyzed the role of re-fixations for maintaining mental images. In two experiments, we tested the hypothesis that systematic re-visits of a limited number of locations can counteract fading of the imagined content. In the first experiment, we manipulated the demands of maintenance by increasing the complexity of the pattern that needed to be maintained. In a second experiment, dynamic visual noise interfered with the mental image. The results contribute to a better understanding of eye movements during mental imagery by including the temporal dynamics of fixations in addition to spatial congruence.