Distinct modulation of microsaccades in motor planning and covert attention

The degree of overlap between the mechanisms underlying attention control and motor planningremains debated. In this study, we examined whether microsaccades—tiny gaze shifts occurringduring fixation—are modulated differently by covert attention and motor intention. Eye movementswere recorded using high-precision eye-tracking. Our results reveal that whereas in a covertattention task, microsaccade direction was biased toward the attended location, in a motor planningtask, microsaccades were not directionally biased toward the cued location. Further, the rate ofmicrosaccades over time varied between the two tasks and whereas in the attention task a clearcorrelation emerged between microsaccade rate and visual detection reaction times across subjects,there was no relationship between microsaccade rate and reach/saccade reaction times. This studyadvances our understanding of the relationship between attention and motor processes, suggestingthat the mechanisms governing microsaccade generation are differentially influenced by motorplanning versus spatial covert attention engagement.