Distinct modulation of microsaccades in motor planning and covert attention

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