Saccades predict and synchronize to visual rhythms irrespective of musical beats

Music has been shown to entrain movement. One of the body's most frequent movements, saccades, are arguably subject to a timer that may also be susceptible to musical entrainment. We developed a continuous and highly-controlled visual search task and varied the timing of the search target presentation, it was either gaze-contingent, tap-contingent, or visually-timed. We found: (1) explicit control of saccadic timing is limited to gross duration variations and imprecisely synchronized; (2) saccadic timing does not implicitly entrain to musical beats, even when closely aligned in phase; (3) eye movements predict visual onsets produced by motor-movements (finger-taps) and externally-timed sequences, beginning fixation prior to visual onset; (4) eye movement timing can be rhythmic, synchronizing to both motor-produced and externally timed visual sequences; each unaffected by musical beats. These results provide evidence that saccadic timing is sensitive to the temporal demands of visual tasks and impervious to influence from musical beats.