Modification of saccades through light stimulation

Brief flashes of light can alter the oculomotor behavior of tracking an intended target. A potential cause may be decreased visibility or disappearance of the target caused by visual masking due to the flash. This study performed a temporal analysis of saccadic eye movements when a brief 10 /spl mu/sec flash of white light was presented in the center, right or left visual field while subjects actively attempted to track a target that began along the midline and horizontally moved 15 degrees into the left or right visual field. Flash trials were compared to nonflash trials (control). Two temporal parameters were measured: the time to peak velocity and the time required for the response to attain /spl plusmn/one degree of the target. Compared with nonflash trials, the time to peak velocity increased. Yet, statistical significance was only observed when the flash of light was presented in the same visual field as the target, suggesting an ipsilateral masking effect. When comparing flash trials to controls, statistical significance was observed in the time it took to attain the target within /spl plusmn/one degree when the flash was presented in the contralateral, ipsilateral or center visual field of the target. The statistically significant changes observed are strongly speculated to be primarily attributed to visual masking; however decreased attention caused by distracters as well sensory overload due to after-images also caused modifications in saccadic behavior.