Focal attentional level while tracking a smoothly moving target influences saccadic dynamics

It was investigated whether saccadic dynamics change and how such changes occur when focal attention directed to a moving target was raised while tracking the target. Three tasks were conducted: feedback task, high brightness task and low brightness task. The feedback task, which was a similar method to the previous method (see Y.Ebisawa, et al., Proc. Ann. Int. Conf. IEEE Eng. Med. Biol. Soc., 12, p. 965-7, 1990), was used to raise the subjects´ attention. Under the task, the eye velocity was monitored. When the SP velocity was higher than a sliding threshold the target was set at a high brightness state. In contrast, when it was below the threshold the target was set at a low brightness state. The subjects were asked to follow the target so that the target became as bright as possible. Under the high and low brightness tasks, the target was always set at a high and low brightness state, respectively. The subjects were asked to follow the target naturally. The results showed that smooth pursuit eye movement (SP) gain increased and saccadic amplitude decreased in the feedback task, compared to the other two nonfeedback tasks. These coincided with the previous results. In addition, the saccadic peak velocity in the feedback task was largest of all the tasks, while there was the inconsiderable difference between the high and low brightness tasks. This suggests that the peak velocity of saccades increases when the focal attention is raised