The Time Course Of Attention Shifts Before Endogenous Saccades

There involves two means in the process of visual selection: overt saccadic action and covert attention shift. Both facilitate processing to the selected object. In light of that, the relationship between saccades and attention shifts has been focused on more and more. Based on different causes, saccades can be classified as endogenous ones and exogenous ones. As saccadic researchers focus on more initiative endogenous saccades instead of exogenous previously, in visual selection field there emerge a number of studies on the relationship between endogenous saccades and attention shifts, most of which believe the strong coupling between the two. Still some indicated attention shifts precede endogenous saccades, but few concerned about shift change tendency following times.Using eye tracking method(Eyelink II eye tracker), students in university as the subjects(half male, ages from 18 to 25 ), the present paper examined the time course of allocation changes of attention to saccadic targets before endogenous saccades, which was based on the fact that attention shifts precede saccades having been confirmed by us in a dual-task paradigm, and then effect of targets'locations on attention shifts. Two researches were included, both of which used mean performance of the target discrimination as indicator of attention shifts. In the first research, attention shifts happening under endogenous saccades and fixation were compared. We also tried to explore shift change tendency following times when participants were asked to have saccades. It was explored more in the second research using more meticulous time dimension, and effect of targets'location on attention shift was also discussed.The data demonstrates that:1. attention shifts directing to saccadic targets precede endogenous saccades. The mean discrimination performance of participants to peripheral targets under saccadic condition is significantly more than fixation condition.2. attention shifts happen at the beginning of preparing stage of endogenous saccades. Once a saccade is known to make, attention shift begins quickly, and runs most fast at the first 50ms to 100ms more or less. Then the speed slows down at 90ms to 100ms more or less, but still goes on increasing, after that it gradually goes smoothly. Seeing overall process, the allocation of attention to endogenous saccadic target significantly increases as the time going ahead, that is, the mean discrimination performance of participants to peripheral targets is more and more better.3. the distance between saccadic target and fixation point has no significant effect on attention shifts following time. But in all time course, allocation of attention shift to target reduces as the distance grows. The mean discrimination performance of participants to farther targets is worse than nearer relative to fixation point.