Influences of Target and Fixation Point Conditions on Characteristics of Visually Guided Voluntary Saccade

Abstract

Three experiments were conducted. In each experiment, a fixation point (FP) simultaneously appeared in the center of a monitor with the saccade target (ST), which was presented randomly either 4 deg or 8 deg to the right of the FP. Four subjects were instructed to fixate on the FP for one second (as judged by each subject) after the appearance of the ST and to then make a single saccade to the ST. The ST Diameter, ST luminance, and FP diameter were changed randomly in each experiment, independently. The results were as follows. (1) The larger or brighter ST significantly decreased the normalized saccadic peak velocity (NSPV) as well as the saccadic amplitude. (2) The larger FP significantly decreased the saccadic amplitude and the NSPV. Some recent physiological findings suggested that the strength of the fixation before saccade generation had produced these results.