The differentiation of visually guided and anticipatory saccades in gap and overlap paradigms

Saslow and others have shown that the latency of foveating saccades can be altered by changing the offset time of the current fixation point relative to the onset of the peripheral target. Whether anticipatory saccades contributed to these results was not known. By the criteria of direction error and amplitude error the minimum latency for visually guided saccades is 110-130 ms for three subjects and 160 ms for a longer latency subject. Excluding anticipatory responses did not eliminate offset-onset effects. The genesis of express saccades and the role of higher neural levels is discussed.