Decreases in the latency of smooth pursuit and saccadic eye movements produced by the ''gap paradigm'' in the monkey

The initiation of both pursuit and saccades was affected by the presence of a temporal gap between the disappearance of a fixated visual target and the appearance of a second, eccentric, target. For pursuit, the gap paradigm produced a modest (20 msec) decrease in latency, For saccades, the gap paradigm produced a similar modest decrease in the latency of some saccades, but also revealed a population of very short latency ''express'' saccades. The modest changes in the latency of pursuit and regular saccades displayed a similar dependence on gap duration, with the largest decreases produced by gaps of 200-300 msec. The gap paradigm did not produce ''express'' pursuit, even though express saccades could be elicited on interleaved trials.