[The difference in saccadic parameters among several visually guided tasks]

The present study was undertaken to establish the effects of the five different paradigms (simultaneous, gap, overlap, delayed-memory and anti-saccade tasks) on saccade dynamics (duration, peak velocity, and amplitude).

We recorded ocular movements in 7 normal subjects, using infrared oculography with a visual stimulation system.

The distribution of saccade accuracy in gap and overlap tasks had about the same steepness as that in simultaneous tasks, but that in delayed-memory and anti-saccade tasks was broader than that in simultaneous tasks. The distribution in anti-saccade tasks had a marked intersubject variability, and the average values of accuracy were hypermetric in four subjects. The peak velocity/amplitude ratio in simultaneous and gap tasks were higher than those of other tasks. The relationship between average of peak velocity of abduction and adduction was different, adduction was higher than abduction in simultaneous and gap tasks, and abduction was lower than adduction in delayed-memory and anti-saccade tasks.

The dynamics in simultaneous tasks had about the same characteristics as in gap tasks, but were different from those in overlap, delayed-memory, and anti-saccade tasks. These results indicated that the marked differences in dynamic properties among different saccade types may reflect processes in the visuomotor system.