Increase in saccadic peak velocity with increased frequency of saccades in man.

Twelve normal subjects (aged 22-80 yr, mean 47 yr) performed three blocks of 20 saccades made to LED targets stepped back and forth. The first and last blocks were performed at a (slow) rate of 0.18 Hz, while the middle block was performed at the faster rate of 1.15 Hz. Mean saccadic amplitude was unaffected by saccade rate, but latency and duration became shorter at the higher frequency. Most interestingly, the peak velocity increased by approx. 6% when saccades were performed at the higher rate. This increase was statistically significant, even after normalization for saccade amplitude. That saccadic frequency may affect saccadic peak velocity must be considered as a potential variable when analysing saccades.