The influence of bright background flicker during different saccade periods on saccadic performance.

We investigated saccades from central fixation to targets at 5 degrees to the left or right. These targets were red laser points of light with an intensity unmodulated in time (referred to as steady), while a bright background (76 cd/m(2)) was illuminated by a special fluorescent lamp, the output of which were series of light pulses (at frequencies of 50 or 100 Hz) that were presented only during certain periods, in synchrony with the saccade: e.g. during fixation of the central target, or during the latency (i.e. the period from target onset to saccade onset), or during the execution of the saccade; otherwise, the background luminance was steady. We observed a mean increase in latency of about 23 ms when 50 Hz flicker pulses occurred during the latency alone. This result is interpreted in terms of saccadic inhibition [Reingold & Stampe, (2000) In: Kennedy, Radach, Heller, & Pynte (Eds.) Reading as a perceptual process. Elsevier, Amsterdam]: our bright background flicker during the latency may have produced longer latencies, similar to the remote distractors in the model of Findlay and Walker [Behav. Brain Sci. 22 (1999) 661].