The Influence of the Number of Decision Branches on Saccade Latency

Saccades are rapid eye movements whose function is to bring new objects of interest to the fovea. A saccade is a ballistic movement: once it has begun, its trajectory cannot be altered. A single saccade takes about 150–200 ms to plan and execute (saccade latency). In the current study, the influence of the number of decision branches that are candidates of the saccadic target on saccade latency is investigated. Each presentation of the test display was preceded by a fixation stimulus, which is at the center of the screen. The test display consisted of white disks on a black background. The disks that were the same in size appeared at random positions. The task of the subject was to move the eyes to any of the targets as soon as possible. Saccade latency was shortest when one target was given. Latency was longer when more targets were given. This suggests that a display with more targets requires more time to choose target and plan of saccade.