Temporal factors in target selection with saccadic eye movements.

Decision times involved in selecting visual targets with saccadic eye movements in rhesus monkeys were studied for three tasks in which single targets, paired targets with varied asynchronies, and multiple targets requiring a discrimination were presented. Probability of target choice in the paired-target task was strongly influenced by target luminance and size as specified by the temporal offset required to yield equal probability choice. Among the animals tested, reaction times for target selection in the paired-target task took 12-47 ms longer, and in the discrimination task 17-70 ms longer than for generating saccades to single targets, thereby reflecting the decision times involved. The results provide information about the time-course of decisions involved in selecting visual targets with saccadic eye movements.