How long does it take to discriminate perceptual information? A study published online this week in Nature Neuroscience reports that monkeys need only about 30 milliseconds to distinguish perceptual information such as colors.
Studying perceptual speed is difficult, because it requires dissociating the time taken to perceive a stimulus from other processes, such as making an action to indicate what has been seen.
Emilio Salinas and colleagues avoided this problem by training monkeys to withhold the action ― which would indicate their perception of presented colored spots ― until they see a later cue. The scientists also construct a computational model to explain the processes underlying the monkeys' behavior, which confirms their data that a color needs to be presented for 30-50 milliseconds in order to influence the actions later made by the monkeys.