The precision of choice reactions.

Abstract

An auditory signal was presented either to the right or to the left of the subject, and he had to react in the corresponding direction with a 1-in. movement to the right or a 2-in. movement to the left. A criterion that combined time and precision had to be met. In the one-choice condition he knew in advance the direction and time of presentation of each signal, since the sequence of signals was arranged in a simple pattern that was learned before the condition was performed. In the two-choice condition he was told in advance that there were only two possible times of presentation, and only two possible directions of the signal, but that the order was random. It was found that the one-choice condition was performed with greater precision than the two-choice condition. There was no difference in the two-choice condition between the two possible times of presentation of the signal. Thus 50% of catch tests had no effect in this condition. When the two-choice condition was performed after the one-choice condition, reaction times were about .05 sec. shorter than those usually reported. There was evidence of an interaction between the 1-in. and 2-in. movements.