ON THE INTERACTION OF S-R COMPATIBILITY WITH OTHER VARIABLES AFFECTING REACTION TIME.

Choice reactions to tactual stimulation were studied, using compatible instructions (react with the finger that is stimulated) and incompatible ones (react with the corresponding finger on the other hand). It was found that decrease in compatibility increased the effect of number of alternative reactions, of uncertainty about the time of arrival of a stimulus, of a simultaneous distracting task, and of an unequal frequency of arrival of different signals. It was also noted that no significant interaction was found between time uncertainty and number of alternative signals; and that stimuli with a fixed probability of occurrence gave slower reactions when several different stimuli were presented in intervening trials, than when there was only one. The results are interpreted as according with a theoretical mechanism resembling a statistical decision.