Categorizing sounds by pitch: effects of stimulus similarity and response repetition

Two experiments were performed to determine whether categorization of the pitch of a probe tone is influenced by the pitch of, and response made to, a preceding prime tone. The prime and the probe could be drawn either from a pool of low-frequency sounds or from a pool of high-frequency sounds. The results of both experiments indicated that the performance obtained was best when the prime and the probe were the same pitch (and therefore required the same response), intermediate when the two sounds differed in pitch and required different responses, and slowest when the prime and the probe differed in pitch but required the same response (i.e., they were drawn from the same frequency pool). The results of Experiment 2 revealed in addition that when a repeated response was required, performance declined as the magnitude of the frequency change increased and that responses were made more quickly and accurately if the direction of the frequency change was away from the alternative category than if it was toward the alternative category. The results demonstrate that categorization of sounds by pitch is accomplished with reference to a previous processing episode.