Recognition memory for pitch of fixed and roving stimulus tones

The method of delayed comparison was used to measure pitch memory under two conditions of presentation, either the same standard tone on every trial (fixed S) or one of four equally likely standard tones (roving S), six durations of interference interval ranging from 0.0 to 4.0 sec, and two types of interference interval, either blank or filled with a pure tone. Listeners were instructed not to rehearse the S tone during the interference interval. For both fixed-S and roving-S conditions, accuracy of performance, as measured by area under the ROC curve, declined as interval duration increased and declined more rapidly following an interference-filled than following a blank interval. In general, forgetting proceeded at a slower rate under fixed-S conditions than under roving-S conditions. A second experiment showed that very little forgetting is obtained over 4 sec for roving-S conditions if instructions permit rehearsal of the S tone and suggests that the conclusions from the first experiment be restricted to nonrehearsal instructional conditions.