The effect of distractor on memory for pitch: trace distortion or interference with retrieval?

The effect of the time of presentation of an interpolated stimulus on dynamic memory for pitch of pure tones of 900-2000 Hz was investigated by comparison of successive stimuli. The test tone followed the sample tone after 25, 40, 60, 80, 160 or 320 s. The interpolated stimulus (a pure tone of 220 Hz) was timed either 20 s before the test tone (Experiment I) or 20 s after the sample (Experiment II). The effect of the interpolated stimulus on memory for pitch was found to vary with the time interval between this stimulus and the test tone. An interfering effect was observed when this interval did not exceed 40 s. No variation in effect occurred within this time limit. These findings suggest that the distracting stimulus interferes with the retrieval of the memory trace of the sample tone rather than with the trace itself.