Backward recognition masking in relative pitch judgments.

Backward recognition masking refers to interference of a second masking tone with recognition of a target tone presented earlier in time. The degree of interference has been found to decrease as the length of the silent interval separating the two tones increases. These results have been interpreted as representing interference of the masking tone upon the preperceptual storage and perceptual resolution of the target. It is logically possible, however, that the masking tone does not interfere with perceptual resolution but interferes with comparison of the target to a long-term memory representation. The current research was designed to provide a critical test of this alternative hypothesis by modifying the backward recognition masking task. Subjects determined whether the masking tone was higher or lower in pitch than the target tone. The frequencies of the target and masking tones varied randomly across trials. This ensured that the task could not be performed by comparing the target to a representation in long-term memory. Nevertheless, masking was obtained in this task, arguing against the comparison argument and in favor of the perceptual resolution interpretation. Given that masking was obtained under both ipsilateral and contralateral presentation of the tones, the results argue for a central preperceptual auditory storage that holds information after the inputs from the two ears are combined in the auditory system.