Research on visual memory has indicated that the features of visual memory representations are lost at different rates, rather than decaying as bound representational units. While the research on visual memory representations has provided information on how observers retain and lose visual information, there is no corresponding research on auditory memory representations. The purpose of this study was to examine how the features of auditory representations are lost over time. All participants completed a study block, followed by a test block. During the study block, participants were presented with 128 environmental sounds and were instructed to try to commit the sound to memory. During the test block, each participant was presented with 128 randomized sounds, 64 "old" sounds which had been presented in the study block and 64 "new" foil sounds that had not been presented in the study block (the new sounds were either completely new, a same-category exemplar of a studied sound, or a state exemplar of a studied sound object in a new position or spatial environment). Participants were instructed to classify each sound as old or new. This task revealed differences in recognition performance on the different types of memory foils, indicating differences in the rate that features decay from auditory memory representations. Acoustic features of the auditory memory representations decayed more rapidly than the semantic, categorical information. The results suggest that the features of auditory memory representations are lost at different rates, rather than decaying as bound units.
