Trial-to-trial carryover in auditory short-term memory.

Using a short-term recognition memory task, the authors evaluated the carryover across trials of 2 types of auditory information: the characteristics of individual study sounds (item information) and the relationships between the study sounds (study set homogeneity). On each trial, subjects heard 2 successive broadband study sounds and then decided whether a subsequently presented probe sound had been in the study set. On some trials, the similarity of the probe item to stimuli presented on the preceding trial was manipulated. This item information interfered with recognition, and false alarms increased from 0.4% to 4.4%. Moreover, the interference was tuned so that only stimuli that were very similar to each other interfered. On other trials, the relationship among stimuli was manipulated to alter the criterion subjects used in making recognition judgments. The effect of this manipulation was confined to the trial on which the criterion change was generated and did not affect the subsequent trial. These results demonstrate the existence of a sharply tuned carryover of auditory item information but no carryover of the effects of study set homogeneity.