Temporal discrimination factors in the delayed matching-to-sample task in monkeys

The temporal discrimination hypothesis (TDH) of delayed matching-to-sample (DMTS) stresses the animal’s ability to discriminate which choice-stimulus alternative has appeared most recently as sample. Thus, the emphasis is placed on discriminative processes, temporal in nature, rather than on the traditional trace or buffer storage mechanisms of short-term memory. Some of the predictions of the TDH were tested within the context of the DMTS task. Experiment I showed that the difficulty of sample-stimulus sequences could be predicted by the TDH. Experiment II showed DMTS performance to be an increasing function of the number of sample stimuli employed, a result predicted by the TDH, but not by a traditional proactive interference interpretation. The results demonstrate the importance of temporal discriminative processes in DMTS. The possibility for a simpler theoretical approach to memory, in general, is discussed.