ABSTRACT
Forgetting and memory received study in ancient times in terms of learning mnemonic systems required during the course of scholastic training (Highbee, 1977). The actual scientific study of forgetting has come only recently with the pioneering work of Ebbinghaus (1885) and by the study of the delayed response task in lower animals by Hunter (1913). Hunter’s work was the first attempt to compare memory performance across species. Unfortunately, the task suffered from the emphasis it placed on the animal’s particular body orientation to bridge the time delay. (Ruggiero & Flagg, 1976) If the animal oriented toward the correct choice during the delay, then conceivably perfect performance could be maintained across any memory interval. The delayed matching-to-sample task improved upon this procedure by using an instructional stimulus (sample). Choices were not presented until after the delay interval, and varied randomly in their location. Thus, simple orientation to one side or another could not be used to bridge the delay interval. One variation of the delayed matching-to-sample task (Konorski, 1959; Nelson & Wasserman, 1978) is to present only one choice stimulus and require that the subject (e.g., a pigeon) identify it as either being the same as the sample stimulus (by pecking it) or different from it (by not pecking it). Alternatively, the pigeon could be presented with two report keys. A peck on one could be defined as correct when the stimuli were the same and a peck on the other when they were different (cf. Wright, 1972). This is a Same/Different task. The Same/Different task is also a serial probe recognition task with one list item.
