Dr. Wixted's research project is designed to enhance our understanding of memory in animals and to advance the comparative analysis of animal and human memory. Specifically, this project will investigate how well pigeons can remember a series of visual images presented in rapid succession. This procedure is analogous to one often used in human-memory studies in which people are asked to remember a list of words. Of primary concern is whether animals, like humans, remember items at the beginning or end of a series better than they remember middle items. In studies with human subjects, these "primacy" and "recency" effects are so commonly observed that they may be regarded as lawful properties of human short-term memory. In studies with animals, however, some researchers have obtained a robust primacy effect while others have reported its conspicuous absence. One explanation of these inconsistent findings appeals to the concept of "interference." According to this view, animals become confused when given many lists to remember in a single session because some of the items appear over and over again on different lists. Indeed, the only study to observe a primacy effect in birds arranged the experiment in such a way that items were never repeated within a session. An alternative explanation for the inconsistent findings appeals to differences between studies in temporal variables, such as delay of reward. Dr. Wixted will independently vary interference and delay of reward in an effort to clarify the conditions under which a primacy effect may be observed in animals. In addition to the immediate goal of helping to resolve apparently conflicting empirical findings, the results of Dr. Wixted's investigation may eventually facilitate the study of short-term memory disorders in humans by establishing the groundwork for relevant animal models.
