This research will investigate the accuracy and speed with which people can retrieve material from memory; its aim is to account for dissociations between different kinds of performances which depend primarily on short-term memory. The aspects of short- term memory performance on which the research will focus include the accuracy with which people can retrieve memorized materials when they are asked to recognize them (studied via forgetting functions), the speed with which they can retrieve such materials (studied via reaction time or scan time), and the accuracy with which they can produce memorized materials when asked to recall them (studied via ordered recall or span). These measures are sensitive to differences in materials and between individuals. Though analysis of individual differences in performances in problem solving, reading, etc., shows that short-term memory is one good predictor of these performances, the various measures can show odd dissociations. For example, retrieval times and production in recall show related dependence on materials, but individuals whose performance is above average on one measure may not be above average on the other. This research will test a precise quantitative model of short-term memory performance. The core of the model is short-term forgetting, fairly directly measured by forgetting functions. Experiments will show whether, as the model suggests, retrieval time is tied primarily to speed of forgetting, while production or recall also is strongly affected by initial efficiency in learning. Experiments will outline the relations between the three aspects of short-term memory within individuals for different materials, including characters and words, both controlled and uncontrolled for phonemic complexity, and geometric and graphical items. The project aims to produce an accurate model to account for the common materials effects, explain the dissociation in measures for the individual, and to suggest how the various short-term memory measures should be interpreted with respect to their role in different kinds of mental tasks. Because of the dependence of so many tasks on short-term memory, the results of this research will bear on issues such as reading, problem solving, and decision making, as well as on education in these tasks.
