Douglas L. Hintzman - US grants

Previous NSF-supported research by Hintzman has shown that a simple theory of human memory, based on a few core assumptions, can account for a surprising number of empirical phenomena uncovered in experiments on human learning and memory. The basic assumptions of the theory have been formalized in computer programs, which have been tested on learning and memory tasks analogous to those given to humans participanting in experiments. Such simulation work is a valuable aid in the development of theories of cognition, particularly theories involving factors such as parallel processing and variability, whose consequences are difficult to anticipate intuitively. The basic assumptions of the Hintzman simulation model, for example, concern processes underlying the operation of just two fundamental variables, repetition and similarity. However, the model accounts for several phenomena that previously had been thought to be unique, and to require their own ad hoc explanations. The research will consist of three types of activity: (a) The simulation model will be expanded in two ways. First, the present model, which has so far been applied primarily to memory for distinct events and the learning of abstract categories, will be applied to the domains of associative learning and recall. Second, different versions of the model will be developed to handle problems for which the present model is inadequate. These include retrieval of the meaning of a word from memory, and the facilitative effect of prior familiarity on learning. (b) Several experiments will test new predictions made by the model concerning the learning of abstract categories, the effects of repetition and similarity on recognition of previously encountered items, and memory retrieval latencies. (c) Comparisons will be made between the present memory model and other models in the literature. Interest will focus primarily on determining whether a simple model of the "connectionist" type exists whose behavior is essentially the same as that of the current model. This is important because an advantage claimed for connectionist models by some is that they are anatomically or physiologically plausible. The theory has broad implications for learning, memory, and cognitive processes. As such, it could yield practical insights in the fields of education and training, memory improvement, treatment of memory defects, and the reliability of judgments based on memory.

This research will extend previous work developing a computer simulation model of human memory. The project includes two kinds of activities. First, the research will use simulation to explore interesting properties of the model in greater depth and to apply the model to human memory phenomena that were not considered in its initial development. Second, the research will include experiments on human memory, in order to better understand the reasons behind several of the model's apparent predictive failures. These experiments will focus on how information is retrieved from memory and how judgments regarding remembered events are based on the retrieved information. The questions to which the experiments are addressed are general ones, not model-specific, so that the experimental results will be of broad relevance to theories of human memory. Although this work is unlikely to have immediate practical application, it will further our understanding of the properties of human memory and its role in cognition, and so will contribute in the long run to applications in such areas as education and training, brain damage and amnesia, and biases in human judgment and decision making.

9319265 HINTZMAN This project will study how information is retrieved from human memory; it will focus on the detailed time course of retrieval of different kinds of information about single items in memory. The experiments will require people to make a dichotomous decision about a test item (a word or picture); the method will manipulate the amount of time the person is allowed before being required to make a response. By varying that amount of time, it is possible to determine the earliest point in the retrieval episode at which an individual's decision accuracy rises above chance (the intercept). Previous research has suggested that different kinds of information may be characterized by different intercepts, in the range of 300-550 ms. These experiments will explore intercepts for a range of memory-based judgments, including judgments of generic information (knowledge acquired before the experiment began) and episodic information (acquired in the experimental context). They will also examine effects on intercepts of such fundamental experimental variables as repetition, recency, and similarity. The research will include the development of computer simulation models, as an aid in interpreting the results. The findings will help shape theories of memory systems, memory representation, retrieval, and memory-based decision making, and thereby contribute more generally to our understanding of the role of memory in cognition. The work should contribute in the long run to applications in such areas as education and training, brain damage and amnesia, and biases in human judgment and decision making. ***