Temporal Dynamics and Selection Mechanisms of Visual Memory Consolidation

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Project Summary Our ability to hold information in working memory is related to almost every aspect of our cognition, including fluid intelligence. Deficits in working memory have been implicated in many psychological disorders including Schizophrenia, Alzheimer's Disease, ADHD, and in normal aging. However, even after decades of research, many fundamental questions about the mechanisms underlying working memory remain unanswered. We have demonstrated that several experimental results which have been thought to characterize visual working memory in fact reflect fundamentally different processes, including visual sensory memory and response strategies. Here we propose to further isolate memory storage mechanisms from other processes, so that accurate theories of information processing and storage can be developed. In particular, we propose a comprehensive approach for characterizing the nature of how visual information is transferred into the working memory store, a process termed memory consolidation. The development of novel behavioral paradigms, mathematical modeling techniques and neurophysiological techniques will provide a platform for examining the process of visual memory consolidation with unprecedented precision. By characterizing the mechanisms of consolidation, the results of this work will also be informative for the many processes related to it including attention and working memory storage. We first examine the small number of previous studies on consolidation, and suggest that recent research on working memory retention explains why these studies have provided conflicting results. An experimental approach for examining the consolidation process is developed that mitigates these issues by removing retention intervals from memory paradigms. Preliminary results show that doing so provides a parsimonious experimental design that is uniquely powerful for examining the time course of memory consolidation. In Aim 1 this approach is used to characterize properties of consolidation for color, shape, and face information. Comparing the results across these levels of visual complexity will provide novel insights into memory consolidation and storage. In Aim 2 a similar approach is used to examine not only how visual features are consolidated, but also how the binding between multiple features of an object becomes consolidated into working memory over time. By examining the mechanisms of consolidating feature bindings, the results will also shed light on how this information is eventually represented within working memory. Whereas these and previous experiments consider the consolidation of very briefly presented information, in natural environments we may spend several seconds encoding a scene. Therefore, the goal of Aim 3 is to use this new paradigm, combined with eye tracking electrophysiological approaches (EEG), to measure how visual information is dynamically consolidated during extended viewing periods. Taken together the results of these studies will greatly advance our understanding of how visual information gets consolidated into memory. Moreover, the development of new experimental and analytic approaches will provide research tools that will be useful in many areas of psychological research.