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Updating Memory and Remembering Changes

Successful navigation of dynamic environments requires updating memory to adapt to changes. Research has often shown that event changes impairs memory for specific details. A classic finding is that more competing details makes it harder to remember specific events. We propose that this inteference can be eliminated when people integrate current events with similar but not identical memories by looking back in memory to compare details of the past and present. We have shown  this in: paired associate learning, memory for contradictory political views, corrections of real-world fake news, and the observation of changes in everyday actions.  

We are now conducting experiments to: 1) examine how kinds of retrieval cues promote integrative encoding when fake news is corrected, 2) characterize the association between task engagement and comprehension of everyday action changes, 3) identify individual differences associated with cognitive control abilities, and 4) directly compare updating of episodic and semantic memories.

We are also currently designing experiments that use eye tracking to provide physiological indices of the roles of sustained attention and mnemonic prediction errors in memory updating.

Individual and Age Differences in Free Recall Dynamics

Context theories of episodic memory propose that the ability to isolate prior events during retrieval depends on the match between the contextual information available at retrieval at the contextual representations that are stored with target information. Free recall tasks are thought to depend heavily on the ability to self-initiate context reinstatement, making them ideal to investigate the role of context utilization in episodic memory. The ability to utilize contextual information varies as a function of working memory capacity (WMC), with high-WMC individuals showing more effective context utilization than low-WMC individuals. We are currently examining how episodic memory retrieval in a highly context-dependent task (free recall) depends on WMC ability.

We are also investigating the role of context processing in age-related episodic memory deficits. An inevitable consequence of healthy aging is impairment in the ability to remember prior episodes. Age-related episodic memory deficits are most pronounced when little environmental support is available to cue earlier memories. These deficits are also heightened when similar memories compete during retrieval. This line of research is aimed at understanding the mechanisms that underlie age-related episodic memory deficits in free recall from multiple sources of information.
In this research, we use analyses of retrieval dynamics and computational models to examine how people who differ in their use of context constrain memory search and reject intrusions from other events. We are currently examining how context processing abilities interact with stimulus and task characterstics, thus leading to differences in how people initiate retrieval, monitor its accuracy, and decide what memories to report.

Mnemonic Discrimination

The ability to discriminate sensory inputs from memories of similar but non-identical events is referred to as mnemonic discrimination. This behavioral outcome may be supported by hippocampal pattern separation that encodes unique sensory inputs so that they do not competing with similar existing memories. Mnemonic discrimination can be measured using modified recognition tasks that in which people study objects and later have to discrimination representations of those objects from similar lures (e.g., a different glass of red wine). Such lure discrimination has been used to assay hippocampal integrity across populations know to have selective memory impairment.

We are currently using a mnemonic discrimination task to examine acute exercise effects on hippocampal function in middle-aged adults at risk for Alzheimer's Disease as well as impairments in lure discrimination in children and adolescents at risk for schizophrenia and in healthy older adults.

Our investigations also include neural measures of functional connectivity associated with lure discrimination deficits. We are planning to extend this work to examine the role of attention during encoding in subsequent lure discrimination using subjective reports of task engagement and pupillometric measures associated with sustained attention.

Finally, we recently extended this work to examine the computational memory mechanisms underlying the "other race effect" that is the tendency for people to better recognize faces from the same race rather than other races.

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