Study Finds Learning by Repetition Impairs Recall of Details

Technique does enhance key facts in memories but blurs nuance and complexity.

When learning, practice doesn’t always make perfect.

UC Irvine neurobiologists Zachariah Reagh and Michael Yassa have found that while repetition enhances the factual content of memories, it can reduce the amount of detail stored with those memories. This means that with repeated recall, nuanced aspects may fade away.

In the study, which appears this month in Learning & Memory, student participants were asked to look at pictures either once or three times. They were then tested on their memories of those images. The researchers found that multiple views increased factual recall but actually hindered subjects’ ability to reject similar “imposter” pictures. This suggests that the details of those memories may have been shaken loose by repetition.

This discovery supports Reagh’s and Yassa’s Competitive Trace Theory – published last year in Frontiers in Behavioral Neuroscience – which posits that the details of a memory become more subjective the more they’re recalled and can compete with bits of other similar memories. The scientists hypothesize that this may even lead to false memories, akin to a brain version of the telephone game.

The image shows the hippocampus location in the brain.
Researchers proposed a Competitive Trace Theory, building on the hippocampus’ powerful capacity to orthogonalize inputs into distinct outputs. Credit NIA/NIH.

Yassa, an assistant professor of neurobiology & behavior, said that these findings do not discredit the practice of repetitive learning. However, he noted, pure repetition alone has limitations. For a more enriching and lasting learning experience through which nuance and detail are readily recalled, other memory techniques should be used to complement repetition.

Notes about this learning and memory research

Yassa and Reagh, a graduate student researcher in Yassa’s lab, are members of UC Irvine’s Institute for Memory Impairments and Neurological Disorders and Center for the Neurobiology of Learning & Memory. The study was conducted at Johns Hopkins University before the team relocated to UC Irvine in January. The work was supported by the National Institute on Aging (grants P50-AG05146 and R01-AG034613) and the National Science Foundation Division of Graduate Education (grant DGE-1232825).

Contact: Tom Vasich – UC Irvine
Source: UC Irvine press release
Image Source: The image is credited to NIA/NIH and is in the public domain
Original Research: Abstract for “Repetition strengthens target recognition but impairs similar lure discrimination: evidence for trace competition” by Zachariah M. Reagh and Michael A. Yassa in Learning and Memory. Published online May 8 2014 doi:10.1101/lm.034546.114
Full open access research for “Competitive trace theory: a role for the hippocampus in contextual interference during retrieval” by Michael A. Yassa and Zachariah M. Reagh in Frontiers in Behavioral Neuroscience. Published online August 12 2103 doi:10.3389/fnbeh.2013.00107

Open Access Neuroscience Abstract

Competitive trace theory: a role for the hippocampus in contextual interference during retrieval

Much controversy exists regarding the role of the hippocampus in retrieval. The two dominant and competing accounts have been the Standard Model of Systems Consolidation (SMSC) and Multiple Trace Theory (MTT), which specifically make opposing predictions as to the necessity of the hippocampus for retrieval of remote memories. Under SMSC, memories eventually become independent of the hippocampus as they become more reliant on cortical connectivity, and thus the hippocampus is not required for retrieval of remote memories, only recent ones. MTT on the other hand claims that the hippocampus is always required no matter the age of the memory. We argue that this dissociation may be too simplistic, and a continuum model may be better suited to address the role of the hippocampus in retrieval of remote memories. Such a model is presented here with the main function of the hippocampus during retrieval being “recontextualization,” or the reconstruction of memory using overlapping traces. As memories get older, they are decontextualized due to competition among partially overlapping traces and become more semantic and reliant on neocortical storage. In this framework dubbed the Competitive Trace Theory (CTT), consolidation events that lead to the strengthening of memories enhance conceptual knowledge (semantic memory) at the expense of contextual details (episodic memory). As a result, remote memories are more likely to have a stronger semantic representation. At the same time, remote memories are also more likely to include illusory details. The CTT is a novel candidate model that may provide some resolution to the memory consolidation debate.

“Competitive trace theory: a role for the hippocampus in contextual interference during retrieval” by Michael A. Yassa and Zachariah M. Reagh in Frontiers in Behavioral Neuroscience, August 12 2103 doi:10.3389/fnbeh.2013.00107

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