Psychology Professors Investigate Memory

For the past few years, UC Irvine’s professor of psychology and social behavior Chuansheng Chen has been collaborating in a cross-national and cross-university research study on the neural basis of learning.

The team delved deeper into the long-standing belief that learning requires repetition and that studying is more effective when spaced out rather than employing the popular “cramming” method used by many — especially students. The research group wished to study these various methods in efforts to explain the differences between the two.

“We tested two rival hypotheses: the encoding variability hypothesis and the reactivation or reinstatement hypothesis,” Chen said. “The former claims that repeated study helps because every time we study, we have slightly different memory traces of what we learn. Such variability helps us memorize the materials. The reactivation hypothesis, however, claims that repeated study improves memory because it reinforces the same memory trace again and again.”

Three studies were conducted at Beijing Normal University in which a total of 68 subjects participated.

In the studies, subjects were shown either words or faces multiple times in different order. During the process, the scientists used functional magnetic resonance imaging (fMRI) to observe the subjects’ brain activity.

“During the study, neither subjects nor researchers knew whether representational similarity in the brain would lead to a better or worse performance,” Chen said. “However, through similarity analyses of brain imaging data we collected from subjects while they were studying either words or faces multiple times, we found strong evidence supporting the reactivation hypothesis.”

The team’s finding challenges the previously established belief that people remember information better when they vary the contexts in which they study (i.e. location, time, etc.).

Rather, the study found that information was better retained when the same brain pattern was reactivated, resulting in more effective information retention than that of which occurred when brain patterns varied from one study session to the next.

Their study has recently been published online at ScienceXpress but will also be published soon in print.

Others that collaborated in the study include Gui Xue, first author of the paper and assistant professor (research) of psychology at University of Southern California, Russell Poldrack, professor of psychology and neurobiology at the University of Texas at Austin, Jeanette Mumford, Ph.D. in biostatistics at the University of Texas at Austin, Zhong-Lin Lu, professor of psychology and biomedical engineering at USC, and Qi Dong, Beijing Normal University.

“The study was one of teamwork in which all collaborators participated in getting grants, designing the study, examining the results and writing the article. However, the first author, Dr. Gui Xue, deserves most of the credit,” Chen said.

The study was supported by several grants from China, National Science Foundation (NSF) and National Institutes of Health (NIH).

The research team has plans to further investigate this area of study.

“We are planning to use single-unit recording and high-resolution fMRI (e.g., 7 Tesla) to further test our rival hypotheses and try to understand, on a more general level, why certain ways of learning are better than others,” Chen said.