An established body of research has shown that stress can affect memory negatively. However, there are some learning strategies we can use to counter this effect. New research suggests that taking practice tests might help.

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How we learn affects how much we remember in stressful situations.

A little bit of stress can be good for your memory, and there is an evolutionary explanation for it. By having a strong memory of a stressful event that put your life in danger, you are more likely to avoid similar situations in the future and thus survive longer.

However, too much stress can negatively impact your memory.

Our memory works as a three-staged process: encoding, consolidation, and retrieval. Stress can interfere with the encoding process by taking up a lot of your brain power, so often when we seem to have forgotten something, in fact, our brains have not stored the information in the first place.

Researchers from Tufts University in Medford, MA, decided to test whether a highly effective learning technique could protect our memory against the adverse effects of stress.

Retrieval practice vs. restudying

Researchers led by Ayanna Thomas, Ph.D., associate professor and director of the graduate program in psychology at Tufts University, examined whether retrieval practice can counter the adverse effects of stress.

Retrieval practice is a learning strategy consisting of taking practice tests.

Researchers examined 120 participants, all students.

Participants were asked to learn a set of 30 words and 30 images by looking at each item for a few seconds on a computer screen. Students also had 10 seconds to type a sentence using the item immediately after seeing it, in order to simulate note-taking.

Participants were then divided in half. One group studied using retrieval practice, the other using the conventional method of restudying the material.

The first group took practice tests where they had to recall as many items as possible, in no particular order.

The second group studied through repetition. The items were shown to them again on the computer screen, one at a time, for a few seconds each. Students could do this repeatedly, as they had several timed periods to study.

Memory tested after a stressful scenario

Both groups were then given a 24-hour break, after which half of the students in each study group were placed in a stressful scenario.

These students were unexpectedly asked to solve two maths problems and give a spontaneous speech with no preparation in front of two judges and three peers, all while being filmed.

During the same stress-inducing scenario, participants were given a memory test to see how many of the words or images studied the previous day they could recall.

Students were memory tested again 20 minutes later, after the stressful scenario had ended. This way, the scientists could test both immediate and delayed stress responses.

The rest of the participants took the same memory tests, but during and after a non-stressful task of equal length.

Test-taking practice reduces stress-induced memory impairment

Researchers found that when memory was tested immediately after inducing stress, those who had learned using retrieval practice had reduced stress levels.

Additionally, their memory was also protected against the negative effects of stress during the learning process.

Overall, those who used restudying practice remembered fewer items than those who used retrieval strategies, particularly after stress.

Stressed individuals who had used retrieval practice remembered approximately 11 items out of each set of 30 words and images, compared with 10 items remembered by non-stressed students.

Those who had used restudying practice and were stressed remembered an average of seven items, compared with the 11 items of their retrieval counterparts.

Restudying participants who had not been stressed remembered only a little under nine items.

"Our results suggest that it is not necessarily a matter of how much or how long someone studies, but how they study," says Amy Smith, graduate student in psychology at Tufts and corresponding author.

The results were published in the journal Science.

Negative effects of stress almost canceled completely

Although several studies have shown that stress reduces memory, there is not much research investigating whether learning strategies can reverse this negative effect, the authors note.

The new study by Thomas and team shows that learning information in an effective manner to begin with can counter the negative effects of stress.

"Even though previous research has shown that retrieval practice is one of the best learning strategies available, we were still surprised at how effective it was for individuals under stress. It was as if stress had no effect on their memory.

Learning by taking tests and being forced to retrieve information over and over has a strong effect on long-term memory retention, and appears to continue to have great benefits in high-stakes, stressful situations."

Amy Smith

The authors would like to point out, however, that individuals react differently to stressful situations, so further research is needed to expand on their results.

Thomas and team have already started working on additional studies that will hopefully replicate and add new insights into their findings.

Some of the researchers' new areas of interest include finding out if retrieval practice can benefit complex learning situations, such as acquiring a second language or other stressful scenarios that do not involve testing.

"Our one study is certainly not the final say on how retrieval practice influences memory under stress, but I can see this being applicable to any individual who has to retrieve complex information under high stakes," Thomas says.

She also recommends that educators use more frequent, "low-stakes testing" in their instruction, as this is more beneficial to students.

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