Anxiety helps memory recall, but stress hinders complex problem solving

Pre-test jitters make it easier to recall memorized facts, but that stress also makes it tough to solve more complex problems.

Researchers at Ohio State University gave a battery of simple cognitive tests to 19 first-year medical students one to two days before a regular classroom exam – a period when they would be highly stressed. Students were also given a similar battery of tests a week after the exam, when things were less hectic.

While pre-exam stress helped students accurately recall a list of memorized numbers, they did less well on the tests that required them to consider many possibilities in order to come up with a reasonable answer. A week after the exam, the opposite was true.

"Other studies have suggested that elevated stress levels can actually improve some aspects of cognition, particularly working memory," said Jessa Alexander, a study co-author and a research assistant in neurology at Ohio State. "The results of the two problem-solving tests we administered suggested a decline in problem solving abilities that required flexible thinking."

She conducted the study with David Beversdorf, an assistant professor of neurology at Ohio State. The two presented their findings on October 25 in San Diego at the annual Society for Neuroscience conference.

"We already know how the immune and endocrine systems of healthy medical students react to stress, along with how students respond behaviorally to this kind of stress," Beversdorf said.

"But how students react cognitively has largely been ignored."

The researchers gave 19 medical students three tests each. The first test assessed short-term memory – students listened as the researchers read strings of up to 9 numbers. The students were then asked to write down the exact sequence they had just heard.

The other tests evaluated how well the participants could solve specific problems. In one test, students were given a list of three words and asked to think of one word that, when combined with each of the three given words, would make compound words or a short phrase. For example, students were given way, ground and weather, for which the answer was "fair," to create fairway, fairground and fair-weather.

For the second problem-solving test, students were to fill in the only blank spot on a grid that had a series of shapes and symbols. They were given a list of possible solutions and asked to choose the shape or symbol that best fit with the other shapes in the grid.

Students performed better on the memory test one to two days prior to the exam, when their stress levels were presumably at their peak, and worse on the problem-solving tests.

A week after the exam, students were given a similar round of cognitive tests. This time, the students did slightly worse on the memory test, but had improved on the word and shape tests.

"There was a clear relationship between cognitive function and stress levels," Beversdorf said. "The students didn't think flexibly right before their exam, typically a time of great stress."

During acute stress – which many medical students experience prior to an exam – the body releases a compound called norepinephrine. Known as a "fight or flight" compound, norepinephrine allows the body to react quickly to an immediate threat.

While measuring norepinephrine levels was beyond the scope of this study, based on findings in other studies the researchers think that elevated levels of the compound prior to an exam may have helped boost students' memories.

"Even though norepinephrine may help a student recall memorized facts, it could also hinder his ability to think flexibly – that is, to solve problems that require selecting one of many possibilities using associative information," Beversdorf said. "Right before the exam, students had more difficulty answering the problem-solving questions."

The researchers are collecting more data from a new group of medical students this fall. Future work may lead to efforts to help quell pre-exam anxiety.

The National Institute on Drug Abuse and the National Institute of Neurological Disorders and Stroke funds Beversdorf's research.