SEATTLE — A simple writing exercise can relieve students of test anxiety and may help them get better scores than their less anxious classmates, a study has found.

A report in the journal Science says students who spend 10 minutes before an exam writing about their thoughts and feelings can free up brainpower previously occupied by testing worries.

“We essentially got rid of this relationship between test anxiety and performance,’’ said Sian L. Beilock, an associate professor of psychology at the University of Chicago and coauthor of the study with graduate student Gerardo Ramirez.

Psychologists, educators, and parents have long known that the way students perform on a test does not necessarily indicate what knowledge they bring to the table. Test anxiety can lead to poorer grades and lower scores on standardized tests and college entrance exams.

The researchers found that students who were prone to test anxiety improved their test grades by nearly one grade point if they were given 10 minutes before an exam to write about their feelings. The researchers tested their hypothesis with college students in a lab setting and with high school students in the classroom, by first gauging the level of anxiety and then offering the writing intervention to some.

The researchers believe worrying competes for computing power in the brain’s “working,’’ or short-term, memory. If working memory is focused on worrying, it can’t help a person recall information the brain has stored. It also affects the working memory’s ability to stay focused. Beilock said the idea for the writing exercise came from the use of writing to combat depression.

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