Read this article with your right hand clenched into a fist. Then, after you're done, make a fist with your left hand. You might remember the next few paragraphs better than ever.
A new study led by Montclair State University’s Ruth Propper suggests that simply clenching one hand or the other can aid in memory. The study, published in the journal PLoS ONE and partially funded by the U.S. Army, found that a clenched fist can help engrave a memory on the brain, and call it up again later.
"The findings suggest that some simple body movements -- by temporarily changing the way the brain functions -- can improve memory,” Propper said in a statement Wednesday. “Future research will examine whether hand clenching can also improve other forms of cognition, for example verbal or spatial abilities.”
Propper and her colleagues recruited 50 right-handed people for their study. All participants were asked to memorize words from a 72-word list, and later prompted to recall as many of the words as they could.
The 50 subjects were split into five groups: one that clenched a rubber ball in their right fist for about a minute and a half while scanning the word list and right before trying to recall the words; another group did the same with the left hand. Two other groups alternated hands, clenching the right fist before reading, then the left before recall, and vice-versa. One control group did not clench their fists at all.
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When Propper and her team ran the numbers, they found that the group that did best on the memory test was the one that clenched the right fist while memorizing, and the left during recall. (The non-clenching control group also did pretty well.)
How does the hand lead to the brain? Previous studies have shown that clenching one’s left or right hand increases brain activity in the opposite hemisphere. Hand clenching has already been demonstrated to affect emotional states, and now, there’s a suggestion it may play a role in cognition as well. Propper and her colleagues think the left hemisphere and the right hemisphere may play important roles in the encoding and recall, respectively, of memory.
Big caveat: The current study offers no insight into memory tricks for left-handed people – whose brains are notoriously trickier for scientists to peer into -- but Propper and her team say they’ve tested southpaws and will be reporting that data elsewhere.
SOURCE: Propper et al. “Getting a Grip on Memory: Unilateral Hand Clenching Alters Episodic Recall.” PLoS ONE 8: e62474, 24 April 2013.