Clenching your right hand may help form a stronger memory of
an event or action, and clenching your left may help you recollect the memory
later, according to research published in the open access journal PLOS ONE by Ruth Propper and colleagues
from Montclair State University.
Participants in the research study were split into groups
and asked to first memorise, and later recall words from a list of 72 words.
There were four groups who clenched their hands; One group
clenched their right fist for about 90 seconds immediately prior to memorising
the list and then did the same immediately prior to recollecting the words.
Another group clenched their left hand prior to both memorizing and
recollecting. Two other groups clenched one hand prior to memorising (either
the left or right hand) and the opposite hand prior to recollecting. A control
group did not clench their fists at any point.
What the study found
The group that clenched their right fist when memorizing the
list and then clenched the left when recollecting the words performed better
than all the other hand clenching groups. This group also did better than the
group that did not clench their fists at all, though this difference was not
"The findings suggest that some simple body movements -
by temporarily changing the way the brain functions- can improve memory. Future
research will examine whether hand clenching can also improve other forms of
cognition, for example verbal or spatial abilities," says Ruth Propper,
lead scientist on the study.
The authors clarify that further work is needed to test
whether their results with word lists also extend to memories of visual stimuli
like remembering a face, or spatial tasks, such as remembering where keys were
placed. Based on previous work, the authors suggest that this effect of
hand-clenching on memory may be because clenching a fist activates specific
brain regions that are also associated with memory formation.