If you're looking for a quick memory fix, move your eyes from side to side for 30 seconds, researchers say.
Horizontal eye movements are thought to cause the two hemispheres of the brain to interact more with one another, and communication between brain hemispheres is important for retrieving certain types of memories.
Previous studies have suggested that horizontal eye movements improve how well people recall specific words they had just seen. But Andrew Parker and his colleagues at Manchester Metropolitan University in England wanted to know whether such eye movements might also help people recognize how they'd seen those words.
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Recognition memory differs from recall memory in that people trying to recognize words tend to make false memory errors called source-monitoring errors.
This occurs when they recognize words but attribute their familiarity to the wrong source — they might think they just read the words, when they had actually heard them in a conversation earlier that day, for example.
To test whether horizontal eye movements reduce source-monitoring errors in addition to improving how many items people can remember, Parker and his colleagues presented 102 college students with recordings of a male voice reading aloud 20 lists of 15 words.
Some of the lists converged around a "lure" word that wasn't presented.
For example, subjects might have heard words that included "thread," "eye," "sewing" and "sharp" — all of which converge around the word "needle," even though "needle" was never said.
After the subjects heard all of the lists, a third of them followed a computer prompt that initiated side-to-side eye movements for 30 seconds.
Another third did the same with up-to-down eye movements, and the final third did nothing.
Then the subjects were handed a list of words and asked to pick out the ones they had just heard.
Those who chose the unspoken "lure" words were making source-monitoring errors because they couldn't distinguish having heard the words from having thought the words themselves.
The researchers found that the people who performed the horizontal eye movements correctly remembered, on average, more than 10 percent more words, and falsely recognized about 15 percent fewer "lure" words than the people who performed vertical eye movements or no movements at all.
"The movements could be helping people identify the true source of their memories," said Stephen Christman, a psychologist at the University of Toledo, who was not involved in the study, published in the April issue of Brain and Cognition.
Eye movements and recall
Christman's research has independently shown that such eye movements improve recall memory.
Christman said that he first came up with the idea to look at the effects of eye movements on memory after learning that leftward eye movements activate the right brain hemisphere and that rightward movements activate the left hemisphere.
He thought that horizontal eye movements might, therefore, improve memory by helping the hemispheres interact.
But Parker notes that the proposed mechanism linking eye movement to memory is still somewhat speculative and that more research will be needed to understand how and why eye movements affect memory.
Christman said he has received many letters from people wondering whether horizontal eye movements could help them in their everyday lives.
"Let's say you're leaving a mall after a long day shopping and you realize, 'Oh God, I can't remember where I parked my car,'" he said. "Would it help you if you stood there in the parking lot and just wiggled your eyes back and forth for 30 seconds?"
He's not sure, he said — but it might be worth a shot.
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