In other words, instead of reading and re-reading a list of vocabulary words, you should read it once and then test yourself repeatedly.
The same strategy works for pretty much anything you’re hoping to commit to memory, and there’s a growing body of research behind it. Psychologists call this phenomenon the “testing effect.”
A 2003 study, cited in a meta-analysis by Henry L. Roediger, III and Jeffrey D. Karpicke, highlights the power of testing for making information stick. In the study, researchers led by Mark Wheeler had participants either review a list of 40 words five times or review it once and take four recall tests. Then they took a recall test either five minutes or one week later.
Results showed that participants who’d read the word list five times performed much better on the recall test five minutes later. But participants who’d read the test just once and been tested performed better on the test one week later. In other words, testing helped boost the participants’ long-term memory.
More recent research suggests that combining testing with immediate feedback (finding out whether you answered right or wrong) is more effective, and can even boost memory right after the information is learned.
In a 2014 study led by Carola Wiklund-Hörnqvist, 83 students in an undergraduate psychology course studied a series of psychological concepts for four minutes. Half the participants continued to study these facts while each fact was presented on a computer screen for 15 seconds.
The other half took six tests in which they had to come up with the concept described on the screen. For example, if they saw “the improvement in retention of information presented at the beginning of a list,” they would have to type in “primacy effect.” Then they would see the correct answer.
At the conclusion of the learning period, all participants took a test in which they were presented with a fact and required to type in the corresponding concept. They took the same test 18 days and five weeks later.
Participants who had been tested performed better on all three tests.
Taken together, these studies suggest that the most efficient strategy for remembering something — whether you’re learning a new language or studying for a science exam — is simply to practice recalling it. It’s probably a lot more effective than trying to drill the facts into your head by staring at them for an hour.