The best way to retain memories may depend on the content

New experiments by psychologists at the University of Pittsburgh and Temple University suggest varying what we study and spacing out our learning over time can both be helpful for retaining memories — it just depends on what we’re trying to remember. The work provides new insight into how we learn and remember our real-world experiences.

“Lots of prior research has shown that learning and memory benefit from spacing study sessions out,” said Benjamin Rottman, an associate professor of psychology and director of the Causal Learning and Decision-Making Lab at Pitt. “For example, if you cram the night before a test, you might remember the information the next day for the test, but you will probably forget it fairly soon. In contrast, if you study the material on different days leading up to the test, you will be more likely to recall it for a longer period of time.”

This “spacing effect” is one of the most replicated findings in psychological research, but much of that work has been predicated on the idea that what you are trying to learn repeats identically each time. Yet that is rarely the case in real life, when some features of our experiences may stay the same while others are likely to change.

For example, imagine repeat trips to your local coffee shop. You might see the same tables, seats and decorations, but a new barista may be serving you. It’s not clear that the spacing effect would work the same way in the face of such changes.

In two experiments, the researchers asked participants to repeatedly study pairs of items and scenes that were either identical on each repetition or where the item stayed the same, but the scene changed each time.

One of the experiments asked participants to learn these pairings and then test their memory via their smartphones — an unusual approach for learning and memory research. This enabled researchers to ask participants to learn pairs at various times of the day across 24 hours, more accurately representing how people actually learn information than in prior lab experiments.

In the second experiment, researchers collected data online in a single session. The team published their results in the March 12 online edition of the Proceedings of the National Academy of Sciences.

The setup allowed the team to study the effects of memorizing both across different timescales and the content of what’s being memorized, explained Emily Cowan, lead author on the paper and a postdoctoral fellow in Temple’s Adaptive Memory Lab. “With this, we were able to ask how memory is impacted both by what is being learned — whether that is an exact repetition or instead, contains variations or changes — as well as when it is learned over repeated study opportunities.”

As in prior experiments, researchers found that spaced learning helped participants remember the items. But they also found the participants’ memory was better for the items that had been paired with different scenes compared to items shown with the same scene repeatedly. For example, if you want to remember a new person’s name, repeating the name but associating it with different information about the person can be helpful.

On the other hand, Rottman said, stability appeared to aid the type of memory that pairs items and scenes. “Spacing only benefited memory for the pairs that were repeated exactly, and only if there were pretty long gaps, hours to days, between study opportunities,” he said. “For example, if you are trying to remember the new person’s name and something about them, like their favorite food, it is more helpful to repeat that same exact name-food pairing multiple times with spacing between each.”

The Pitt-Temple experiments represent basic memory research, and so the research may not necessarily apply to some types of real-world memorizing tasks. “Because of how nuanced memory is, it is hard to provide clear advice for things like studying for a test because the sort of material can be so different,” Rottman said. “But in theory our findings should be broadly relevant to different sorts of tasks, like remembering someone’s name and things about them, studying for a test and learning new vocabulary in a foreign language.”

Cowan continued: “Our work suggests that both variability and spacing may present methods to improve our memory for isolated features and associative information, respectively, raising important applications for future research, education and our everyday lives.”

In addition to Cowan and Rottman, study investigators included Vishnu “Deepu” Murty, principal investigator of Temple’s Adaptive Memory Lab, and Yiwen Zhang, a graduate student in cognitive psychology at Pitt.

— Bruce Steele, photography by Tom Altany