A key purpose for memory isn’t to just remember the past, but to be able to imagine the future. Shirley Wang reports on Lunch Break. Photo: AP.
Memory allows for a kind of mental time travel, a way for us to picture not just the past but also a version of the future, according to a growing body of research.
The studies suggest that the purpose of memory is far more extensive than simply helping us store and recall information about what has already happened.
Researchers from University College London and Harvard University have made strides charting how memory helps us draw a mental sketch of someone’s personality and imagine how that person might behave in a future social situation. They detailed their latest findings in work published in the journal Cerebral Cortex last week.
What the scientists showed could have implications not just for those who suffer memory loss, like the elderly, but young adults and their ability to plan and socialize. The researchers are also following up what they’ve found by trying to see whether the ability to recall past events may be related to creativity and imagination.
The body of work is “broadening out our view of how we use memory,” says Daniel Schacter, a psychology professor at Harvard.
This ability to imagine or anticipate what may come is important to our ability to plan and problem-solve and helps us make better decisions in social situations. The researchers also hope to uncover new ways of improving human memory.
“Using past experiences to anticipate possible future happenings” lets people weigh approaches to a coming situation without needing to try out the actual behaviors, Dr. Schacter says.
Little is known about why some people might naturally have better abilities to recall experiences or imagine future ones.
Many techniques purported to improve memory or delay cognitive decline, like word games or brain teasers, are focused on working memory, the information we hold in our head at any time. There is mixed evidence about whether they do more than improve the ability to complete a specific task.
Dr. Schacter’s group is focused on a targeted intervention for recalling past experiences, known as episodic memory, and increasing recall of details, not on improving overall memory. The initial experiment is expected to be completed this summer.
Talking to amnesiacs first hinted to researchers that recalling past experiences might be crucial for mental time travel. Along with memory loss, the patients appeared to struggle with planning.
For example, when patient K.C., whom Dr. Schacter and his graduate-school adviser, Endel Tulving, observed in the 1980s, was asked what he would do the next day, he couldn’t come up with specifics. He might say something like, “I think I’ll have breakfast,” but failed to provide any details about what he might have or where he would go, according to Dr. Schacter.
In 2007, Demis Hassabis, a research fellow at the Gatsby Computational Neuroscience Unit at University College London, and his colleagues published a study in the Proceedings of the National Academy of Sciences showing in five amnesiac patients an impoverished ability to imagine and describe future events. The finding generated much excitement in the field and has spurred more research.
Scientists have conducted many studies in the lab since showing that young, healthy adults are much better at imagining future scenarios than older people whose memories have deteriorated. Schizophrenics, who are known to have problems with memory recall, also have trouble imagining the future.
In the studies by Dr. Schacter and his colleagues, when subjects in their early-to-mid 70s were asked about past experiences or future ones, they tended to provide fewer details about people and exactly what happened. Instead, they provided more commentary and reflection, Dr. Schacter says.
For instance, when young people were asked about a shopping trip, they would say who was there and what the store looked like. Older people would say they were interested in buying a vase and why vases are nice to have in the house.
Brain-imaging studies have demonstrated that when people are asked to imagine the future as they recall past experiences, many of the same regions of the brain—the hippocampus and the medial prefrontal cortex—show increased activity. These are also the regions that tend to show changes in aging.
The capacity to come up with detailed simulations appears to have many uses. It contributes to planning by modeling different possibilities without committing to them. Running through a number of scenarios hopefully leads us to a better option.
Researchers at the University of California, Los Angeles found that students who engaged in detailed simulation of studying for a test—imagining all the steps involved in studying—ended up doing better on the exam than those who simply imagined doing well.
Memory also appears to play a role in imagining what someone else might be feeling, known as theory of mind, which is helpful in deciding how to behave in unfamiliar social situations, such as going to a party with a new group of friends or starting a job. People with autism, a condition characterized in part by poor social skills, tend to have poor episodic memory and also poor ability to anticipate others’ reactions or emotions.
Little is known, however, about exactly how the brain works when it is trying to imagine what is going on in someone else’s head. Dr. Hassabis, Dr. Schacter and collaborators delved into this question in their new study, in which they scanned the brains of 19 healthy adults with an average age of 21. During the scans, the doctors asked them to imagine four short scenes involving imaginary people.
First, participants were given photos and 12 statements profiling each of the four characters. Each possessed a different level of extroversion and friendliness.
After spending time familiarizing themselves with the made-up profiles, participants were asked to imagine each of the different personas in situations. For instance: How would they react if a stranger spilled a drink on them?
The researchers found that the ability to spot the different personality traits was encoded in distinct brain regions. This meant they were able to figure out which of the four profiles the participant was thinking about just by looking at what part of the brain showed greater activation when a participant was imagining a scene.
It’s unlikely that the episodic-memory system is the only brain process important for imagining future events, but it appears that a broader framework for autobiographical information, which includes episodic memory, is used to organize the events, according to Arnaud D’Argembeau, a researcher at the University of Liège in Belgium. His work has shown that having knowledge of one’s personal goals—for which memory is also necessary—appears to be another factor in helping with imagining future events.
The capacity to simulate events in one’s head also carries potential downsides. It can lead to trouble if we don’t anticipate all the things that might happen or become overconfident that we have figured out what is going to happen.
Being worse at seeing future outcomes, especially negative outcomes, may contribute to decreases in elderly people’s ability to plan or to realize that someone might be trying to take advantage of them. “It gives you a different lens through which to approach aging,” Dr. Schacter says.