Intuition, Memory Help Us Keep Track of Numbers

by Scott P. Edwards

November, 2008

For many of us, numbers consume our daily lives: phone numbers, personal identification numbers, access codes, dates, Social Security numbers. How does our brain remember all these numbers as we continually encounter more? Scientists think our ability to remember numbers may to have to do with an innate “numbers sense,” as well as simple memorization.

Stanislas Dehaene, director of the Inserm-CEA Cognitive Neuroimaging Unit in France, says humans are born with a numbers sense, related more to basic calculations and estimates than to recall.

“All infants seem to have a basic number sense,” he says. “Our research suggests that higher mathematical abilities are founded upon basic intuitions of space, time and number, which are largely inherited from our evolutionary past.”

Recent research published in Nature by scientists at Johns Hopkins University has established a link between this primitive numbers sense and math performance in school, which may or may not relate to how well people remember numbers. Lead author Justin Halberda, a Johns Hopkins psychologist, says it remains to be determined whether this numbers sense acuity affects later math learning or vice versa.

Although mathematicians and others who work with numbers on a regular basis may have an advantage because of their constant exposure to numbers, Richard Roche, a neuroscientist at the National University of Ireland who specializes in the neurocognitive mechanisms underlying memory consolidation, says an individual’s recollection of important numbers may have more to do with rote learning than with any type of numbers sense.

“While some people do seem to be naturally more comfortable with numbers in general, it shouldn’t really matter what the information is in order to remember it,” he says. “It may be the case that it’s not as easy to make meaningful associations with numbers as it is with other information, so numbers may seem more difficult to recall.”

Two years ago, Roche and Jonathan McNulty of University College Dublin found that older adults who engaged in an intensive period of rote learning followed by an equally long rest period exhibited improved memory and verbal recall.

“Unlike other studies on memory involving specific regimes, memorizing is an everyday activity that anyone can undertake,” says Roche.

In rote learning, we repeat information until we can remember it. The principle is that, every time a person encounters new information—a phone number, for example—the information activates a neural circuit in the brain called the memory trace.

The repetition of this information, Roche says, reactivates the memory trace. Each time it is repeated, the trace representing the new number is thought to grow stronger.

“So, after rote learning, the material that was repeated over and over will have a strong memory trace, and when you try to recall a number, you should be able to remember it because that brain circuit is more likely to be activated,” says Roche.

Context also plays a significant role in our ability to recall numbers. In the 1970s, British psychologist Alan Baddeley conducted a study showing that people are more likely to recall information if they are tested on it in the same context or environment in which they learned it. Study participants were given a list of words to learn. Some people learned these words on land, while others did so underwater in scuba gear. Words learned on land were best recalled on land, and vice versa. When the context was different, recall was poorer.

Other studies have shown that being back in the original context can help with recall. “So, in terms of an ATM number, people sometimes panic that they’ve forgotten their number, but once they’re standing in front of the ATM, the number suddenly comes back to them,” says Roche.

Roche suggests that our ability to recall numbers may be strengthened by engaging in rote learning activities.

“It seems as though the memory system might act a little like a muscle,” he says, “so using the memory apparatus in the brain regularly may keep these regions in good health and more effective at retaining memories.”