Back to the Future

Memory has nothing to do with preserving the past.

Posted Apr 21, 2015

“Where were you at 8:30 in the evening on November 14?” the detective asks. And he really expects you to answer.

You search through your memory and come up with nothing. “What day of the week was it?” you ask.

“Friday.”

“Then I must have been bowling,” you reply. “I always go bowling on Friday nights.”

But still you can’t remember any events from that evening, and the detective senses your uncertainty.

“Are you absolutely sure?” the detective demands.

Public Domain via Wikimedia Commons
Where were you on the evening of November 14?
Source: Public Domain via Wikimedia Commons

We think our memories work like video cameras, faithfully recording the episodes of our lives. When we can’t remember an event—or if our recollection doesn’t match those of others who were there—we feel our memory has somehow betrayed us. And yet there’s nothing wrong with our memories, only our expectations about them.

We think we can accurately recall the events of our lives. In reality, our remembrances of things past are like TV docudramas, loosely based on facts but mostly works of fiction.

This is because memory has nothing to do with recording the past. After all, the past is gone and there’s nothing we can do about it. All we can do is to keep moving forward, minding our step as we go. And that’s the purpose of memory—to help us predict the future.

Our brains don’t store everything that happens to us, only those events that may have future relevance. That’s why most evenings, you pull into your driveway with little recollection of your commute home. But if you’d nearly had an accident, or almost hit a deer, or gotten pulled over for speeding, that memory will be seared into your brain. And after that, you’ll automatically slow down each time you approach that “dangerous” location.

Pattern-detecting brains enable animals to learn about the world so they can interact with it. (Plants, by the way, don’t have brains because they don’t move.) For a thought-provoking take on “The Real Reason for Brains,” see this TED Talk by neuroscientist Daniel Wolpert.

We humans, with our supersized brains, detect all sorts of patterns, even those that aren’t there. We see a silhouette of Elvis on a grilled cheese sandwich, or a figure of the Virgin Mary on a mud-splattered wall. Illusions like these are the price we pay for having such powerful brains.

Polihale / Wikipedia
The Clearwater Virgin: Miraculous apparition or water discoloration?
Source: Polihale / Wikipedia

We’re so good at detecting patterns, in fact, that we even do it for fun. That’s what the joy of music is all about. Growing up, we internalize the rules of music for our culture. When we listen to a piece, our brains look for patterns in the musical structure and try to predict what’s coming next. If our expectations are met, we’re satisfied. And if our expectations are exceeded, as for example when the piece ends in an unexpectedly clever way, we’re thrilled.

Our pattern-detecting brains play an important role in language as well. Human babies use their pattern detectors to decode the language that’s spoken to them. And even as adults, we’re constantly predicting what’s coming next in a conversation. That’s why we’re so often able to finish each other’s sentences.

But constantly generating predictions can also lead us astray. Consider the following sentence:

While Mary bathed her baby played on the floor.

A well-placed comma in writing—or pause in speech—will disambiguate this “garden path” sentence, but we’re led astray without it. We expect her baby to be the object of bathed, but then the rest of the sentence doesn’t make sense. Our expectation was violated, and now we’re confused about whether it was Mary or the baby who took a bath.

We depend on memory whenever we interact with the objects of the natural world or with the people of our social circles. Memory is our storehouse of patterns that we glean as we go through life. We then rely on these patterns to make predictions about how others—and we ourselves—will act.

You have no idea where you were on the evening of November 14. But it was a Friday, your bowling night—a pattern. And so you must have been bowling—a prediction. And thus our memories take us back, to lead us into the future.

Terabass / Wikimedia Commons
Like a refitted Delorean, your memory takes you back to the future.
Source: Terabass / Wikimedia Commons

Reference

Salimpoor, V. N. et al. (2015). Predictions and the brain: how musical sounds become rewarding. Trends in Cognitive Science, 19, 86-91.

David Ludden is the author of The Psychology of Language: An Integrated Approach (SAGE Publications).