The Importance of Forgetting: Why a Bad Memory is a Good Memory

I wish my memory was like a computer’s. I’ve lost car keys, a cellphone, a driver’s license and on the eve of an overseas trip, a passport; wouldn’t things be easier if I could effortlessly organize millions of pieces of information and retrieve them like with a mental Google search?

Alas, my memory – and yours – evolved according to different plans. Instead of neatly storing pieces of information into a neural bookshelf, memory organizes itself more like a web where experiences are stored contextually and in relation to one another. “An item is stored in relation to other items,” neuroscientist Dean Buonomano explains, “and its meaning is derived from the items to which it is associated.” This is why, for instance, thinking about “Africa,” “Animal,” “Stripes,” and “Black and White” automatically pops “Zebra” into your conscious mind. And as Proust famously illustrated in his lengthy classic Remembrance of Things Past, a single recognized combination of taste and smell can trigger an avalanche of memories.

At its extreme, our imperfect memory is sometimes the difference between life and death. About 6 percent of skydiving deaths are caused by forgetting to tug on the rip-chord and scuba divers too often forget to check their oxygen cage. It is also responsible for numerous false eye-witness accounts, including that of rape victim Jennifer Thompson, which landed the innocent Ronald Cotton in jail for 11 years. In addition, our tendency to foolishly believe that so-called “flashbulb” memories are accurate isn’t very impressive.

Indeed, our memory is far from perfect. However, is this a bad thing? A recent Scientific American Mind article by Ingrid Wickelgren suggests that for all its setbacks memory is a fairly well oiled cognitive capacity. She explains:

For most people, the concept of forgetting conjures up lost car keys, missed appointments and poor scores on exams. Worse, it augurs dementia. Psychologists traditionally shared this view, and most of them studied memory with an eye toward closing the cracks through which knowledge can slip… An early challenge to that downbeat view of forgetting emerged in 1970, when psychologist Robert A. Bjork, now at the University of California at Los Angeles, reported that instructions to forget some learned items could enhance memory for others. Forgetting is therefore not a sign of an inferior intellect—but quite the opposite. The purpose of forgetting, he wrote, is to prevent thoughts no longer needed from interfering with the handling of current information—akin to ridding your home of extraneous objects so that you can find what you need.

Memory is much more efficient in this light. Because 99 percent of our experiences are fairly uneventful and meaningless, the mind does a good job of only holding onto the important stuff while discarding the rest. Sure there are obvious downsides to this, but there are upsides also. Wickelgren goes onto explain the importance of forgetting:

In a study published in 2001 [Michael C.] Anderson and his student Collin Green… gave 32 college students what they called a think/no-think task. The students learned 40 word pairs such as ordeal-roach, with the first word serving as a cue for the second. Next they presented the cues and asked participants either to think about and say the word that went with it or to suppress (not think about) the associated word. Suppression seemed to work. The students even recalled fewer of the suppressed word associations than the “baseline” words—ones they learned but neither practiced nor inhibited…

[But] forgetting does not come easily to everyone…. This skill, or lack of it, has ripple effects on personality. If you cannot shake negative memories, for example, you might be easily sucked into a bad mood. Although the inability to forget does not cause depression, research shows that depressed patients have difficulty putting aside dark thoughts. In one experiment, published in 2003, psychologist Paula T. Hertel of Trinity University in San Antonio and Melissa Gerstle, now at the Texas Children’s Hospital and Baylor College of Medicine, found that depressed students recalled many more words they had practiced suppressing than other students did. The students who had the most trouble forgetting scored the highest on measures of rumination—which is the tendency to dwell on a concern—and the frequency of unwanted thoughts.

Those who do not suffer from depression, on the other hand, benefit from the brain’s natural tendency to remember the good and forget the bad. This cognitive advantage influences us to remember a spoiled camping trip as a “great time” with friends or a disastrous trip to Disney World as a “good bonding experience” for the family. It also seems to cause women to only remember the good parts of childbirth – the end; a nice evolutionary quark that influences them to continue reproducing. Perhaps most importantly, the brain’s automatic ability to forget the bad helps people get over most personal losses, emotional trauma and bad breakups. As Jim Carrey’s character Joel Barish illustrates in the movie Eternal Sunshine of the Spotless Mind, people will go a long way to forget certain experiences if they cannot do so naturally. With this in mind, I’m glad my memory is not like a computer.

If there is a bottom line it is this. The purpose of human memory is not to store information but to organize information so we can understand and predict the world. The downsides of this abound, but I say evolution did a pretty good job. Car keys, cell phones, licenses and passports weren’t very important over the last few million years when our ancestors were evolving, after all.