Probing Question: Why do we forget?

"Ithink we should cut our brains some slack," says Dawn Blasko, grinning. "Our brains do an enormous amount of processing. In fact, they work like very effective computers, so effective that we only notice the few things that we forget. We never give our brains credit for the vast amount of material that we do, in fact, remember."

That said, it's still frustrating when we lose track of the car keys for the umpteenth time, or forget the name of a favorite restaurant. So, what accounts for these run-of-the-mill lapses?

head with brain with key
James Collins

Blasko, associate professor of psychology at Penn State Erie, and colleague Michael Hall of the University of Nevada, Las Vegas may have recently uncovered a clue to the mechanics of memory failure. They devised an experiment that overloaded their subjects' brains with information and then tried to pinpoint what caused the memory system to breakdown. By taxing the brain's ability to retain information, they hoped to discover the relationship of working memory to attention, as well as the differences in "working memory" for each individual.

"It's clear that we can't focus on everything in our environment at once," explains Blasko. "We are quickly overburdened. What we call working memory is the information we are actively thinking about and processing at any given moment."

"According to one theory," Blasko adds, "working memory is closely related to the ability to allocate our attention to the most important things going on. For example, if you are driving down a highway with your children arguing in the back seat, your brain will give priority to the most important thing happening—namely, navigating the busy road in front of you—and ignore less important information like the sounds of bickering kids."

In their experiment, Blasko and Hall asked subjects to retain information involving musical timbre. (Musical timbre is the quality of a musical note that distinguishes different types of musical instruments.)

Each test subject listened through headphones while the researchers played recorded notes from a violin and clarinet. Sometimes participants heard the same instrument in both ears and sometimes they heard different instruments in each ear. Participants were then asked to focus on the instrument presented to one ear while ignoring the other. Essentially, the test subjects attempted to ignore the irrelevant tones while listening for the specified ones.

Explains Blasko, "This experiment challenged the subjects to sort out conflicting information. What it showed us is that people tend to fall into two groups. Those with high working memory are characterized by their ability to disregard extraneous information and focus single-mindedly on one objective, while those with low working memory are less able to block out unrelated input."

People with better focus, Blasko suggests, do better at the critical task of initially processing information. "If you forget something, it's because you either never really learned it in the first place, or because you learned it for a brief period of time and then forgot it," she says. "But if you really encode the information, it has been stored in your brain and you are more likely to recall it."

The brain also has an override system that "trashes" knowledge they deem outdated, says Blasko. For example, if while we are processing new information pertaining to an existing memory, important new details are revealed, our brains tend to retain only the information it deems most vital.

So the next time you lose your keys, racking your brain to retrace your steps around the house might not help. As Dawn Blasko puts it, "If you never really learned it, don't expect yourself to remember it."

Dawn G. Blasko, Ph.D., is associate professor of psychology at Penn State Erie, The Behrend College. She can be reached at dgb6@psu.edu.

Last Updated August 15, 2005