Predictable Forgetfulness
Just heard it - and gone again: Our memory plays tricks on us every day. Why do we forget names, phone numbers or vocabulary? Was the little gray matter missing the right attitude?
What was Mr.'s phone number again… yes, what was his name? Surely you know this: You only found out the name and telephone number an hour ago - but the information has probably not found its way into the long-term memory. While we still remember some events years later, freshly learned knowledge is often lost. But why does our memory keep failing us?
Previously, brain researchers assumed that events that storm our brain cells during and after the information to be stored affect memory. But what about the events just before that? Do they affect memory performance? Can it be measured and thus predict how well we can remember something?
This is exactly what Leun Otten and her colleagues from University College London tried to do. To do this, the researchers confronted their test subjects with new words that appeared on a screen every four to five seconds. "It sounds like clairvoyance: We can predict whether someone will be able to remember a word before they say it ever seen"
(Leun Otten) The subjects had no idea that their memory was to be tested. Rather, their task was to decide whether the term they were reading represented something living-that is, the meaning of the word was in question-or simply to indicate whether the first and last letters of the word appeared in alphabetical order-that is, to pay attention to the spelling. A few seconds beforehand, a small symbol on the screen indicated which task was due - meaning analysis or spelling.
The test came almost twenty minutes later: The subjects were asked to decide whether they could remember the words shown again. As might be expected, they did so especially when they had previously focused on the meaning of the vocabulary being studied.
It got interesting when the researchers analyzed the brain waves of their test subjects, which they had recorded during the experiment using an electroencephalogram (EEG). In contrast to the popular functional magnetic resonance imaging (fMRI), EEG measurements do not achieve the same spatial resolution, but they can record changes in brain activity within fractions of a second.
And a lot happened here: As soon as the subjects realized that they had to concentrate on the meaning of the word, the areas of the cerebrum below the forehead – where conscious thinking is localized – activated. The better the subjects were able to remember the terms later, the stronger the so-called event-related potentials (ERPs), which lasted only a few milliseconds, appeared beforehand.
"It sounds a bit like clairvoyance, but we can actually predict whether someone will be able to remember a word before they even see it," explains Otten. "Scientists already knew that brain activity changes when memory stores something. But now we have found a brain activity that can be used to predict how well memory will perform in the future."
Our brain seems to prepare itself a few seconds before processing new information. "Try to understand what is written"
(Leun Otten) This assumption is confirmed by a second experiment: Here, the test subjects should always concentrate on the meaning of the words, which they sometimes read and sometimes heard. The negative EKPs – which announced good memory performance – only occurred for the terms to be read. As the researchers suspect, switching the input channel from the ear to the eye simply takes too long for the brain to immediately adjust to a concept to be learned.
"We would like to know which brain regions are involved in this preparation," says Otten. Complementary fMRI studies should answer this question. But the brain researcher can already give schoolchildren, students and all other people who are willing to learn some important advice - namely to think about things instead of stupidly memorizing them: "Try to understand what you have written and don't just pray it out!"
