BioEd Online

When attempting to master a task, sometimes it's best not to try too hard. Researchers have confirmed this folk wisdom, using brain imaging to show that thinking too hard about simple actions interferes with the learning process.

Scientists already knew that consciously trying too hard to learn can cause trouble. The earliest demonstration of this came from a study in 1976, in which college students were asked to memorize strings of letters.

Those who were told from the start that there was a regular pattern within the letters found it harder to discriminate between strings that did or did not contain the pattern. But until now, no one understood why this happened.

Paul Fletcher, a psychiatrist at the University of Cambridge, UK, and his colleagues watched the brain activity of people who were learning without consciously trying (implicit learning) and compared it with activity in people who were putting deliberate effort into mastering the challenge.

Rapid response

The team asked subjects to press one of four buttons, depending which one of four boxes on a screen was highlighted. During the six-minute test, each person was required to pushed roughly 300 buttons, including 18 repetitions of a particular 10-item sequence.

One group of volunteers was asked to try to learn the pattern, and a second group was told to relax and not to worry about finding it. Learning the pattern should help people to respond more quickly, explains Fletcher.

At the end of the test, those who weren't looking for a pattern completed the task with a reaction time that was about 40 milliseconds faster than those who were looking, suggesting that the former had learned the pattern more effectively.

During the test, Fletcher and his colleagues monitored the brain activity of the volunteers with functional magnetic resonance imaging, a technique that tracks blood flow to give an ongoing picture of brain activity. They detected a notable boost in the activity of the right frontal lobe in people who were trying to learn the pattern. Their results are published online in Cerebral Cortex.

Task master

The decision-making abilities of the frontal lobes are normally employed during sophisticated thought or learning. These areas communicate with the egg-shaped thalamus, which acts as a mental 'switchboard', filtering sensory information.

Why would increased frontal lobe activity make it harder to learn the pattern? Fletcher explains that the frontal lobes are valuable in a crisis, when it is necessary to make a quick decision about which course of action to take. But this conscious processing might actually inhibit the automatic learning of simpler tasks, he says.

So should we give our brains a break and stop trying to learn? It depends on the type of task, says Fletcher. For example, people who are learning to ski should try to relax as they go down the slope.

"If you work out every turn in advance it disrupts the processes at the motor level," he says. But when it comes to mastering textbooks, some concentration will still be required.