Too Much Thinking Harms Mental Performance, Researchers Say

Rebecca Lewis August 13, 2013

It’s true that paying attention is critical to brain health. But at some points, it may actually impede mental performance, suggests a new study.

Researchers at UC Santa Barbara found that paying full attention and trying hard could be detrimental to human performance. According to them, there are two kinds of memory – the implicit and explicit. The first one is a form of long-term memory that requires no conscious thought and is expressed by means of other than words. The second type is a kind of long-term memory that is formed consciously and can be expressed in words. In their study, researchers considered these areas of function both behaviourally and in the brain.

“A lot of people think the reason we’re human is because we have the most advanced prefrontal cortex,” said Taraz Lee, Ph.D., lead author of the study. Previous studies suggest that taxing explicit memory resources. Their findings show that implicit perceptual memory can aid performance on recognition tests.

In the current study, Lee and his team investigated whether the effects of the attentional control processes associated with explicit memory could directly interfere with implicit memory. Using the continuous theta-burst transcranial magnetic stimulation (TMS) technology, they temporarily disrupt the function of dorsolateral and ventrolateral cortex– two different parts of the prefrontal cortex. The prefrontal cortex is the part of the brain primarily involved in planning, executive function, and working memory. The purpose of disrupting the function of the said brain regions is to test whether explicit memory processing exerts control over sensory resources and could therefore interfere with the implicit memory processes.

Then, participants were shown a series of kaleidoscopic images for about a minute. After a minute of break, they went through memory tests in which they had to distinguish the images they have previously seen from the new ones.

After the activity, the researchers asked the participants if they had a vague impression or were simply blindly guessing. According to Lee, the subjects did better when they were guessing.

Their study sheds light on why paying attention can be a distraction and affect performance outcomes. “If we ramped down activity in the dorsolateral prefrontal cortex, people remembered the images better,” said Lee. “They would shift from saying that they could remember a lot of rich details about the image to being vaguely familiar with the images,” Lee said. “It didn’t actually make them better at the task.”

In future research, Lee would like to study why people who are highly incentivized to do well often succumb to pressure and how the prefrontal cortex and these attentional processes interfere with performance. “If we can figure out the ways in which activity in this part of the brain hurts you, then this also informs how your brain works and can give us some clues to what’s actually going on.”

Their work was published in the Journal of Neuroscience.

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Thinking Too Much Can be Detrimental to Human Performance