An error rattles the brain temporarily
A slip-up, a speech error or a missed musical note literally knocks us out of our rhythm and makes us slow down, write Leiden psychologists in the Journal of Neuroscience. ‘Due to an “Oops, a mistake!” reaction, the brain becomes momentarily distracted,’ says Leiden scholar Rudy van den Brink, first author of the article.
Neuroscientists know that activities like walking, talking and making music have a certain rhythm to them, and the brain produces a wave pattern that keeps in step with that rhythm. Thanks to the way the rhythms sync, we perform these tasks quickly and precisely. But sometimes we still make a mistake. ‘It is known that we slow down after a mistake,’ says Van den Brink, PhD candidate in Cognitive Psychology. ‘Sometimes we are conscious of that, sometimes not. We suspected that the slowing down was caused by the fact that after a mistake the brain rhythm momentarily deviates from the rhythm of the activity.’ Together with intern Syanah Wynn, he conducted experiments that confirmed that suspicion. ‘This contributes to our understanding of cognitive control over activities. In the distant future, this could be important for treating disorders where there is somewhat less control, like ADHD.’
Test subjects were assigned a test with a set rhythm. At roughly 1350-millisecond intervals they were visually presented with one of four different letters, flanked by six other letters. Each one of the four target letters had a corresponding button that they had to press, and fast! Van den Brink: ‘The test was tough, because what we were interested in was the effect that the errors would have. So the subjects needed to make a decent number of mistakes.’ He measured the reaction time after each stimulus (letter) and also took an EEG during the task.
As expected, a wave pattern in the EEG emerged that during the test became increasingly synchronised with the rhythm at which the stimuli were appearing. And at the same time the reaction time became shorter. When test subjects pressed the wrong button after a letter, the EEG rhythm got momentarily out of phase with the rhythm of the stimuli. Furthermore, subjects then reacted more slowly to the subsequent letter. The most startling result was that they slowed down more as the brain rhythm deviated more sharply from the rhythm of the stimuli. A separate experiment had shown that test subjects were aware of most of the mistakes.
‘The brain gets distracted by the error, whereby the brain rhythm shifts and gets out of sync with the rhythm of the stimuli. Consequently, it takes more time to process the new stimulus,’ concludes Van den Brink. A different cause for the slow-down occurring after an error had been known for some time. A test subject (unconsciously) feels compelled to work more precisely, a strategic adjustment that requires a longer reaction time. ‘Something was already known about the underlying mechanism to that. The mechanism of the distracting “oops” reaction is new.’
(12 August 2014)
Brink, R.L. van den, S.C. Wynn & S. Nieuwenhuis, 2014. Post-error slowing as a consequence of disturbed low-frequency oscillatory phase entrainment. The Journal of Neuroscience 34: 11096 -11105.