Why mistakes slow us down?

Taking more time to make decisions after a mistake arises from a mixture of adaptive neural mechanisms that improve the accuracy and reduce maladaptive mechanisms, according to a study.

"Our research reveals that a combination of changes in the brain slow us down after mistakes," said Braden Purcell, a New York University researcher and coauthor of the study.

"One gathers more information for the decision to prevent repeating the same mistake again. A second change reduces the quality of evidence we obtain, which decreases the likelihood we will make an accurate choice," Purcell added.

It has been long established that humans often slow down after mistakes, a phenomenon called post-error slowing (PES). Less clear, however, are the neurological processes that occur under PES.

The NYU researchers conducted a series of experiments involving monkeys and humans to address this question.

Both watched a field of noisy moving dots on a computer screen and reported their decision about the net direction of motion with their gaze.

The researchers controlled the difficulty of each decision with the proportion of dots that moved together in a single direction -- for instance, a large proportion of dots moving to the right provided very strong evidence for a rightward choice, but a small proportion provided only weak evidence.

Humans and monkeys showed strikingly similar behaviour. After errors, both slowed down the decision-making process, but the pattern of slowing depended on the difficulty of the decision.

Slowing was maximum for more difficult decisions, suggesting longer accumulation of information. However, the overall accuracy of their choices did not change, indicating the quality of accumulated sensory information was lower.

The study potentially offer insights into afflictions that impair judgments, such as Alzheimer's disease and Attention Deficit Hyperactivity Disorder (ADHD).

The study findings were published recently in the journal Neuron.