How the Human Brain Processes Mistakes

The human mind dislikes making mistakes and finds ways to avoid repeating them. New research from the University of Iowa shows that the brain can distinguish between an outcome caused by a human error and one for which the person is not directly responsible in just one second.

The ability to adapt behavior after making a mistake is a key aspect of cognitive control. Realizing a mistake has been made usually causes people to slow down their subsequent actions—a phenomenon known as post-error slowing (PES). It is believed that the brain networks involved in processing errors overlap with those that handle “surprises” not related to errors. This raises the question: does the brain have a special system for processing mistakes?

In this study, researchers wanted to find out whether there are truly unique, error-specific processes that contribute to PES, beyond just general surprise. They conducted an experiment to analyze the brain’s ability to distinguish the cause of an error. Seventy-six young adults were asked to look at a group of arrows and choose the correct direction indicated by a specific arrow. When participants answered correctly (which was almost always, since the task was easy), a triangle appeared on the screen. However, from time to time, other symbols—such as an anchor, frog, or helicopter—would appear instead, even when the answer was correct and a triangle was expected. This was designed to simulate an unexpected outcome.

The researchers measured the brain’s response to standard and “surprise” outcomes at three different intervals: 350, 1700, and 3000 milliseconds. They found that the brain needs about one second (1000 milliseconds) to distinguish between these two types of results. If the brain “noticed” a human error, it remained active for another 2–3 seconds, using this time to process and remember the mistake for the future.

“When it’s related to my own actions and I can do something about it, the brain needs a few seconds to reset the entire cognitive apparatus, the visual and motor systems. It’s as if the brain needs some time to inform the rest of the body, senses, and motor functions: ‘Let’s not do that again,’” explains Jan Wessel, professor of psychology and brain sciences at Iowa and co-author of the study.

At the same time, the researchers measured brain waves using a scalp electroencephalogram (EEG). They observed sustained neural activity that was different in cases of errors.

“Although both errors and unexpected outcomes of correct actions led to similar early neural activity, only errors showed strong, sustained brain activity more than a second after the response. Overall, this suggests that the human brain has real, specific systems that detect the mistakes we make and trigger adaptive responses, such as strategically slowing down current actions.

When a human error occurs, the brain needs extra time to process the mistake and communicate it to the rest of the body to prevent it from happening again.

“The new aspect of this research is that the brain can very quickly determine whether an unwanted outcome was caused by a human error or something else,” says Wessel. “If the brain realizes the cause was a mistake, it will launch additional processes to avoid further errors—something it won’t do if the outcome wasn’t caused by its own actions.”