“Put on your thinking cap” could soon be more than just a colloquialism. Psychologists at Vanderbilt University have developed a “cap” that caused subjects to make fewer errors when learning a novel task.
Robert Reinhart and Geoffrey Woodman, coauthors of the study, were interested in the negative voltage produced in our brain’s medial-frontal cortex when we make errors. They hypothesized that we learn from errors in response to this electric impulse. Animal trials indicated that it was possible to regulate these electrophysiological impulses so that they were stronger or weaker in conjunction with a subject’s errors. The technique had never been tested with human subjects before, though.
In their study, Reinhart and Woodman fitted subjects with an elastic headband that held two electrodes in place on subjects’ heads. One electrode was placed on the crown of the head, and the other lay on the subject’s cheek. The electrodes delivered a very gentle electric current through the subjects’ skin and skull and into their brains. (Don’t worry, it didn’t hurt! Subjects reported that the sensation felt like tingling or tickling.) Each subject was randomly assigned to receive stimulation according to one of three conditions: 1) a current running anodally, from crown to cheek, 2) a current running cathodally, in the opposite direction, from cheek to crown, and 3) no current at all, but a sensation designed to simulate the feeling of one. Subjects weren’t able to tell which of the three stimulations they were receiving.
After 20 minutes of stimulation, subjects began a learning task. Through trial and error, they had to figure out which buttons on a game controller corresponded with colors displayed on a screen. Since they had to make decisions very quickly, they made plenty of errors, resulting in lots of opportunities for their medial-cortexes to fire.
During the learning task, Reinhart and Woodman monitored the electrical activity in the subjects’ brains. The results of this monitoring, and of the subjects’ learning outcomes, demonstrated a clear trend: 75% of the subjects who had received anodal stimulation (crown to cheek) produced much more negative voltage with each error than the cathodal (cheek to crown) group; they demonstrated much smaller spikes in medial-cortex negative voltage when they answered incorrectly. Strikingly, negative voltage spikes were strongly associated with better performance on the task. The anodal group mastered the matching game more quickly, while the cathodal group made more errors and required more time to learn the task.
Reinhart describes the results as “extraordinary” since an external stimulus was able to make subjects more cautious, less error-prone, and more adaptable. It should be noted that the error rates between the two groups differed very little, only four percent. However, Woodman observes that this rate is far better than rates found in studies of pharmaceuticals or psychological therapy. The effects of the electrical stimulation transferred to other tasks and lasted an average of five hours.
These “thinking caps” certainly have implications for improving learning. Further, they could prove beneficial for the treatment of conditions which are associated with performance-monitoring deficits, like ADHD and schizophrenia.
The full study can be found in the Journal of Neuroscience.
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