Too Much Self-control Can Overwhelm Brain

It may be admirable to try to quit smoking, cut out junk food and hit the gym all at the same time, but new research from the University of Toronto suggests that success is more likely when people tackle one bad habit at a time. Too much self-control, the researchers say, may deplete the brain.

In an innovative brain study that explored the limits of self-control, Michael Inzlicht, an associate professor of psychology at the University of Toronto Scarborough, asked students to watch a disturbing movie. Half were told to suppress their emotions as they watched the film; the other half were free to express their feelings. All participants then performed a well-known test of self-control called the Stroop task. This test requires the taker to look at the words red and green, written in either a red or green font. They then are asked to identify the word's colour, and not the word itself. Doing so requires a form of self-control. All the while, electrodes measured participants' brain wave activity.On average, the students who had used self-control to suppress their emotions during the movie performed poorly on the second task that tested self-control. Self-control, in other words, is limited. Most interesting, the researchers also noted their participants showed weak activity in the anterior cingulate cortex - a portion of the brain that plays a watchtower role, alerting us when our goals are not being met."Self-control is a limited resource that depletes very quickly," said Inzlicht. "Students who were required to suppress their emotions during the film had limited self-control to draw on for the next task. This shows us that if you set too many goals that require self-control, you overwhelm the brain and this can be a recipe for disaster."The study appears in the November issue of Psychological Science.(Source: Psychological Science : University of Toronto : January 2008)