New pictures from the University of Iowa show what it looks like when a person runs out of patience and loses self-control.

A study by University of Iowa neuroscientist and neuro-marketing expert William Hedgcock confirms previous studies that show self-control is a finite commodity that is depleted by use. Once the pool has dried up, we're less likely to keep our cool the next time we're faced with a situation that requires self-control.

Brain activity when people exert self-control. (Credit: Image courtesy of University of Iowa)

But Hedgcock's study is the first to actually show it happening in the brain using fMRI images that scan people as they perform self-control tasks. The images show the anterior cingulate cortex (ACC) -- the part of the brain that recognizes a situation in which self-control is needed and says, "Heads up, there are multiple responses to this situation and some might not be good" -- fires with equal intensity throughout the task.

However, the dorsolateral prefrontal cortex (DLPFC) -- the part of the brain that manages self-control and says, "I really want to do the dumb thing, but I should overcome that impulse and do the smart thing" -- fires with less intensity after prior exertion of self-control.

This image shows brain activity after people have been engaged in self-control tasks long enough that self-control resources have been depleted. (Credit: Image courtesy of University of Iowa)

He said that loss of activity in the DLPFC might be the person's self-control draining away. The stable activity in the ACC suggests people have no problem recognizing a temptation. Although they keep fighting, they have a harder and harder time not giving in.

Which would explain why someone who works very hard not to take seconds of lasagna at dinner winds up taking two pieces of cake at dessert. The study could also modify previous thinking that considered self-control to be like a muscle. Hedgcock says his images seem to suggest that it's like a pool that can be drained by use then replenished through time in a lower conflict environment, away from temptations that require its use.


Original citation: Hedgcock, W.M., Vohs, K.D., Rao, A.R. (2012). Reducing self-control depletion effects through enhanced sensitivity to implementation: Evidence from fMRI and behavioral studies. Journal of Consumer Psychology, In Press, Corrected Proof, Available online 24 May 2012 DOI: 10.1016/j.jcps.2012.05.008