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When our vices get the better of us

What happens in the brain when we just can’t say no?

Oct. 11, 2007
Courtesy Association for Psychological Science
and World Science staff

Drug abuse, crime and obes­ity are but a few of the prob­lems mod­ern so­ci­e­ty faces, but they all have one thing in com­mon: peo­ple’s fail­ure to con­trol them­selves in the face of tempta­t­ion. While the abil­ity to re­strain our im­pulses is a de­fin­ing fea­ture of the hu­man an­i­mal, its fail­ure is one of so­ci­e­ty’s cen­tral prob­lems. So why do we so of­ten lack this cru­cial abil­ity? 

The anterior cingulate cortex (ACC), marked in red. This brain area is crucial to self-control, researchers say.
As hu­mans, we have lim­it­ed re­sources to con­trol our­selves, re­search­ers say; all acts of con­trol draw from one source. So when us­ing this re­source in one do­main, such as di­et­ing, we’re more likely to run out of it in an­oth­er do­main, like stu­dy­ing hard. 

Once these re­sources run out, our self-con­trol abil­ity is di­min­ished, ac­cord­ing to sci­ent­ists. The di­et­er is more likely to eat choc­o­late, the stu­dent to watch TV, and the pol­i­ti­cian to ac­cept a bribe.

In a re­cent stu­dy, Mi­chael In­zlicht of the Un­ivers­ity of To­ron­to Scar­bor­ough and col­league Jen­ni­fer N. Gut­sell of­fer an ac­count of what’s hap­pen­ing in the brain when our vices get the bet­ter of us.

In­zlicht and Gut­sell asked par­ti­ci­pants to sup­press their emo­tions while watch­ing an up­set­ting mov­ie. The idea was to de­plete their re­sources for self-con­trol. The par­ti­ci­pants re­ported their abil­ity to sup­press their feel­ings on a scale from one to nine. Then, they com­plet­ed a Stroop task, which in­volves nam­ing the col­or of printed words (i.e. say­ing red when read­ing the word “green” writ­ten in red), yet an­oth­er task that re­quires self-con­trol.

The re­search­ers found that those who sup­pressed their emo­tions per­formed worse on the task, in­di­cat­ing that they had used up their self-con­trol re­sources while hold­ing back their tears dur­ing the film. 

An electroencephalogram (EEG), a recording of electrical activity in the brain, con­firmed the re­sults, they said. Nor­mal­ly, when a per­son de­vi­ates from their goals (in this case, want­ing to read the word, not the col­or of the font), in­creased ac­ti­vity oc­curs in a part of the brain called the an­te­ri­or cin­gu­late cor­tex, which alerts the per­son that they are off-track. The re­search­ers found weaker ac­ti­vity in this brain re­gion dur­ing the Stroop task in those who had sup­pressed their feel­ings. In oth­er words, af­ter en­gag­ing in one act of self-con­trol this brain sys­tem seems to fail dur­ing the next act, they said. 

The find­ings, which ap­pear in the No­vem­ber is­sue of the re­search jour­nal Psy­cho­log­i­cal Sci­ence, have im­plica­t­ions for fu­ture in­ter­ven­tions aim­ing to help peo­ple change their be­hav­ior, the re­search­ers ar­gued. Most no­ta­bly, they said, the results sug­gest that if peo­ple even tem­po­rarily don’t real­ize they have lost con­trol, they will be un­able to stop or change their be­hav­ior on their own.

* * *

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Drug abuse, crime and obesity are but a few of the problems modern society faces, but they all have one thing in common: people’s failure to control themselves in the face of temptation. While the ability to restrain our impulses is a defining feature of the human animal, its failure is one of society’s central problems. Why do we so often lack this crucial ability? As humans, we have limited resources to control ourselves, researchers say; all acts of control draw from this same source. So when using this resource in one domain, such as dieting, we’re more likely to run out of this resource in another domain, like studying hard. Once these resources run out, our self-control ability is diminished. The dieter is more likely to eat chocolate, the student to watch TV, and the politician to accept a bribe. In a recent study, Michael Inzlicht of the University of Toronto Scarborough and colleague Jennifer N. Gutsell offer an account of what’s happening in the brain when our vices get the better of us. Inzlicht and Gutsell asked participants to suppress their emotions while watching an upsetting movie. The idea was to deplete their resources for self-control. The participants reported their ability to suppress their feelings on a scale from one to nine. Then, they completed a Stroop task, which involves naming the color of printed words (i.e. saying red when reading the word “green” written in red), yet another task that requires self-control. The researchers found that those who suppressed their emotions performed worse on the task, indicating that they had used up their self-control resources while holding back their tears during the film. An EEG, performed during the Stroop task, confirmed these results. Normally, when a person deviates from their goals (in this case, wanting to read the word, not the color of the font), increased brain activity occurs in a part of the brain called the anterior cingulate cortex, which alerts the person that they are off-track. The researchers found weaker activity in this brain region during the Stroop task in those who had suppressed their feelings. In other words, after engaging in one act of self-control this brain system seems to fail during the next act. The findings, which appear in the November issue of the research journal Psychological Science, have implications for future interventions aiming to help people change their behavior, the researchers said. Most notably, they added, it suggests that if people even temporarily don’t realize they have lost control, they will be unable to stop or change their behavior on their own.