According to new research by the Carlson School's Land O'Lakes Professor for Excellence in Marketing, Kathleen Vohs, people who bottle up emotions all day may be more at risk for aggressive behaviors .

The Limits of Self-Control
By Rick Moore

We spend a good share of our days exercising self-control, whether it's ignoring the pastry on the kitchen counter, or smiling gamely at that ridiculous request from the boss when a rolling of the eyes is the first impulse. But all that seemingly beneficial self-control may come at a cost.

Putting a lid on emotions and impulses may lead to more aggressive behaviors, according to new research by the U's Kathleen Vohs, who has been studying self-control as a limited resource for more than a decade. And that has implications for almost everyone, especially those who must frequently deal with stress and emotional situations.

A disgusting experiment

In the study, Vohs and three colleagues from the University of Texas studied two groups of subjects--one that had been awake for 24 hours straight and another that was fully rested.

All of the research participants were shown two well-known, "disgusting" snippets from movies--the overeating scene from Monty Python's The Meaning of Life and the toilet bowl scene from Trainspotting. Half of the subjects were allowed to react to the clips naturally. The other half were told to keep a completely neutral expression on their face "and, to the best of their abilities, blunt what they're feeling on the inside," Vohs says.

All of the participants then engaged in a computerized competition, where aggression could be measured in their selection of a noise level that would be blasted at their opponents. The results showed that the people who had earlier controlled their emotions when watching the movie clips were more likely to set higher (more aggressive) levels of noise. Further, it was strictly the depletion of their self-regulatory resources that led to the aggression; the lack of sleep was not a factor, Vohs says

"It's not just the experience of negative emotions," adds Vohs, the Land O'Lakes Professor of Excellence in Marketing at the Carlson School of Management. "They're all seeing emotion-evoking information, and they're all feeling that. [But] one group is trying to squash those feelings, and it's that squashing part that's the key--not the feeling of the negative emotions, per se."

Who's at risk of depleted self-control?

Vohs says people possess self-control in finite quantities, no matter how saintly they appear. "People have a resource that exists within themselves, and they use it when they control their behaviors or their responses," she says. "We can predict that they'll be bad at self-control if they've previously used a lot of self-control earlier in that day."\

It's not hard to envision scenarios where these findings come into play. Many in society are called upon to squelch their emotions repeatedly; think police officers and military personnel; impound lot workers and even judges.

"Judges are hearing horrible tales," Vohs says. "Maybe they feel disgusted or they feel angry, maybe they feel contempt. And then, punitively, what do they do after that? Aggression doesn't have to be physical aggression. It can be verbal aggression and punitive responses in general."

Even teachers might be susceptible. Being the face of reason and exemplary deportment all day long has to take a few bites out of the self-control apple.

"There are lots of ways to be punitive and punishing and slightly aggressive, and I think we've all seen that even in our own childhood histories of teachers--maybe verbal slights or even retaliating against the insistent parents," she says. "But you can imagine, they're (the teachers) controlling their emotions all the time throughout the day, mostly in frustration."

Self-awareness of one's self-control limitations can only help. However, that's probably easier said than done. When was the last time anyone said to himself, "I've been exercising a lot of self-control today, so maybe I'm more at risk for road rage?"

And, "The very people who need to realize this effect is happening are the very people who will never realize that this effect is happening," Vohs notes.

Still, it's food for thought, maybe even an excuse for reaching for that pastry. But probably not enough reason to roll your eyes at the boss.

Kathleen Vohs teaches in the Marketing Essentials and Strategic Pricing programs for Carlson Executive Education.