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To Make Change, Start With a Crowd

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Two smiling women holding bags of goods

It's hard to change people's behavior.


Changing the behaviors of an entire group of people can be easier than changing just one person at a time.


During World War II, the United States shipped meat overseas to feed its soldiers and allies, which raised the cost of meat here at home. And so people ate less meat. Fearing protein deficiencies, the U.S. government wanted people to switch to eating kidneys, brains, hearts, stomachs, intestines, and other so-called “organ meats,” which were cheaper and more plentiful. Yet many people perceived these meats to be low-class or rural foods, and so would not add them to their own diets.

Kurt Lewin set out to change that perception. Widely regarded as the father of social psychology, Lewin first determined that women, not their husbands or children, usually controlled which foods appeared on American tables. He then recruited 85 Midwestern midwives to participate in a research study and randomly assigned them one of two conditions.

In the lecture condition, groups of about 15 women heard a nutritionist lecture about how to incorporate organ meats so that they could improve their family’s nutrition and help the war effort. They learned how to work around the telltale odor, texture, and appearance of these meats, and received recipes to try at home.

In the group decision condition, groups of women learned similar facts and cooking techniques from a nutritionist. But instead of passively receiving this information, they actively participated in a discussion about how to change Americans’ eating habits to cope with wartime food shortages. When they offered their own personal objections, such as a personal dislike of organ meats, the nutritionist offered persuasive counterarguments, such as cooking tips for making organ meats taste better At the end of the meeting, the nutritionist asked the women to raise their hands if they were willing to try organ meats in the upcoming week.

One week later, researchers interviewed each housewife. They discovered that 23 out of 44 participants (52%) in the group decision condition had served organ meats, while only 4 out of 41 participants (10%) in the lecture condition had given tripe and other less fancy flesh a try. 

The group decision technique was even more effective among participants who had never served organ meats. 29% of these first-timers in the group decision condition served organ meat, compared to 0% in the lecture condition. 

Why This Works

Food arrives on people’s tables by various routes or channels, such as buying it at the supermarket or growing it in the garden. Lewin called the person who controls the channels that food follows into the household “the gatekeeper.” In the 1940s, the gatekeeper was usually a housewife. Lewin changed food habits by understanding “the psychology of the gatekeeper,” and especially housewives’ thoughts about “what people like me eat.”

Women at the time tended to think of organ meats as “food other people eat.” By having women discuss, decide, and publicly commit to giving organ meats a try, Lewin helped these women see organ meats as “food that people like use at,” which paved the way to women actually buying and serving these cuts to their families. 

When This Works Best

For the group decision technique to work, people have to feel like they came to a decision on their own through free discussion and voluntary commitment. Of course, the group leader pushes participants toward the target behavior change, and peer pressure also exerts a force, but the process of the discussion must appear to be democratic. Group decision also works best when participants feel similar to each other, and thus feel that any change other group members adopt can also apply to themselves. 

The Original Study

Lewin, K. (1943). Forces behind food habits and methods of change. Bulletin of the National Research Council108, 35-65.

Related Topics

Education Health


Photo CC by Boston Public Library

Photo card CC by Kheel Center

Thumbnail image via Timon Studler / Unsplash