Does Meat-Free Pledging Work? A Smartphone Experiment

Pledging — that is, committing to act in a certain way — is one means of reducing meat consumption. Pledging has successfully changed human behavior in recycling, seatbelt use, and quitting smoking. Although pledges are increasingly popular tools for getting people to eat less meat, there are few studies of their effectiveness. The studies that do exist often explain behavior change as a result of factors beyond the pledge itself, such as a consumer’s motivation to sign up in the first place.   

In this study, researchers explored how a smartphone pledge program impacted consumers’ meat intake over a period of 28 days. They hypothesized that people who experience the “omnivore conflict” would be more successful with the pledge; that pledgers would eat and crave less meat than those in the control group; and that people who took the pledge would be less committed to meat and meat justifications by the end of the study.   

The authors randomly assigned 325 participants (127 from the U.K.; 142 from Germany; 56 from Australia) to either a pledge group or a control group. They asked those in the pledge group to “do their best” not to eat meat during the study period and tracked their daily eating behavior through a smartphone application. It’s important to note that the study only included consumers who identified as “meat lovers,” “omnivores,” “semi-vegetarians/meat reducers,” and “pescatarians.” Consumers were asked to fill out a survey at the beginning and end of the study, then one month later to see how the pledge impacted their meat consumption and attitudes.

Pledging led to reductions in meat consumption levels in all three countries relative to the control group. Germans who pledged to eat less meat had the greatest reductions in meat consumption compared to  Australia and the U.K. According to the authors, Germany’s leadership in meat reduction and the meat alternatives industry could have played a role in this outcome.

Notably, while the authors believed that conflicted omnivores would be more motivated to reduce their meat intake, the results showed that the “omnivore conflict” couldn’t reliably explain meat reduction among pledgers. This is good news, as it means pledges might be effective for all consumers, regardless of their pre-existing conflicts about eating meat. Likewise, one month out from the study, all participants reduced their beliefs in the 4Ns of meat consumption, even if they were in the control group.  Contrary to the authors’ predictions, however, pledgers experienced more meat cravings than those in the control group, and the pledge did not impact overall meat consumption and attitudes toward meat one month after the study ended.

Unlike previous research on pledge programs, this one used experimental conditions and smartphone data, which improved the accuracy of results and limited the errors associated with traditional self-reported data. However, it also had several limitations, including its disproportionately female and white sample. The authors point out that future researchers should test meat-free pledges with non-white, non-female identifying individuals of varying age groups and cultures. 

Organizations and governments have been calling for a shift toward plant-based eating for human health, animal welfare, and the environment. As this study shows, pledging can be an effective way to promote meat reduction, particularly in countries where plant-based eating is popular. However, the authors argue that pledging mainly serves as a temporary way to reduce meat intake. To make pledges more successful, advocates may consider targeting individuals who already show interest in changing their diet. Furthermore, individuals need additional tools and resources beyond the pledge itself to sustain commitments over the long term.