Effectiveness of a theory-informed documentary to reduce consumption of meat and animal products: three randomized controlled experiments

Link to read the full article

Recommendations

  • Evidence does not support the use of informational documentaries.

  • Interventions that change intended eating habits may not result in actual change in eating habits. In our study, even very large changes in intention did not change actual behavior.

  • Future studies should ensure that participants are unaware of the study’s purpose. They can do this with blinding.

Key Findings

  • Tested a 20-minute documentary “Good For Us that highlights the environmental, human health and animal welfare harms of eating meat and other animal products.

    • In a randomized controlled experiment, compared the documentary to a control video (a generic motivational speech). Participants were from the general population of the United States.

    • Followed up 12 days later with a survey that was described as a different study. This helped to “blind” participants to the purpose of the study when collecting data, reducing potential bias.

  • Our first study found the documentary had no effect on a variety of different outcomes.

    • Found no reduction in animal product consumption. The average change we measured in one study was less than a 1-ounce reduction in animal product consumption per week, with a 95% confidence interval ranging from a 6 ounce reduction to a 5 ounce increase.

    • Found no change in moral valuation of animals (“speciesism”).

    • Found no meaningful increases in interest in animal activism or in perceived importance of environmental sustainability, animal welfare, or eating a healthful diet.

  • Our second study was deliberately designed less rigorously, to resemble previous studies that measured intended behavior. Immediately after the documentary, asked viewers if they planned to eat more or less animal products next week. Many viewers planned to eat less animal products in the week after seeing the documentary.

    • Documentary made viewers 242% more likely to intend to reduce meat consumption than participants who viewed the control video. Critically, our first study suggested that these intentions do not actually translate to reductions in consumption.

    • A previous meta-analysis suggested that comparable interventions make people about 22% more likely to intend to reduce their meat consumption. So our documentary was likely very convincing relative to other interventions, but still not effective at reducing consumption in our more rigorously designed study.

  • Our third study tried to make the documentary more effective. Added a pledge, goal-setting exercises, and reminder email; and participants were people interested in nutrition research. The documentary still was not effective by any measurement. Also looked at just people who attended at least a 2-year college and identified as Democrats, but still no effect.