Interventions to reduce meat consumption by appealing to animal welfare: Meta-analysis and evidence-based recommendations

We are pleased to release encouraging results from a new study of animal-related tactics to reduce animal product consumption. Our study collected and synthesized the results of 100 existing studies, which included about 24,000 people across at least 11 countries. To be included, a study had to examine a tactic which depicts farm animals or their suffering. For example, studies specifically on the impact of health or environmental messaging to reduce meat consumption were not included. The included studies tested many different animal-related tactics. Some examples include documentaries, news articles, ethics education, leaflets and even showing photographs of animals on menus serving meat. Based on the results of our study, here are our recommendations:

Advocates should continue to pursue tactics to reduce animal product consumption that emphasize animals and their suffering on factory farms.

• On average, the tactics studied reduced meat consumption. People exposed to a tactic were 22% more likely to report becoming 'low', rather than 'high', meat consumer, compared with people who weren't exposed. 'High' and 'low' meat consumers were defined based on the middle level of self-reported, intended or actual meat consumption in each study. Most studies lasted only a few days, so we don't know how long these effects last.

• This is not a recommendation of animal-related tactics over other tactics, like those using health or environmental messages to reduce meat consumption. Our study did not examine those tactics and so cannot make a comparison. Instead, we recommend continuing to use animal-related tactics because the evidence we found suggests they reduce animal product consumption.

While we are relatively confident animal-related tactics cause some reduction in animal product consumption, we do not know how much reduction.

• Many of the studies might overestimate or underestimate the impact of the tactics they tested. There are many reasons this might be the case and we will only list a few. For example, some studies relied on what people said they ate rather than what they actually ate, and there are known limits to the accuracy of people's memory of their food consumption. In addition, some studies may have attracted participants who were more receptive to the animal-related messages or were otherwise more open to changing their diets. Further, not all participants completed the studies, so we don't know how the tactics affected them. Finally, in some studies the two groups of people compared—those who were and were not exposed to the tactic—may not have been well matched, making the comparison invalid.

• However, when considering only the 12 highest-quality studies, the chance of reporting becoming a low-meat consumer because of the tactic actually increased to about 30%. Since fewer studies were used in this analysis, this number is much less certain. Nonetheless, this may suggest that the lower quality of the other 88 studies did not result in exaggeration of the overall impact.

• In most cases (83%), the studied tactic caused a decrease in animal product consumption, rather than an increase. About half of studies found the tactic made participants 20% or more likely to report becoming low (rather than high) meat consumers. Very few (4%) studies found substantial risk of increasing meat consumption.

Our study does not clearly suggest any particular animal-related tactic or psychological strategy over another.

• There was no clear trend showing which tactics were most effective. Among the top ten, some used writing, pictures or virtual reality to show the suffering of animals on factory farms. Others added information about the health and environmental impacts of factory farming. Still others gave specific suggestions on how to eat less meat or discussed laws to improve how animals are treated on farms.

• There was no clear trend showing which psychological strategies were most effective, although many different strategies were employed. Tactics often employed descriptions of how eating meat is becoming less normal, the emotions of farm animals, individual victims of factory farming, comparisons between farm animals and pets, and specific suggestions for how to eat less meat.

To better understand tactics to reduce animal product consumption, high-quality studies are needed.

• In particular, studies with large samples, randomization, control groups, long follow-ups and measures of actual behavior change are required. Such studies are more expensive, but at this point we will learn more from doing fewer, more expensive studies than many cheaper ones. Collaborations between advocacy organizations to pool resources may be helpful.

• To understand which particular tactics and psychological strategies are most effective, similarly high-quality studies which directly compare tactics will be needed.

Read more in the full report or press release. Download the data and code or review the pre-registration.