Changing minds about minds: Evidence that people are too sceptical about animal sentience

Our relationships with other animals are governed by how we view their capacity for sentience and suffering. However, there is currently little agreement as to whether people's beliefs about animal minds are largely accurate or inaccurate. We used an innovative task to examine how people update their beliefs in response to noisy but informative clues about animal minds. This allowed us to compare participants' posterior beliefs to what a normative participant ought to believe if they conform to Bayes' theorem. Five studies (four pre-registered; n = 2417) found that participants shifted their beliefs too far in response to clues that suggested animals do not have minds (i.e., overshooting what a normative participant ought to believe), but not far enough in response to clues that suggested animals have minds (i.e., falling short of what a normative participant ought to believe). A final study demonstrated that this effect was attenuated when humans were the targets of belief. The findings demonstrate that people underestimate animal minds in a way that can be said to be inaccurate and highlight the role of belief updating in downplaying evidence of animal minds. The findings are discussed in relation to speciesist beliefs about the supremacy of humans over animals.