The moral standing of animals: Towards a psychology of speciesism

Lucius Caviola, Jim A.C. Everett, Nadira S. Faber
Journal of Personality and Social Psychology

We introduce and investigate the philosophical concept of ‘speciesism’ — the assignment of different moral worth based on species membership — as a psychological construct. In five studies, using both general population samples online and student samples, we show that speciesism is a measurable, stable construct with high interpersonal differences, that goes along with a cluster of other forms of prejudice, and is able to predict real-world decision- making and behavior. In Study 1 we present the development and empirical validation of a theoretically driven Speciesism Scale, which captures individual differences in speciesist attitudes. In Study 2, we show high test-retest reliability of the scale over a period of four weeks, suggesting that speciesism is stable over time. In Study 3, we present positive correlations between speciesism and prejudicial attitudes such as racism, sexism, homophobia, along with ideological constructs associated with prejudice such as social dominance orientation, system justification, and right-wing authoritarianism. These results suggest that similar mechanisms might underlie both speciesism and other well-researched forms of prejudice. Finally, in Studies 4 and 5, we demonstrate that speciesism is able to predict prosociality towards animals (both in the context of charitable donations and time investment) and behavioral food choices above and beyond existing related constructs. Importantly, our studies show that people morally value individuals of certain species less than others even when beliefs about intelligence and sentience are accounted for. We conclude by discussing the implications of a psychological study of speciesism for the psychology of human-animal relationships.

Overview of Paper


Speciesism is a concept much discussed in the philosophical literature on our treatment of animals, referring to the assignment of different inherent moral status based solely on an individual’s species membership. Descriptively, speciesism is a concept that explains how people behave; namely that they do, as a matter of fact, assign moral worth to individuals on the basis of species membership, such that people can therefore be accurately described as having speciesist attitudes. Normatively, much work on speciesism is rooted in the claim that people should not assign different moral values to individuals based solely on their species membership, with analogies made with treating people differently solely based upon their race (racism) or gender (sexism).

In this paper, we present speciesism as a psychological construct, suitable for psychological investigation. Specifically , we are interested in the empirical truth of the psychological claims implicit in the philosophical discussion of speciesism: first, the primary claim that people assign moral worth to individuals on the basis of species membership alone; and second, the claim that speciesism is a form of prejudice analogous to other prejudicial attitudes. Philosophers have debated these claims, but relatively little empirical work has been conducted to test whether these claims are, as a matter of fact, true. Do people, in actuality, assign moral worth to individuals on the basic of species membership; and are these speciesist attitudes connected to other prejudicial attitudes? By rigorously examining this, it becomes possible to bring the concept of speciesism into the study of intergroup relations and prejudice more generally, thus providing new insights and directions for research for both topics.

Our first aim, upon which all later aims depended, was to develop a reliable and valid scale to measure speciesism as a psychological construct (Studies 1 and 2). Once this was achieved, we looked at the extent to which speciesism can psychologically be considered a form of a prejudice (Study 3), by testing whether speciesism correlates with other forms of prejudice, and whether speciesism, like other forms of prejudice, is driven by socio-ideological factors such as social dominance orientation that maintain other forms of intergroup conflict. To the extent that speciesism is a form of prejudice it should be correlated with prototypical examples of prejudice and be driven by the same kind of processes that drive other prejudices. Finally, we looked whether speciesism predicts behavior, such as the degree of help directed towards individuals of different species or the likelihood of choosing certain food products over others (Studies 4 and 5).


We conducted five studies, using a mixture of participants recruited online via MTurk, and student samples recruited at a British University. An important contribution of our work is the development and validation a 6-item Speciesism Scale with which to explore speciesist attitudes. Further details on the scale, including links for the scale in a Qualtrics format and an R Script for analysis can be found at the link below.

The Speciesism Scale

Results and Discussion

  1. First, we describe the philosophy of speciesism and introduce it as a psychological phenomenon, suitable for empirical investigation. Speciesism has been purported to be a reliable form of prejudice analogous to racism and sexism, and yet the empirical claims behind this have received little attention so far.
  2. Second, we present the Speciesism Scale: A theoretically driven and empirically validated explicit measure of speciesism with high internal consistency and test-retest reliability. This scale confirms that speciesism is an accurately measurable, stable form of prejudice with high interpersonal differences.
  3. Third, we demonstrate that, as originally proposed by philosophers, speciesism can be considered a form of prejudice. We have found that speciesism is psychologically related to human- human types of prejudice such as racism, sexism, and homophobia. This is consistent with the generalized prejudice theory, which assumes that prejudice towards various targets is significantly correlated and can be explained by an underlying generalized prejudice factor (Akrami, Ekehammer, & Bergh, 2011). Our finding that speciesism is strongly related to SDO confirms the SD-HARM model (Dhont et al., 2014), which assumes that speciesism and human-human types of prejudice are underpinned by the same socio-ideological beliefs, namely a general endorsement of social hierarchy and inequality. The fact that speciesism shares these psychological properties with other phenomena we refer to as prejudice seems to strengthen the case that speciesism can be referred to as prejudice as well. We note that in comparison to human-human forms of prejudice, speciesism is the dominant and explicitly accepted social norm and ideology in current Western societies. Consequently , people who endorse the current status quo and people on the political right tend to score high on speciesism, whereas actively open- minded thinking seems to facilitate questioning that norm. We also identified lower levels of empathic concern as an additional factor associated with speciesism.
  4. Fourth, we demonstrate that speciesism can predict behavior above and beyond existing constructs. In doing so, we believe we are the first to systematically show effects of speciesist attitudes on actual, observable behavior. In two studies we found that speciesism predicts people’s willingness to help humans and “superior” animals such as dogs (rather than “inferior” animals such as pigs), in terms of allocating donation money and investing time. We also found that speciesism predicts people’s (meat vs. vegetarian) food choices. This indicates that speciesism captures an important but neglected aspect of both discrimination and prosociality.