In its current usage within the literature, speciesism seems to function as an umbrella term for multiple related phenomena, which has contributed to conceptual fragmentation. This fragmentation raises the risk of a jingle fallacy, in which different underlying constructs are treated as if they were the same because they share the label “speciesism.” Often, slightly different elements of speciesism are measured, ranging from moral concern for animals, attitudes about exploitation, to beliefs about human supremacy. To bring greater structure to this literature, we highlight three key sources of variation in studies on speciesism: the target of evaluation, the frame of reference, and the type of discrimination involved. Making these distinctions explicit provides a clearer framework for organising existing findings and for interpreting what different measures of “speciesism” actually capture.

One way in which studies of speciesism differ is the target of evaluation. Speciesism can be directed toward any species and studies vary considerably in the nonhuman animals they ask participants to consider. Some assess attitudes toward animals in general, whereas others focus on a specific subset of animals or on only one or two animals. Commonly encountered animals—such as companion or farm animals—are studied far more frequently than less familiar species, which have received comparatively little empirical attention. As a consequence, findings derived from evaluations of a limited set of familiar animals may not readily generalise to attitudes toward other species, limiting conclusions about speciesism as a broader pattern of interspecies evaluation.

In addition to differences in target, studies also vary in their frame of reference. The majority of research has focused on anthropocentric speciesism, defined as the preferential evaluation or treatment of humans relative to nonhuman animals, while other studies investigate how nonhuman animals are evaluated relative to one another. A prominent example is research on pet (or companion animal) speciesism, which documents the tendency to attribute greater moral worth to companion animals than to other nonhuman animals. Beyond this contrast, comparisons among other animals are relatively rare, leaving large portions of the moral hierarchy between species underexplored.

A further source of heterogeneity lies in the type of discrimination under investigation. Speciesism can manifest both in the assignment of different levels of moral worth and in support for practices that exploit or disadvantage certain animals. Critically, these different manifestations do not always align with one another: people may express moral concern for animals while still participating in or endorsing practices that harm them. This discrepancy is captured by the concept of the attitude–behaviour gap, and exemplified in the meat paradox (Loughnan et al., 2010): many people care about animals, yet continue to consume meat. This can also work in the other direction: people may believe that humans have a higher moral worth compared to animals and yet disagree with exploitative practices towards animals. Some interventions, for example, can reduce harmful actions while speciesist views remain unchanged (Banach & Stel, 2024). For this reason, measures that focus only on moral worth or only on disadvantageous treatment may be capturing related but distinct dimensions of speciesism.

This variability in targets, frames of reference, and type of discrimination complicates comparisons across studies and raises questions about the generalisability of findings. A more comprehensive account of speciesism therefore requires systematic attention to these diverse manifestations of speciesism, as well as an examination of how they relate to one another. One possibility is that some of these phenomena reflect distinct dimensions of a multidimensional construct, but this remains an open empirical question. Explicitly disentangling these different manifestations would improve conceptual clarity and enhance the interpretability and comparability of findings across studies.

Having highlighted key elements researchers should consider when measuring speciesism—its multiple targets, frames of reference, and types of discrimination—the next question is how future measures might better reflect this complexity. One possible direction for future research would be the development of more comprehensive measures of speciesism that integrate these dimensions within a single framework. Such measures could include a broader range of animal targets and assess both the moral value attributed to different species and support for practices that harm or disadvantage them. By incorporating multiple species within the same instrument, such measures would allow for different frames of comparison, including evaluations of humans relative to nonhuman animals as well as comparisons among nonhuman animals themselves.

Beyond decisions about which animals are included, which comparisons are made, and which manifestations of discrimination are assessed, it is equally important to ensure that measurement approaches minimise confounds that could obscure interpretation. The following considerations highlight how common operationalisations may introduce such confounds, and how future work might address them.

One common measure of speciesism is to employ forced-choice moral dilemmas, where participants choose between saving a human or an animal. Such paradigms offer a clear comparison between species, but they rest on zero-sum assumptions: the participant must choose one over the other, making it impossible to act in a way that is fully non-speciesist. Any choice in such a dilemma automatically favours one species and is thus “speciesist” by default. In real-world situations, people are often able to extend moral concern to both humans and animals simultaneously (with some exceptions, such as ethical dilemmas in machine ethics or extreme emergencies). Moreover, moral dilemmas may also conflate moral worth with instrumental value. For example, a participant may choose to save a pig not due to perceived moral worth but because of its perceived utility as food. We recommend replacing or complementing forced-choice dilemmas with measurement approaches that allow for non-zero-sum responding. For example, measures that permit participants to endorse concern for multiple targets, or to justify their choices, may better capture the complexity of moral reasoning.

Another common strategy is the use of self-report scales that rely on concrete or context-specific items, such as asking people’s views on the acceptability of using animals in entertainment or for science. While these items can be informative about support for particular practices, Caviola et al. (2019) note that such items risk conflating moral values with empirical beliefs. People’s responses may be shaped not by how much moral concern they have for animals, but by factual disagreements about how well animals are treated in these contexts. To address this, researchers could design measures that clearly distinguish between normative evaluations and descriptive beliefs. For example, items could assess moral principles “It is morally wrong to let animals suffer for human gain” instead of concrete practices “It is morally wrong to use animals in laboratories”. Separating these components allows for a more precise assessment of speciesism independent of empirical assumptions, reducing confounds and improving interpretability.

There are several areas where the conceptualisation and measurement of speciesism could benefit from further clarification. We encourage researchers to consider which specific aspect of speciesism they aim to examine—whether the construct in its entirety or a particular manifestation—and communicate clearly which manifestation is being measured. Furthermore, operationalisation that avoids potential confounds will help ensure that measures accurately capture the intended construct. To advance the field, future research could develop a comprehensive measure of speciesism that encompasses multiple targets, frames of reference, and types of discrimination. Ongoing efforts to refine our understanding of speciesism allow researchers to better identify the drivers of practices such as meat consumption, animal experimentation, or neglect of certain species, and in turn inform strategies to reduce these harms.