The Moral Standing of Animals: Towards a Psychology of Speciesism - Jim AC Everett
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The Moral Standing of Animals: Towards a
Psychology of Speciesism
Journal of Personality and Social Psychology
Lucius Caviola, Jim A.C. Everett, and Nadira S. Faber
University of Oxford
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.
Keywords: speciesism, prejudice, prosocial behavior, human–animal relations, helping
© 2018, American Psychological Association. This paper is not the copy of record and may not exactly
replicate the final, authoritative version of the article. Please do not copy or cite without authors permission. The
final article will be available, upon publication, via its DOI: 10.1037/pspp0000182
Please note that this the authors' copy of the published manuscript, provided for the purpose of disseminating
academic research openly. For referencing purposes, please see the final published manuscript for the correct
page numbers.THE MORAL STANDING OF ANIMALS Page 2
The Moral Standing of Animals: Descriptively, speciesism is a concept that
explains how people behave; namely that
Towards a Psychology of
they do, as a matter of fact, assign moral
Speciesism worth to individuals on the basis of
species membership, such that people can
Human relationships with non-human therefore be accurately described as
animals are complex. Some animals are having speciesist attitudes. Normatively,
treasured as pets, receive our love and much work on speciesism is rooted in the
devotion and are provided with a diet and claim that people should not assign
quality of health care better even than different moral values to individuals
some humans in the developing world. based solely on their species membership,
Other animals, in contrast, are factory with analogies made with treating people
farmed and slaughtered so that their differently solely based upon their race
bodies can provide the meat we share (racism) or gender (sexism). This paper is
with our pets. Yet other animals are concerned with speciesism as a
regarded as experimental subjects, sources psychological phenomenon and,
of entertainment, or industrial equipment. therefore, in a descriptive sense.
Any observer who had not been socialized Speciesism manifests itself in the near-
to view this as normal would likely be universal belief that humans are
struck by this inconsistency of moral intrinsically more valuable than
worth attributed to animals in human individuals of other species. It also
societies. In this paper, we attempt to manifests itself in the belief that
understand this paradoxical treatment by differential treatment of species that have
importing the philosophical concept of comparable mental and emotional
speciesism into a social-psychological capabilities, such as pigs and dogs, is
examination of human-animal morally justifiable. These manifestations
relationships. of speciesism are ubiquitous,
underpinning practices such as the mass
The Philosophy of Speciesism factory farming of animals for food, the
use of animals for human entertainment
Philosophers have long noted the in circuses, and legal systems that view
inconsistency in our regard for animals, animals as property and deny them basic
but it is only in recent decades that the rights such as the right to bodily integrity.
systematic consideration of human-animal For example, we treat dogs with special
relations has really flourished and entered moral status while simultaneously factory
the public domain. Our relationships with farming and eating pigs — despite the fact
animals have been called “speciesist” — a that dogs and pigs have similar mental
term introduced and popularized in the and emotional capabilities (Mendl, Held,
1970s and specifically intended to draw a & Byrne, 2010). Such manifestations of
parallel with other forms of unjustified speciesism are, descriptively, familiar to
discrimination, such as racism and sexism all, even if one might deny there is
(Horta, 2010; Ryder, 2006, Singer, 1975; anything, normatively, wrong with this.
1979; Singer & Mason, 2007). Speciesism, Speciesism—like racism and sexism—is
in the philosophical literature, refers to the observed throughout history and across
assignment of different inherent moral cultures. Just like ethnic prejudice is
status based solely on an individual's observed in all societies but is directed
species membership. As implicit in the against different groups based on local
definition of speciesism and its very traditions and history, speciesism appears
name, speciesism can be understood in evident across cultures but is expressed
both a descriptive and a normative sense. differently across the world (see Amiot &
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 3
Bastian, 2015). Consider dogs and cats: in And yet, careful analysis suggests that this
China they are considered food and thus is not the case. When each of the above
akin to other animals like pigs, but in reasons is investigated more fully, they
Western societies they are seen as ‘one of are shown to be incomplete explanations
the family’ and thus have a much higher (see, for example, Horta, 2010).
status than pigs (Simoons, 1990). Or a) First, the argument from cognitive
consider cows: routine fare on the dinner abilities (i.e. that humans devalue
plate in many Western countries, but animals because they are less
forbidden from being eaten and revered cognitively able than humans) fails
as sacred animals in Hindu societies. to account for why people place
These culturally determined different moral value on different
manifestations of speciesism occur not just animals that have similar cognitive
across cultures but also across time. abilities. Pigs, for example, have
Horses were once routinely consumed in higher cognitive abilities than
Western countries for centuries, but now dogs, and even pass a weak
horsemeat consumption has substantially version of the mirror test,
declined and the perceived moral status of indicating some level of self-
horses has increased (Gade, 1976). awareness (Broom, Sena &
At this point, one might ask whether it Moynihan, 2009). It cannot,
is really speciesism that best explains why therefore, simply be cognitive
we treat people and animals differently abilities that determine treatment,
based on their species (for philosophical because otherwise pigs would be
criticism of speciesism as a concept see treated as equal, and maybe even
Diamond, 1978; Kagan, 2016, Williams, superior, to dogs. Of course, some
2009). Just as it has been argued in history people might morally value pigs
that unequal treatment of races is morally less than dogs because they
justified because members of different incorrectly assume that pigs are
races (supposedly) differ in their less intelligent than they actually
intelligence or physical capabilities, might are, which might be driven by
it not be species membership per se that motivated reasoning (e.g. Bastian
results in differential treatment, but rather et al., 2012). But such incorrect
other traits that happen to correlate with assumptions and/or motivated
species membership? Three of the most reasoning cannot explain clear
common objections to the utility of the cases of people valuing certain
speciesism concept, raised by individuals less despite being fully
philosophers and laypeople alike, are that aware that they are equally or
rather than reflecting a speciesist bias, more intelligent than others (for
humans devalue animals because: a) example, chimpanzees vs. severely
animals are less cognitively able than mentally disabled humans, see
humans; b) animals, unlike humans, point b).
cannot be moral agents (i.e. they cannot b) Second, the arguments from both
reciprocate in moral interactions and cognitive abilities and moral
cannot be held morally or legally agency (i.e. humans devalue
responsible for their actions); or c) animals animals because animals, unlike
are less sentient (i.e. able to feel and humans, cannot be moral agents)
experience things such as suffering) than are countered with the example of
humans. severely mentally disabled
Were any of the above the true cause humans. Humans grant equal
of human treatment of animals, moral status to severely mentally
speciesism would be a redundant concept. disabled humans and healthy
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 4
individuals despite their lack of species membership. And even if one
cognitive and reciprocal abilities— disagrees on just how unconvincing these
they may even grant such criticisms are, it seems clear that they are
individuals enhanced moral status not strong enough to halt discussion of
in light of their vulnerability. speciesism in its tracks. From a
Moreover, it seems that most philosophical perspective, the paradoxical
people would place less moral treatment of animals can be usefully, and
value on a chimpanzee than on a informatively, described as speciesist.
human with very severe mental And indeed this is where speciesism has
disabilities even in cases where most often been used—in philosophy. But
they know that the chimpanzee could speciesism also be a useful
has higher cognitive abilities than psychological construct, shedding deeper
said human. Neither cognitive light on the way that humans think about
abilities nor the potential for animals? We argue that it can.
reciprocal morality, then, seem to
accurately account for the way we
The Psychology of Speciesism
treat members of different species,
because otherwise we should In this paper, we present speciesism as
afford greater weight to the a psychological construct, suitable for
treatment of intelligent animals psychological investigation. Specifically,
over severely disabled humans. we are interested in the empirical truth of
c) Third, the argument from the psychological claims implicit in the
sentience (i.e. animals do not feel philosophical discussion of speciesism:
and experience things such as first, the primary claim that people assign
suffering) fails because empirical moral worth to individuals on the basis of
data has shown that many animals species membership alone; and second,
— and in particular vertebrate, like the claim that speciesism is a form of
pigs, dogs, and cows — are prejudice analogous to other prejudicial
capable of suffering to an extent attitudes. Philosophers have debated
analogous to humans (Low et al., these claims, but relatively little empirical
2012). It is possible, however, that work has been conducted to test whether
people systematically these claims are, as a matter of fact, true.
underappreciate the level of Do people, in actuality, assign moral
sentience in many animals. worth to individuals on the basic of
Moreover, even in the absence of species membership; and are these
this overwhelming scientific data, speciesist attitudes connected to other
we can observe that people do not prejudicial attitudes? By rigorously
typically doubt the sentience of, examining this, it becomes possible to
for example, human infants — bring the concept of speciesism into the
despite the fact that the behavior study of intergroup relations and
of infants offers weaker evidence prejudice more generally, thus providing
for sentience than the behavior of, new insights and directions for research
for example, an average adult for both topics.
chimpanzee. Our preliminary aim, upon which all
later aims depend, was (Aim I) to develop
Given these arguments, the standard a reliable and valid scale to measure
objections to the utility of the speciesism as a psychological construct
philosophical concept of speciesism are (Studies 1 and 2). Once this was achieved,
unconvincing. People do seem to assign we aimed to look at (Aim II) the extent to
worth to different species solely on which speciesism can psychologically be
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 5
considered a form of a prejudice (Study 3), Previous Research
by testing whether (Aim IIa) speciesism
As noted above, surprisingly little
correlates with other forms of prejudice,
psychological research has focused on the
and whether (Aim IIb) speciesism, like
discrimination against animals (for one of
other forms of prejudice, is driven by
the first papers, see Plous, 1993). There
socio-ideological factors such as social
are, however, some previous and more
dominance orientation that maintain other
recent studies on human-animal relations,
forms of intergroup conflict. To the extent
their underlying attitudes, mechanisms
that speciesism is a form of prejudice it
and resulting practices that suggest it is in
should be correlated with prototypical
fact useful to consider speciesism in terms
examples of prejudice and be driven by
of intergroup bias, prejudice, and
the same kind of processes that drive
discrimination.
other prejudices. Moreover, we aimed to
explore the relationship between The Social Dominance Human-Animal
speciesism with empathic concern and Relations Model (SD-HARM)
actively open-minded thinking (Aim IIc). The first connection between
Finally, we aimed to look at (Aim III) speciesism and intergroup bias comes in
whether speciesism predicts behavior, the form of social dominance orientation
such as the degree of help directed (SDO: Pratto, Sidanius, Stallworth, &
towards individuals of different species or Malle, 1994). People differ in how much
the likelihood of choosing certain food they support or oppose group-based
products over others (Studies 4 and 5). dominance and inequality amongst social
To what extent is it reasonable, on groups, and this variance can be referred
empirical grounds, to view speciesism as a to as differences in social dominance
form of prejudice? It is here that orientation. Differences in SDO predict
psychology has a real and important role prejudicial attitudes towards a variety of
to play. If it can be shown that speciesism human social groups, including ethnic
is psychologically related to other forms minorities, housewives, people with
of prejudice, the philosophical case for it mental health difficulties, and people who
can be strengthened. One typical are obese or perceived as unattractive (e.g.
definition of prejudice is that it refers to Duckitt & Sibley, 2007). Critically for a
“any attitude, emotion, or behavior discussion of speciesism, SDO also relates
toward members of a group, which to how people feel about inequality
directly or indirectly implies some between humans and animals. Recent
negativity or antipathy toward that studies suggest that people who believe in
group” (Brown, 2010, p. 7). Speciesism the superiority of humans over animals
seems to fit that definition as it involves also believe in the superiority of some
negative beliefs, emotions, and behavior humans over others (Costello & Hodson,
directed towards others based on species 2009; Dhont & Hodson, 2014; Dhont,
membership. Most people believe that Hodson, Costello & MacInnis, 2014).
pigs matter less than dogs (attitude), feel Accordingly, Dhohnt, Hodson and Leite
disgust towards rats but love towards cats (2016) have proposed the Social
(emotion), and accordingly treat pigs and Dominance Human-Animal Relations
rats much worse than they treat dogs and Model (SD-HARM) whereby the same
cats (behavior). Moreover, in addition to socio-ideological beliefs that legitimize
fitting the definition of prejudice, we aim hierarchies amongst human groups also
to show that speciesism shares properties seem to legitimize hierarchies of humans
and underlying psychological over animals. Such findings suggest that it
mechanisms with other phenomena would be fruitful to consider speciesism in
referred to as prejudice. terms of intergroup conflict, if both
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 6
speciesism and other forms of prejudice people who endorse social dominance are
depend on similar psychological beliefs. able to remove their victims from the
Dehumanization and the Interspecies ‘human’ sphere of moral concern and
Model of Prejudice (ISMP) place them in the ‘animal’ sphere where
no moral consideration is necessary. The
The second connection between
existence of the human-animal gulf
speciesism and intergroup conflict comes
therefore functions to facilitate prejudice
from work on dehumanization, and
and discrimination between groups of
specifically research suggesting that
humans as well as between humans and
intergroup dehumanization is linked with
animals. In support of this theory, it was
beliefs in the superiority of humans over
demonstrated that when similarities
animals. Dehumanization is the
between animals and humans are pointed
psychological process by which other
out not only speciesism is reduced but
people are seen as less “human” and
also moral concern for marginalized
therefore not worthy of full moral
human out-groups is increased (Bastian,
concern, and is a critical part of intergroup
Loughnan, Costello, & Hodson, 2012).
conflict (Haslam, 2006). The language of
dehumanization, such as referring to The Meat Paradox and Carnism
black people as “apes”, Jews as “rats” and A related emerging field of research
women as “bitches”, works to strip the has started to investigate the psychology
victim of moral worth, as it is assumed surrounding practices of eating animals
that actual apes, rats, and dogs could not (Loughnan & Bastian, 2014). Most people
merit full moral consideration. Two do not want to hurt animals, yet continue
distinct accounts have been proposed to to eat meat. This widespread phenomenon
explain the relationship between has been referred to as the ‘meat paradox’
dehumanization and attitudes towards (Loughnan et al., 2010; Loughnan, Bastian,
animals. & Haslam, 2014). Both active (motivated
One the one hand, it has been reasoning) and passive (e.g. social norms)
suggested that just as some people dissonance avoidance can account for the
dehumanize human out-groups by meat paradox (Bastian & Loughan, 2017).
reducing attribution of mental states, they A main driver of the meat paradox is
also de-mentalize animal out-groups. de-mentalization (discussed above).
Specifically, the denial of animals’ People tend to de-mentalize animals they
capability to suffer, known as de- classify as food (e.g. Bastian et al., 2012)
mentalization, can reduce moral concern and judge animals that are categorized as
for animals (Bastian et al., 2012; Kozak, food (e.g. pigs, cows, chickens) as having
Marsh, & Wegner, 2006). Indeed, research lower capability to suffer than animals
shows that a person’s moral concern for that are typically not categorized as food
animals is closely related to how much (e.g. cats, dogs, horses; Bilewicz,
they believe animals can suffer (Waytz, Michalak, & Kamińska, 2016; Bratanova,
Gray, Epley, & Wegner, 2010). Loughnan, & Bastian, 2011). Moreover,
On the other hand, according to the people are more likely to de-mentalize
Interspecies Model of Prejudice (ISMP: animals if they have recently eaten meat
Costello & Hodson, 2014), belief in an (Loughnan, Haslam, & Bastian, 2010) or if
insurmountable human–animal divide is they anticipate eating meat soon (Bastian
the foundation for out-group et al., 2012; Bastian & Loughnan, 2016).
dehumanization. That is, dehumanization It has been argued that meat
is made possible by the moral gulf consumption is legitimized by a set of
between human and animals: By likening ideological beliefs referred to as ‘carnism’
out-group members to ‘inferior’ animals, (Joy, 2011; Monteiro, Pfeiler, Patterson &
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 7
Milburn, 2017). Eating meat, for example, unavailable in the existing literature, for
is justified on the basis of it being natural, multiple reasons.
normal, necessary, and nice (“The 4 Ns”; First, existing scales do not explicitly
Piazza et al., 2015). Furthermore, carnism capture speciesism, as it is properly
shows in the justification of killing defined: Attributing moral status to an
animals for food purposes (Monteiro et individual solely on the basis of their
al., 2017). Conceptually, carnism is a species. Instead, existing scales capture
specific subset of speciesist beliefs and related, yet distinct, concepts such as
practices, namely those related to the general attitudes towards animals or
categorization of certain animals as food. views on animal rights.
Psychologically, we would expect carnism Second, some items in existing scales
and speciesism to be to some extent confound empirical and normative issues.
distinct due to the fact that many people Consider the following item by Wuensch
care about animals in general while at the et al. (2002): “Most cosmetics research
same time defending meat consumption done on animals is unnecessary and
and its practices (i.e. meat paradox). invalid”. This item is limited as it
Overall, however, it seems likely that the confounds the normative belief that
two are not just conceptually but also animals should not be subjected to
psychologically strongly linked. suffering with the empirical belief in the
efficacy of scientific testing. There is no
Measuring Speciesism
way to accurately respond to the item if,
To study speciesism, we need a for example, you believe the research is
convenient way of measuring speciesist scientifically valid but morally abhorrent,
attitudes. There are currently two or if you believe the research is morally
established scales that attempt to capture acceptable but scientifically useless. Or
general attitudes towards animals: consider another item on the scale, which
Herzog, Betchart, and Pittman’s (1991) reads: “There are plenty of viable
Animal Attitude Scale and Wuensch, alternatives to the use of animals in
Jenkins, and Poteat’s (2002) Animal Rights biomedical and behavioral research”
Scale. Both scales capture important (Wuensch et al., 2002). Again, this item is
aspects of people’s attitudes towards flawed as it relates to an empirical fact,
animals. For many reasons, however, we not a belief about the moral standing of
argue that a new scale is needed in order animals. A coherent anti-speciesist could
to examine the psychology of speciesism believe that there are few viable
specifically with sufficient precision. alternatives to the use of animals in
Dhont et al. (2014; 2016) and Piazza et al. research while maintaining testing on
(2015) have also recognized the need for a animals is morally wrong.
new way to measure speciesism, and to Third, a common difficulty in
this end developed ad hoc measurement capturing speciesism is that people who
instruments to help elucidate how endorse anti-speciesism can come to
humans think about animals. However, different conclusions about certain
while these instruments have been used to practices depending on the philosophical
good effect to advance our understanding position they hold, such as
of human-animal relationships, they consequentialism and deontology.
suffer from theoretical limitations and Consequentialism, including
were produced without statistical utilitarianism, is the moral view that the
validation and established scale rightness of an action depends only on its
development procedures. A consequences (Bentham, 1789/1961; Mill,
comprehensive validated measuring tool 1861). Deontology is the moral view that
for speciesism therefore remains certain actions are forbidden irrespective
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 8
of the consequences (Kant, 1785/1964). A To capture all relevant manifestations
consequentialist anti-speciesist might, for of speciesism the item pool should consist
example, agree to harm animals (or of both abstract-general and concrete-
humans) if this were to result in better empirical items. There are benefits and
overall outcome for all sentient beings drawbacks to including concrete items.
(Kahane et al., 2015). A deontological anti- On the one hand, benefits of concrete
speciesist, however, would refuse to harm items include the fact that people’s
animals (or humans) even if the outcome attitudes are likely to be inconsistent and
would be better for everyone. Given this limited by self-serving biases, and
divergence, unless carefully devised, concrete items can expose this
items that, for example, assess people’s inconsistency. For example, people might
attitudes on using animals for medical agree with an abstract item such as
testing can be unhelpful (e.g. some items “species membership is not a morally
by Herzog et al., 1991). This is because relevant criterion”, but disagree with a
they might distinguish between a concrete item such as “animals should not
consequentialist anti-speciesist (who may be hunted for sport”. Another advantage
endorse research using animals if it results of concrete items is that they may be
in the development of a drug that saves easier for laypeople to understand and
many lives in the long run), and a respond to. As this scale is primarily for
deontological anti-speciesist (who may use by laypeople and not philosophers,
reject research using animals because it ease of comprehension is an important
violates a general rule of not harming factor. On the other hand, disadvantages
others). Such a distinction, however, is a of concrete items include the fact that they
factor that should not be captured by a inevitably create empirical confounders.
speciesism scale as, ultimately, the scale Take a person’s views on animals
must be able to identify speciesism performing in the circus, for example. To
without being confounded by unrelated some extent, the issue poses the empirical
specifics of the underlying moral position question of how far circus animals suffer.
a person may hold. People might have different experiences
of circuses, which might cause them to
Requirements for a Speciesism Scale
have different views on the level of
In order to ensure that our scale suffering circuses cause for animals. These
captures the precise philosophical beliefs about circus conditions might be
meaning of speciesism, we outlined the entirely independent of their moral
following requirements to be met: values. Given these arguments about
First, the initial set of items (subjected concrete items, we aimed to strike an
to exploratory factor analysis) should appropriate balance between
capture speciesism both exclusively and philosophically rigorous items and
exhaustively. We assume that speciesism concrete items in the final scale.
will manifest itself both in general beliefs Second, items should avoid
about the moral inferiority of certain normative confounders. In particular, it is
species and in the endorsement of important that items do not prompt
concrete practices involving the use of different responses from deontological
animals. All major manifestations of and consequentialist anti-speciesists. As
speciesism must be covered and core we have explored above, there is the
manifestations of speciesism must receive potential for consequentialist and
appropriate representation, such as the deontological anti-speciesists to be
use of animals for entertainment, food, divided on a number of issues related to
and medical experiments. the treatment or rights of animals.
Therefore, when we referred to an
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 9
empirical situation in our items, we For all studies in this paper, our
ensured the situation was such that most institution’s ethical guidelines were
consequentialist and deontological (anti-) followed and the research was approved
speciesists would reach the same through University of Oxford’s Central
conclusion. University Research Ethics Committee,
with the reference number MSD-IDREC-
Study 1. Scale Development
C1-2014-133.
In Study 1 we began our process of Participants and Procedure
developing the Speciesism Scale (Aim I)
by formulating and testing a pool of 1,122 US American participants took
theoretically-validated items to measure part in the study online via Amazon
speciesism. Mechanical Turk (MTurk), and received a
payment of $0.50 for their participation..
Method Five participants were excluded for not
Item Selection completing the study, and nine because
they failed a simple attention check
To formulate a list of items, we used a embedded in the survey where people
combination of partially modified were asked to select a certain scale point
versions of items from existing scales to confirm they were paying attention.
(Herzog et al. 1991; Wuensch et al. 2002) This left a final sample of 1,108
and entirely new items. We then sent participants (457 female; M = 33, SD =
age
these proposed items to renowned experts 11.56), representing an excellent sample
from a number of disciplines, including size. In contrast to experimental studies
the philosophers Peter Singer and Oscar there are no straightforward and
Horta, and the legal scholar Steven Wise . 1
commonly accepted techniques to
After incorporating feedback from these determine sample size for factor analyses
experts and excluding items that did not (Mundfrom, Shaw, & Ke, 2005). One
meet our criteria, we were left with a 27- approach is to rely on the absolute sample
item pool (see Table 1). In line with our size. Estimations by Comrey and Lee
prerequisites for the scale, these items (1992) suggest that a sample size of 300 is
included both concrete (e.g. “It is morally adequate, and that 1,000 or more is
acceptable for cattle and pigs to be raised excellent. In general, the literature agrees
for human consumption”) and abstract that in exploratory factor analyses the
items (e.g. “Some beings are morally more higher the sample size the better (e.g.
important than others just because they Costello & Osborne, 2005). A different
belong to a certain species.”); and items approach is to aim for a subject-to-item
tapping both the belief in the superiority ratio of at least 5:1 (Gorsuch, 1983), better
of humans over animals (“Morally, 10:1 or higher (Everitt, 1975; Nunnally,
animals always count for less than 1978). Our final sample of 1,108 therefore
humans”) and the superiority of certain represents a size that is more than
animals over other animals (“Pigs should adequate, and with 27 items, gave us an
be taken care of by humans just like dogs excellent final subject-to-item ratio of 41:1.
are”: reverse-scored). Items were presented in randomized
Ethics Statement order and participants were asked to
indicate to which extent they agreed with
the statements on a Likert scale from 1
(strongly disagree), over 4 (neither agree nor
disagree) to 7 (strongly agree). If not further
1
Of course, while we sought feedback specified this response scale was used for
from these experts, we are fully responsible
for these items should any criticism occur.
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 10
all established measures throughout our and the fifth factor 3.83% of the variance
five studies. (eigenvalue = 1.04).
We chose to conduct the study online The scree plot displayed a clear
for a number of reasons. Research inflexion point, which justified retaining
suggests that data obtained via online two factors. As such, we ran a further
platforms such as Amazon analysis, specified to extract two factors.
MechanicalTurk is of high quality The first extracted factor seemed to
(Paolacci & Chandler, 2014) and that capture our intended construct of
results are comparable to results from speciesism including both abstract items
campus studies (Bartneck, Duenser, and more concrete items capturing
Moltchanova, & Zawieska, 2015). attitudes towards animal exploitation and
Importantly for our purposes, it was animal rights. The second factor captured
critical to have a broad sample that is ethical vegetarianism (e.g. “It is morally
representative of the general public in wrong to eat fish”).
terms of education background, gender, Based on theoretical and statistical (see
and age, as speciesism is likely to correlate CFA below) considerations, we decided to
with such factors. Online participants retain the first factor only. It best captured
have been shown to be more diverse the “pure” theoretical construct of
(Shapiro, Chandler, & Mueller, 2013) and speciesism, in isolation from other
highly representative (Buhrmeister, constructs. In this context, it is notable
Kwang, & Gosling, 2011), more so than that factor analysis extracted speciesism
traditional samples (e.g. Berinsky, Huber, and ethical vegetarianism as separate
& Lenz, 2012; Rand, 2012)—largely constructs. This is evidence that the two
because online studies allow for the constructs are psychologically distinct.
recruitment of broader population The speciesism factor and the ethical
samples than the often-limited university vegetarianism factor correlated negatively
student samples. with each other, r = -.35, p < .001.
Items for the further development of
Results
the scale were selected or excluded on the
Exploratory Factor Analysis basis of theoretical and statistical
We first conducted Exploratory Factor considerations. In particular, we focused
Analysis (EFA) using the principal axis on including items with high factor
factors extraction method to determine the loadings while ensuring that theoretically
factor structure of the 27 items. Oblique relevant aspects of speciesism were
direct oblimin rotation was chosen as we captured by the set of items. We
expected that underlying factors would prioritized items that did not include
correlate. The Kaiser-Meyer-Olkin (KMO) empirical assumptions about the
measure of sampling adequacy was .94, intelligence or suffering of animals to
which is above the recommended value of avoid confounding assumptions (e.g.
.6, indicating that individual items shared items three or eight). Our set of selected
enough common variance for such an items contained ten items (Table 1).
analysis. Bartlett’s test of sphericity was
significant: χ (351) = 12,748.82, p < .001.
2 [Table 1]
The first factor explained 34.04% of the
variance (eigenvalue = 9.20), the second Confirmatory Factor Analysis
factor 9.39% of the variance (eigenvalue = In order to examine the model fit of
2.54), the third factor 5.30% of the variance the ten extracted items we performed a
(eigenvalue = 1.43), the fourth factor Confirmatory Factor Analysis (CFA)
5.08% of the variance (eigenvalue = 1.37), relying on maximum likelihood
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 11
estimation in R using the lavaan package entertainment and as such tapped into a
(version 0.5). distinct sub-form of speciesism. Similar
We used a combination of fit indices to redundancies were found between items
judge the model fit. Our primary model fit five and seven that were both highly
index was the Comparative Fit Index abstract without tapping into real-world
(CFI) score, which indicates how well the examples, items six and nine both tapped
data fits the target model compared to an into the domain of research use with
independent model that assumes animals, and items twelve and seventeen
uncorrelated variables. CFI is frequently both captured attitudes towards animal
reported and, in comparison to other fit rights. Given these redundancies, we
indices, not unduly influenced by sample chose to exclude items four, six, seven,
size (Fan, Thompson, & Wang, 1999). and twelve from the final scale, as they
Based on recommendations in the did not serve any additional explanatory
literature we considered a model to have purpose.
an acceptable fit if its CFI score was .93 or A second CFA with the remaining six
higher (Byrne, 1994). Due to the items was then conducted. The CFI was
robustness of the CFI we decided to reject .98, which suggests adequate model fit.
any model that would not meet the TLI was .96, which indicates excellent fit.
required CFI standard. SRMR was .07, which is in the range of
For models with an acceptable fit acceptable values. In contrast, to the
according to CFI we furthermore already mentioned fit indices, the Chi-
considered the Tucker-Lewis Index (TLI), square test yielded a poor fit, χ (9) = 52.87,
2
which is an incremental fit index and p < .001. However, as mentioned the Chi-
must lie above .90, and ideally above .95 square test is considered to be an
(Hu & Bentler, 1999; Marsh, Balla, & unreliable fit index for which reason we
McDonald, 1988). We also applied the did not strongly weight its result but still
more traditional Chi-square test. report it for completeness sake. As such,
However, it must be noted that the Chi- CFA indicated that the model of the six-
square test for CFA is considered to be an item scale was an appropriate fit.
unreliable fit index since it is very Furthermore, a Kolmogorov-Smirnov test
sensitive to sample size and will usually for normality suggested that the scores
result in significant outcomes for sample were normally distributed, D(1108) = .02,
sizes larger than 200 (Steiger, 2007). p = .20.
Finally, we considered the Standardized Finally, we conducted a third CFA in
Root Mean Square Residual (SRMR), which we tested the model fit of a two-
which represents the standardized factor model, which includes both the
discrepancy between the predicted and speciesism and ethical vegetarianism
observed correlation and must lie below factor. The model included the six
.08 to justify adequate model fit (Hu & speciesism items and five ethical
Bentler, 1999). vegetarianism items that loaded onto the
A first CFA revealed an unsatisfactory second extracted factor (Table 1). The
model fit with a CFI of 0.88, which lies model fit, however, was unsatisfactory
below the required standard (TLI = .85; (CFI = .88; TLI = .85; SRMR = .08). Only
SRMR = .06). Results showed that after removing items 26 and 27 the model
unexplained variances correlated highly fit became satisfactory (CFI = .96; TLI =
among each other. This implied that .94; SRMR = .05). However, due to its low
certain items shared variance among each item count and its non-normally
other that was not captured by general distributed scores (Kolmogorov-Smirnov
speciesism. For example, items two and test for normality: D(1108) = .11, p < .001)
four both captured the use of animals for we do not recommend using the ethical
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 12
vegetarianism factor as a measurement and empirically sound Speciesism Scale. A
instrument. combination of EFA, CFA, and reliability
Confirmatory Factor Analysis on a analysis supported the development of a
Separate Dataset one-dimensional scale. All six items
strongly loaded onto a single speciesism
In order to confirm our six-item one-
factor, which had good model fit and high
factor solution we collected a new set of
internal consistency, and this model was
data with which to test our model. 200 US
confirmed by an additional CFA
American participants took part in the
conducted on a separate dataset. Most
study online via MTurk and received
importantly, the scale fulfills all
$0.70 for taking part. Four participants did
requirements that were stipulated at the
not complete and nine were excluded for
beginning of the study: all items explicitly
failing the attention check question. This
capture speciesism and the scale
left a final sample of 187 US American
encompasses crucial aspects of the
participants (89 female; M = 35.73, SD =
age
theoretical concept; experts in relevant
10.36). This sample size is again adequate
fields validated all items; the scale consists
according to the rule of thumb of aiming
of both abstract and empirical items; and
for a subject-to-item ratio of at least 1:10
does not contain items eliciting empirical
(Everitt, 1975; Nunnally, 1978) as in our
and normative confounding factors.
case the ratio was 31:1. Furthermore, our
It is interesting that speciesism and
sample size nearly equals Jackson’s (2001)
ethical vegetarianism were — despite
recommendation to recruit a minimum of
being strongly correlated —
200 participants for CFA relying on
psychologically distinct factors. At first
maximum likelihood estimation.
blush, this result might be surprising, as
Participants responded to the speciesism
one might expect that endorsement of
items and demographic questions. This
anti-speciesism would consistently result
new data set provided very strong
in endorsement of ethical vegetarianism.
evidence for the six-item model, where the
However, this finding is consistent with
CFI was .99, TLI was .99, the SRMR was
previous research on the meat paradox
.02, and even the Chi-square test yielded
(Bratanova, et al, 2011; Bastian &
an acceptable fit, χ2(9) = 11.87, p = .22.
Loughnan, 2016). People might endorse
The Speciesism Scale anti-speciesism in the abstract or in
Based on a series of EFA and CFAs, domains where it does not conflict with
we arrived at our final items to form a their personal preferences, but they
Speciesism Scale (Table 2). The Speciesism employ specific beliefs and practices in
Scale consists of six items all loading onto the context of food (i.e. carnism; Monteiro
a single factor. Speciesism scores were et al., 2017; Piazza et al., 2015).
normally distributed across the sample
with a mean of 3.64 (SD = 1.25) where the Study 2. Temporal Stability
minimum was 1 and the maximum 7.
Reliability analyses yielded that the six- We have hypothesized that speciesism
items scale had high internal consistency, is a psychological form of prejudice
with a Cronbach’s alpha of .81. analogous to other psychological forms of
prejudice such as racism or sexism. If this
[Table 2] is the case speciesism should — like other
forms of prejudice — be a relatively stable
construct that persists over time. Of
Discussion course, like any other form of prejudice,
The goal of Study 1 was the the extent to which a person holds
development of a theoretically informed speciesist attitudes can fluctuate
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 13
depending on the situation and other M = 36.82, SD = 11.51) completed the
age
conditional factors. Ultimately, however, retest study (giving a higher-than-
the extent to which a person holds expected response rate of 49%), and all
speciesist attitudes should stay relatively participants again received $0.50 payment
stable over time because otherwise for taking part. No participants were
speciesism could not be considered a excluded at this stage, and this final
psychological prejudice analogous to sample of 333 is more than adequate,
racism or sexism, but a short-term belief exceeding minimum recommendations for
connected to spontaneous emotional test-retest analyses (Shoukri et al., 2004).
reactions. In order to investigate the
Results and Discussion
temporal stability of speciesist attitudes,
we examined the test-retest reliability of Internal consistency was high for both
the Speciesism Scale over a period of four stages of the study with a Cronbach alpha
weeks. To the extent that speciesism does of .89 for the first stage and .90 for the
represent a stable prejudice, scores at the second stage of the study, and—
two times should be highly correlated. critically—a retest analysis with the 333
cases revealed a test-retest correlation
Methods coefficient of r = .88, p < .001. That is,
The study consisted of two stages: a participants’ scores on the Speciesism
first stage in which participants completed Scale were very highly correlated with
the speciesism scale, and then a second their scores on the same scale four weeks
stage four weeks later in which these same later. The high test-retest reliability is an
participants were invited to again important part of establishing speciesism
complete the scale. In the first stage, 685 as a temporally stable psychological
participants took part via MTurk and prejudice and demonstrates that
received a payment of $0.50 for their speciesism—similar to racism or sexism—
participation. Eight participants were is not just a short-term belief or emotional
excluded for failing the attention check reaction, but a stable view that persists
question, leaving a final sample of 677 US over time.
American participants (305 female; M = age Although our primary purpose for this
34.37, SD = 10.94). We conservatively study was to consider test-retest
assumed a response rate of around 30% reliability, given that for the first sample
for the second stage of the study and an we had a sample size of 677, we decided
expected effect size (Pearson correlation to subject the resulting speciesism ratings
coefficient) between 0.6 and 0.8. Based on to an additional CFA to investigate if our
sample size calculations for test-retest six-item one-factor structure revealed in
analyses in the literature (Shoukri et al., the two independent samples of Study 1
2004) we decided to aim for at least 200 holds a third confirmatory test. Results
responding participants in the second confirmed once again that our six-item
stage and as such aimed to recruit 680 in model had excellent fit (CFI = 0.98, TLI =
the first stage (given the expected 30% 0.97, SRMR = 0.02).
response rate). Participants completed the Overall, in Study 2 we provided
Speciesism Scale but were not informed further psychometric support for our
about the follow-up study. Other filler Speciesism Scale, finding excellent fit for
measures were included to distract from our model in an independent data sample
the speciesism items. and finding good test-retest reliability
In the second stage four weeks later, over time. Of course, the results from
all 677 participants were contacted again Study 2 cannot show that speciesism is a
with information about the retest study. result of similar psychological processes
333 US American participants (164 female; to other forms of prejudice, only that
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 14
speciesism can in fact be considered a factor analyses yield a generalized
stable and measurable attitude like racism prejudice factor explaining 50% to 60% of
and sexism. In Study 3 we turned to look the variance in different forms of
at how similar speciesism is to other forms prejudice (Ekehammar & Akrami, 2003). If
of prejudice in terms of content. speciesism is indeed to be usefully
considered a form of prejudice, people
who hold stronger speciesist attitudes
Study 3. Convergent Validity
should also exhibit other prejudicial
In Study 1 we developed a new and attitudes.
reliable scale to measure speciesism, and Our second aim—Aim IIb—is a result
in Study 2, we confirmed that speciesism of the reasoning, as suggested by the SD-
scores were persistent over time. HARM model (Dhont et al., 2016), that if
Combined, the results of Studies 1 and 2 speciesism is a form of prejudice it should
highlight that speciesism is a stable share psychological roots with other
psychological construct. Having met our forms of prejudice. In this way, we hoped
first aim—to develop a reliable and valid both to further validate the Speciesism
scale to measure speciesism—we next Scale by showing it to be correlated with
turned to our second aim: to better social dominance orientation and related
understand the nature of speciesism by socio-ideological constructs, as well as
looking at what other attitudes speciesism providing independent support for the
is associated with, and which more claims of the SD-HARM model.
general psychological orientations drive As a third and more exploratory
such speciesist attitudes. By doing so we aim—Aim IIc—, we aimed to investigate
sought to establish convergent validity of the relationship between speciesism with
the Speciesism Scale. empathic concern and actively open-
In Study 3, equipped with our new minded thinking. A previous study has
scale, we explored whether speciesism already identified a relation between
might usefully be described as a form of empathy levels and attitudes to animals
prejudice by shedding light on the (Taylor & Signal, 2005) and as such we
relationship of speciesism with other hypothesized that people higher in
psychological constructs. We took a two- empathic concern would care more about
pronged approach: first, we tested the suffering of animals and subsequently
whether speciesism correlates with other endorse less speciesist attitudes. Similarly,
forms of prejudice (Aim IIa); and second, because speciesist attitudes predominate
we looked at whether speciesism, like in society, we predicted that actively
other forms of prejudice, is driven by open-minded people, people who are
socio-ideological factors such as social more willing to change their beliefs
dominance orientation or right-wing (Baron, 2000) and think beyond the
authoritarianism that maintain other currently accepted norms, are more likely
forms of intergroup conflict (Aim IIb). to endorse anti-speciesism.
Our first aim—Aim IIa—was drawn
Method and Results
from the personality approach to
prejudice, which suggests that prejudice is 257 US American participants took
typically a generalized phenomenon: a part in the study online via MTurk, and
person who is high on ethnic prejudice received $1 payment for their
will also be high on gender-based participation. Fifteen participants were
prejudice, and so on (Allport, 1954). For excluded for failing an attention check,
example, prejudice toward various targets leaving a final sample of 242 people (110
tend to be significantly correlated female; M = 36.33, SD = 11.88). With that,
age
(Akrami, Ekehammer, & Bergh, 2011), and our sample size met the recommendations
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 15
of Comrey and Lee (1992) to recruit at extent that speciesism is—as philosophers
least 200-300 participants for scale have argued it to be—a form of prejudice,
validation. Furthermore, a review of over it should be correlated with other forms of
a hundred scale validation studies prejudice. Specifically, we looked at three
revealed that the median sample size of prototypical forms of prejudice: prejudice
such studies was 121, and so with a final based on ethnic background or race
sample of 242 we were confident that our (racism), prejudice based on gender
sample size was more than adequate (sexism), and prejudice based on sexual
(Anthoine, Moret, Regnault, Sébille, & orientation (homophobia). A growing
Hardouin, 2014). body of research has suggested that
In the main part of the study, speciesism is associated with prejudice,
participants were asked to complete to the but most of this has used simple feeling
Speciesism Scale and a number of separate thermometer type questions (Dhont et al.,
scales presented in a random order, which 2014; 2016). In our study, therefore we
are discussed in turn along with their drew upon this work but relied on widely
results below. At the end of the study used and empirically validated scales.
participants responded to demographic First, to tap racism, we used the
questions including age, gender, Modern Racism Scale (McConahay, 1986).
education (six-step continuous scale from This consists of 7 items and includes items
“less than high school degree” to such as “Blacks are getting too demanding
“graduate degree”), income (10-step in their push for equal rights” (internal
continuous scale from “under $5,000 per consistency: α = .75). Second, to look at
year” to “over $100,000 per year”), and sexism we used the Modern Sexism Scale
whether they are vegetarian (yes or no). (Swim, Aikin, Hall, & Hunter, 1995). This
Median education level was “attended consists of 8 items and included items
college” (M = 4.22, SD = 1.29) and median such as “Women often miss out on good
annual income level was “$25,001- jobs due to sexual discrimination” (α =
$35,000” (M = 5.22, SD = 2.34). .92). Third, to look at homophobia, we
We note that two items from the used the revised short version of the
original item pool that in Study 1 were Attitudes Toward Lesbians And Gay Men
shown not to load on the main speciesism Scale (Herek, 1998). This consists of 10
factor were included in this (and all items including “The idea of homosexual
following) studies. To ensure that our marriages seems ridiculous to me” (α =
results for the main Speciesism Scale hold .97). To the extent that speciesism is a
over and beyond the inclusion of these form of prejudice analogous to other
two items, we explored whether results kinds, speciesist attitudes should be
changed when these two items were associated with increased ethnic, gender,
added to the scale. As it did not, this issue and sexuality-based prejudice, just like
is further ignored. Due to the multiple these types of prejudice are typically
correlation analyses we conducted with associated with one another (Pratto et al.,
speciesism we relied on a Bonferroni 1994). Indeed, confirming the contention
adjusted alpha level of .006 per test (.05/9) that speciesism is correlated with other
as an indicator for statistical significance forms of prejudice, we found significant
(see Table 3 for all correlation coefficients). positive correlations of speciesism with
Prejudicial Attitudes racism (r = .32, p < .001), sexism (r = .41, p
< .001), and homophobia (r = .17, p < .001).
Our first set of measures was intended
to address Aim 2a: to what extent does Socio-Ideological Beliefs
speciesism correlate with other, Our second set of measures were
prototypical forms of prejudice? To the intended to address Aim 2b: to explore
Caviola, Everett, & Faber (2018) Journal of Personality and Social PsychologyTHE MORAL STANDING OF ANIMALS Page 16
whether speciesism, like other forms of speciesist norm. And fourth and finally,
prejudice, is driven by socio-ideological we looked at right-wing authoritarianism
factors. Four such socio-ideological factors (RWA; Altemeyer, 1988), a construct
stand out in previous research on tapping into the extent to which people
prejudice and intergroup conflict: Social adhere to established authorities and
Dominance Orientation (SDO; Pratto et conventions and their hostility towards
al., 1994); political conservatism (e.g. Jost those who do not. The scale consists of 15
et al., 2003); system-justification (Kay, & items including “The established
Jost, 2003); and right-wing authorities generally turn out to be right
authoritarianism (RWA; Altemeyer, 1988). about things, while the radicals and
We first looked at Social Dominance protestors are usually just ‘loud mouths’
Orientation (SDO; Pratto et al., 1994). As showing off their ignorance” (α = .92).
discussed above, the SD-HARM (Dhont et Results showed that, supporting
al., 2016) model posits that SDO predictions, speciesism was significantly
underpins both speciesism and human- correlated with SDO (r = .42, p < .001),
human types of prejudice, and so we political conservatism (r = .25, p < .001),
predicted that SDO would be correlated system-justification (r = .25, p < .001). The
with speciesism and that SDO would correlation between speciesism and RWA
account for the correlation between was positive, but not considered
speciesism and human-human types of statistically significant under the adjusted
prejudice. SDO was measured using the Bonferroni alpha level of .006 (r = .14, p =
SDO-6 scale (Pratto et al., 1994), which .03). People that were more speciesist
consists of 8 items including “Some were also more likely to endorse
groups of people are simply inferior to hierarchies between groups, report a more
other groups” (α = .93). Second, we looked conservative political ideology, and more
at political conservatism, which has been likely to engage in system justification.
previously found to correlate with Recall that the SD-HARM model suggests
speciesism (Dhont et al., 2016). We that SDO is the common ideological root
measured conservatism using a standard of both speciesism and human-human
measure (e.g. Graham, Haidt, & Nosek, types of prejudice. In order to test this
2009; Stern, West, Jost, & Rule, 2013; hypothesis we conducted partial
Poteat & Mereish, 2012) where correlation analyses between speciesism
participants indicated on two Likert scales and the other measures in which we
from 1 (very liberal) to 7 (very controlled for SDO. And indeed, when
conservative) the degree to which they controlling for SDO we found that all
identify as economically and socially partial correlations but sexism and
conservatives respectively. The two empathic concern became non-significant
measures were aggregated in the analysis. (Table 2).
Third, we looked at system- Empathic concern and Actively Open-
justification (Kay, & Jost, 2003), which to Minded Thinking
our knowledge has not been investigated
Finally, we addressed Aim 2c:
in the context of speciesism before. The
identifying the relation between
scale consists of 8 items including “In
speciesism and empathic concern as well
general, you find society to be fair” (α =
as actively open-minded thinking. We
.86). People who score high in system-
used the Empathic Concern scale, which
justification tend to justify and defend the
forms part of the Interpersonal Reactivity
status quo, and given that the status quo
Index (IRI; Davis, 1983) and consists of 7
places strict hierarchies amongst animals,
items such as “When I see someone being
we therefore assumed that they would
taken advantage of, I feel kind of
also be more likely to defend the current
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