CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE
In a recent article in the Los
Angeles Times, Robert Fagen, a
professor of biometry, described
Susie as irascible, irritable, grumpy,
and manipulative. This is hardly
newsworthy, except that Susie is a
bear. Scientists have been reluctant
to ascribe personality traits, emotions,
and cognitions to animals,
even though they readily accept
that the anatomy and physiology of
humans is similar to that of animals.
Yet there is nothing in evolutionary
theory to suggest that only
physical traits are subject to selection
pressures, and Darwin
(1872/1998) argued that emotions
exist in both human and nonhuman
animals. Thus, personality
traits like Extraversion and
Agreeableness may not be as
uniquely human as once was
thought (Buss, 1988). Early attempts
to assess animal personality,
including the pioneering studies
by Stevenson-Hinde, were conducted
in the 1970s, and the 1990s
have seen a resurgence of research
activity. Our goal in this article is to
take stock of what is known about
animal personality, focusing on individual
differences within species.
We ask, What are the major dimensions
of animal personality?
Faced with the challenge of integrating
the fragmented literature
on animal personality, we felt like
early cartographers faced with the
challenge of constructing a map of
the globe. Our task--much like that
of the cartographers--was to piece
together the isolated reports about
the landscape of personality. These
reports came in different languages;
used a variety of scales,
methods, and notations; and varied
in their scope and reliability. Our
first task was to select the most
trustworthy reports; starting with
more than 100 potentially relevant
studies, we selected those that had
sample sizes larger than 20 animals
and a reasonably broad coverage of
personality traits.2
To integrate the many pieces of
information provided by the diverse
research reports, we used the
most widely accepted and complete
map of personality structure:
the human Five-Factor Model
(FFM; John, 1990). The FFM is a hierarchical
model with five broad
factors (Table 1), which represent
personality at the broadest level of
abstraction. Each bipolar factor
(e.g., Extraversion vs. Introversion)
summarizes several more specific
facets (e.g., sociability), which, in
turn, subsume a large number of
even more specific traits (e.g., talkative,
outgoing). Unfortunately, no
short labels capture the broad FFM
dimensions adequately, so the traditional
labels are easily misunderstood;
thus, we use the letters N
(for Neuroticism, Nervousness,
Negative affectivity), A (for Agreeableness,
Altruism, Affection), E
(for Extraversion, Energy, Enthusiasm),
O (for Openness, Originality,
Open-mindedness), and C
(for Conscientiousness, Control,
Constraint).
Are there additional dimensions
that might be of special importance
for describing the personality of
nonhuman animals? In adult
human personality, Activity and
Dominance are part of the E dimension.
In children, however, Activity
may form a separate dimension
(John, Caspi, Robins, Moffitt, &
Stouthamer-Loeber, 1994), and
temperament models (Buss &
Plomin, 1984) also consider it separate.
Moreover, many socially living
animal species show individual
differences related to status in the
dominance hierarchy: Individuals
with high status can control others
MAPPING THE LANDSCAPE
OF ANIMAL PERSONALITY
Copyright  1999 American Psychological Society 69
Personality Dimensions in Nonhuman
Animals: A Cross-Species Review
Samuel D. Gosling1 and Oliver P. John
Institute of Personality and Social Research, University of California, Berkeley,
Berkeley, California
Abstract
The evolutionary continuity
between humans and other
animals suggests that some
dimensions of personality may
be common across a wide
range of species. Unfortunately,
there is no unified body of
research on animal personality;
studies are dispersed
across multiple disciplines and
diverse journals. To review 19
studies of personality factors
in 12 nonhuman species, we
used the human Five-Factor
Model plus Dominance and
Activity as a preliminary
framework. Extraversion, Neuroticism,
and Agreeableness
showed the strongest crossspecies
generality, followed by
Openness; a separate Conscientiousness
dimension appeared
only in chimpanzees,
humans' closest relatives.
Cross-species evidence was
modest for a separate Dominance
dimension but scant for
Activity. The comparative
approach taken here offers a
fresh perspective on human
personality and should
facilitate hypothesis-driven
research on the social and
biological bases of personality.
Keywords
personality; traits; crossspecies;
Big Five; temperament
70 VOLUME 8, NUMBER 3, JUNE 1999
and get their way. To explore
whether Activity and Dominance
form separate dimensions in animals,
we added them to the five
FFM dimensions in our preliminary
framework (see Table 2).
Our review includes 19 factor
analytic studies and represents 12
different species. We reviewed the
items defining each personality factor
in each study and compared
them with the definitions of the
seven potential dimensions in
Table 2. If there was a match in item
content, we classified the animal
factor into one of the seven dimensions
and included its label (or a
short definition) in the appropriate
column of Table 2.3
Extraversion, Neuroticism, and
Agreeableness: Cross-Species
Dimensions?
Three human FFM dimensions--E,
N, and A--showed considerable
generality across species.
Of the 19 studies, 17 identified a
factor related to E. The factor labels
in the E column in Table 2 range
from Surgency in chimpanzees to
Sociability in pigs, dogs, and rhesus
monkeys; Energy in cats and
dogs; Vivacity in donkeys; and a
dimension contrasting Bold
Approach versus Avoidance in octopuses.
The particular labels may
differ, but they all reflect core features
of the broad E dimension (see
Table 1). Factors related to N appeared
almost as frequently; again,
despite the differences in factor labels,
these animal factors capture
core elements of N, such as
Fearfulness, Emotional Reactivity,
Excitability, and low Nerve
Stability. Factors related to A appeared
in 14 studies, with
Affability, Affection, and Affinity
capturing the high pole of A, and
Aggression, Hostility, and Fighting
capturing the low pole.4
The evidence indicates that
chimpanzees, various other primates,
nonprimate mammals, and
even guppies and octopuses all
show individual differences that
can be organized along dimensions
akin to E, N, and (with the exception
of guppies and octopuses) A.
These remarkable commonalities
across such a wide range of taxa
suggest that general biological
mechanisms are likely responsible.
The way these personality dimensions
are manifested, however, depends
on the species. For example,
whereas the human scoring low on
Extraversion stays at home on
Saturday night, or tries to blend into
a corner at a large party, the octopus
scoring low on Boldness stays in its
protective den during feedings and
attempts to hide itself by changing
color or releasing ink into the water.
Openness: Another Potential
Cross-Species Personality
Dimension?
Factors related to the O dimension
in the FFM were identified in
7 of the 12 species. The two major
components defining this dimension
were curiosity-exploration
(interest in new situations and
novel objects) and playfulness
(which is associated with E when
social, rather than imaginative, aspects
of play are assessed).
Although these factors are similar
to the O dimension known from
humans, some core facets are obviously
missing; openness to ideas
and interest in arts are difficult to
observe in animals that lack advanced
means of symbolic expression,
such as language and music.
The O factor in these animal studies
resembles the early forms of O
observed in human toddlers; lacking
advanced language skills, their
curiosity is manifested in an intense
interest in novel objects and
events, and their imagination is
shown in perspective taking and
role shifts characteristic of pretend
play.
The evidence for an O-related
factor was not consistent across
multiple studies of the same
species, pointing to methodological
differences, most likely in the
traits included in the studies. For
example, the two chimpanzee
studies that did not find an O factor
did not include items clearly
relevant to O. Given that forms of
curiosity have been observed in a
wide range of species, a thorough
and focused search should provide
more consistent evidence for
O.
Published by Blackwell Publishers, Inc.
Table 1. The dimensions of the Five-Factor Model (FFM)
FFM dimension label Examples of facets
N Neuroticism vs. Emotional Stability Anxiety, depression, vulnerability to stress, moodiness
A Agreeableness vs. Antagonism Trust, tendermindedness, cooperation, lack of aggression
E Extraversion vs. Introversion Sociability, assertiveness, activity, positive emotions
O Open vs. Closed to Experience Ideas/intellect, imagination, creativity, curiosity
C Conscientiousness vs. Impulsiveness Deliberation, self-discipline, dutifulness, order
Note. See John (1990) and Costa and McCrae (1992) for details.
CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 71
Conscientiousness: Only in
Humans and Chimpanzees?
Although cats and dogs showed
a factor that combined C and O,
chimpanzees were the only species
with a separate C factor. The chimpanzee
factor was defined more
narrowly than in humans but included
lack of attention and goal
directedness, as well as erratic, unpredictable,
and disorganized behavior--characteristics
typical of
the low pole of C. Why did we not
find separate C factors in any other
species? The failure to include relevant
items cannot explain this finding:
In our own studies of dogs and
cats, we included items that define
C in humans, but they did not form
a separate factor. Considering the
"superego" aspects of the C factor
(following norms and rules, thinking
before acting, and other complex
cognitive functions involved
in the control of impulses), it may
not be surprising that we found a
separate C factor only in humans
and in humans' closest relatives,
chimpanzees. These findings suggest
C may have appeared relatively
recently in the evolution of
Homininae, the subfamily comprising
humans, chimpanzees, and
gorillas.
Dominance and Activity: Two
Additional Dimensions?
Dominance emerged as a clear
separate factor in 7 of the 19 studies.
Although interpreted as
Confidence in rhesus monkeys
and Assertiveness in hyenas, the
factor was essentially the same,
correlating substantially with
dominance rank.5 Across studies,
the Dominance factor was typically
defined by assertiveness or
boldness (high E), physical aggression
(low A), and low fearfulness
(low N). Thus, dominance had
more diverse personality implications
in animals than in humans,
for whom it is related only to the E
dimension. Perhaps these differences
arise because humans participate
in multiple dominance hierarchies
that are less clearly defined
and involve widely divergent
skills: The class bullies may dominate
in the school yard, but the
conscientious students will get the
grades to advance academically,
and the open-minded artists will
win prizes for their creations.
Future research needs to examine
more closely the links between
dominance rank and personality
traits. Personality may vary even
among animals of the same rank,
and rather than being viewed as a
personality trait, dominance rank
may be better conceived as a social
outcome determined by both personality
and physical traits (Buss,
1988).
Finally, our review uncovered
scant evidence for the idea that
Activity should be retained as a
separate dimension of animal personality,
with only 2 of the 19 studies
showing support. Of the 3
chimpanzee studies, only the study
of infants identified a separate
Activity factor. This age difference
in chimpanzees parallels findings
in humans suggesting that Activity
may not become integrated with
the E dimension until late adolescence
(John et al., 1994).
A number of the studies summarized
in Table 2 relied on human
observers rating animals on trait
adjectives defined in brief behavioral
terms (e.g., playful was defined
as "initiates play and joins in
when play is solicited"). Although
some researchers argue that observer
ratings are the best way to
assess personality, others are skeptical
and worry that these ratings
might be anthropomorphic projections.
Three kinds of evidence
argue against this concern. First,
for a wide range of species, including
chimpanzees, rhesus monkeys,
and hyenas, studies show that independent
observers agree about
the relative ordering of individuals
on a trait. Second, many of the
studies reviewed here used behavioral
tests in specific situations or
carefully recorded ethological observations.
Both types of data
yielded similar factors. For example,
when piglet behavior was tested
in specific situations, the E factor
was defined by number of
vocalizations, number of nose contacts,
and location in the pen; when
chimpanzee behavior was observed
in naturally occurring settings,
the E factor was defined by
behavior patterns such as "pull
limb" (playful social contact),
"grasp and poke" (boisterous but
relaxed contact), and "gymnastics"
(exuberant locomotory play, such
as swinging, dangling, turning
somersaults). It is remarkable that
such similar factors were discovered
using such diverse methods.
In fact, studies using multiple
methods have demonstrated the
validity of trait ratings (Capitanio,
1999). Third, our finding that the
factor structures showed meaningful
differences across species argues
against the operation of general
rating biases in observers. For
example, in our own work, we
found the familiar FFM dimensions
for humans but only four factors
for dogs, even when we collected
personality ratings using the same
instrument for both species; the
items defining a clear C factor in
humans failed to form a separate
factor in dogs (Gosling & John,
1998). These differences show that
personality structure depends on
the individual rated, rather than on
the particular items in the rating
instrument.
Sex differences are another domain
where cross-species differences
in the meaning and implications
of personality factors can be
THE SPECTER OF
ANTHROPOMORPHISM
Copyright  1999 American Psychological Society
72VOLUME8,NUMBER3,JUNE1999
PublishedbyBlackwellPublishers,Inc.
Table 2. Review of animal personality factors: Factor labels organized in terms of the Five-Factor Model (FFM) plus two potential additional dimensions
Trait dimensions in the human FFM Additional dimensions
Species Neuroticism Agreeableness Extraversion Openness Conscientiousness Dominance Activity Study
Chimpanzee Emotional Agreeableness Surgency Openness Dependability Dominance King and Figueredo
Stability (1997)
Audiovisual Affect- Task Behavior Activity Bard and Gardner (1996)
Reactivity Extraversion
Excitability- Aggression; Social Play Submission Hooff (1973)
Agitation Affinitya
Gorilla Fearfulness Understanding Extroversion Dominance Gold and Maple (1994)
Rhesus Tense-Fearful Aggressive Solitary Curious- Bolig, Price, O Neill,
monkey Playful and Suomi (1992)
Excitability Sociability Confidence Stevenson-Hinde and
Zunz (1978); StevensonHinde,
Stillwell-Barnes,
and Zunz (1980)
Fear Hostility Affiliation Chamove, Eysenck, and
Harlow (1972)
Vervet Opportunistic Playful-Curiousb Social McGuire, Raleigh, and
monkey Self-Serving Competence Pollack (1994)
Hyena Excitability Sociability; Curiosity Assertiveness Gosling (1998)
Human-Related
Agreeablenessa
Dog Emotional Affection Energy Competencec Gosling and John (1998)
Reactivity
Stability vs. Sociability Learning and Dominance- Coren (1998)
Excitability Obedience Abilityc Territoriality
CURRENTDIRECTIONSINPSYCHOLOGICALSCIENCE73
Copyright1999AmericanPsychologicalSociety
Table 2. continued
Trait dimensions in the human FFM Additional dimensions
Species Neuroticism Agreeableness Extraversion Openness Conscientiousness Dominance Activity Study
Nerve Affability; Lively Wilsson and Sundgren
Stability Aggressiona Temperament (1997)
Aggression Reactivity Trainability Hart and Hart (1985)
(Disagreeableness) (Surgency) (Openness) (reanalyzed by Draper,
1995)
Cat Emotional Affection Energy Competencec Gosling and John (1998)
Reactivity
Donkey Obstinacy Vivacity French (1993)
Pig Aggression Sociability Exploration- Forkman, Furuhaug,
Curiosity and Jensen (1995)
Rat Emotionality Fighting vs. Billingslea (1941)
Timidity;
Freezing vs.
Aggressiona
Guppy Fear-Avoidance Approach Budaev (1997)
Octopus Reactivity Bold vs. Activity Mather and
Avoiding Anderson (1993)
Note. All studies are based on factor analyses of individual animals, except Coren (1998) and Hart and Hart (1985), who analyzed experts ratings of breeds. Several studies did not include
factor labels at all or included labels too brief to understand without further information; for these cases, we used high-loading items to help name the factors.
aThese four studies yielded two separate factors related to Agreeableness.
bThis factor combined both social and imaginative elements and thus reflects both Extraversion and Openness.
cThese factors combined elements from both Openness and Conscientiousness.
74 VOLUME 8, NUMBER 3, JUNE 1999
illustrated. Research on the human
FFM has repeatedly shown that
women tend to be more emotional
and prone to worry (i.e., higher on
N) than men (Costa & McCrae,
1992). Does the same sex difference
emerge in other species? Not
necessarily. To illustrate this point,
we collected observer ratings of
humans using items previously
used in a study of hyenas
(Gosling, 1998). In humans,
women were described as somewhat
higher on N than men; in
hyenas, the sex difference was reversed,
with males being considerably
more high-strung, fearful,
and nervous than females (see Fig.
1). What explains this dramatic interaction
effect? The key is the difference
in social organization: In
the hyena clan, dominance rank is
transmitted through a matrilineal
system, and females are larger
than males and more dominant.
This example suggests that sex differences
in personality may be related
to the ecological niches occupied
by the two sexes in a species,
and illustrates how a comparative
approach can offer a fresh perspective
on the interplay between social
and biological factors in
personality.
The cartographic metaphor
serves to highlight some limitations
of the initial map of animal
personality dimensions presented
in Table 2. First, Antarctica will be
discovered only if one sails south:
The lack of evidence for a dimension
does not necessarily prove the
factor does not exist; studies may
not have included the items relevant
for the factor. To show that a
dimension does not exist in a
species requires that future researchers
actively search for that
dimension. Equipped with our initial
map, we can now conduct hypothesis-driven
research. For example,
we may hypothesize that
solitary species (e.g., orangutans)
would not show a separate A dimension,
or that O occurs only in
species that depend on a great variety
of food sources. Second, just
as early maps look rough by
today's standards, with missing
land masses and poorly defined
boundaries, we expect that future
researchers will refine our rough
initial sketch and discover new islands,
perhaps even continents.
Third, much work remains to be
done on the internal geography of
the continents. For example, a
great many species appear to inhabit
the curiosity area of the O
continent, but other areas may be
inhabited solely by humans and
perhaps chimpanzees. Fourth, researchers
need to move from mapping
personality continents to formulating
theories about the
movements of tectonic plates, addressing
how and why the continents
emerged; animal models of
personality may be uniquely suited
to identify genes for complex traits
and to study how these genes work
(i.e., functional genomics). Finally,
the early sailors knew their maps
were not perfect, but imperfect
maps were better than no map at
all; it is in this spirit that we offer
the present classification of animal
personality, hoping that future researchers
may find this initial
sketch helpful in their quest for
new discoveries.
CONCLUSIONS AND
FUTURE DIRECTIONS
Published by Blackwell Publishers, Inc.
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
Human Hyena
Species
MeanNeuroticismscore
Male
Female
Fig. 1. Sex differences in standard (z) scores for Neuroticism among humans and
hyenas. The ratings for hyenas are from Gosling (1998); the humans (n = 100) were
described by peers on the same rating scales used for hyenas.
Recommended Reading
Gosling, S.D. (1998). (See References)
King, J.E., & Figueredo, A.J. (1997).
(See References)
McCrae, R.R., & John, O.P. (1992). An
introduction to the Five-Factor
Model and its applications.
Journal of Personality, 60, 175­215.
Stevenson-Hinde, J. (1983). Individual
characteristics and the
social situation. In R.A. Hinde
(Ed.), Primate social relationships:
An integrated approach (pp.
28­35). Sunderland, MA: Sinauer
Associates.
CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 75
Notes
1. Address correspondence to
Samuel D. Gosling, Department of
Psychology, University of Texas,
Austin, TX 78712; e-mail: gosling@
psy.utexas.edu.
2. A number of factor analytic studies
did not sample personality traits
broadly but focused on a single trait.
The numerous studies of emotionality
in mice are an example of this
approach.
3. There were a number of complications
due to differences in the way
factor analytic procedures are used and
reported in this literature (e.g., some
studies did not rotate factors; others
did not report factor loadings), but we
cannot discuss these complications in
the space available here. Only a small
number of animal factors could not be
classified; most of these factors would
not be considered part of personality
(e.g., physical coordination in chimpanzees
and indoor vs. outdoor suitability
in dogs).
4. Although four studies yielded
two separate factors related to A, these
findings may reflect methodological artifacts.
For example, in Wilsson and
Sundgren's (1997) study of dogs, separate
Affability (high A) and Aggression
(low A) factors were found, but
Affability was defined by only one
item. In Gosling's (1998) study of hyenas,
the two dimensions related to A
(Human-Related Agreeableness and
Sociability) were positively related.
5. Unlike all the other species reviewed,
octopuses are clearly solitary
(rather than social) and thus cannot exhibit
dominance rank.
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Acknowledgments--The preparation of
this article was supported, in part, by a
University of California, Berkeley,
Chancellor's Dissertation Fellowship to
Samuel D. Gosling and by National
Institute of Mental Health Grant 49255
to Oliver P. John. We thank George
Barlow, Sergey Budaev, Arnold Buss,
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Copyright  1999 American Psychological Society