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No one alike - "personality" differences in the
great apes
Press release in PDF-Version
Great apes are human's closest living relatives. Their cognitive
abilities have been investigated and compared to those of humans for
a long time. But so far, researchers have largely ignored the
pronounced individuality of great apes and have dismissed them as
purely anthropomorphic ideas. At the Max-Planck-Institute for
Evolutionary Anthropology in Leipzig, Jana Uher developed new
research methodologies and approaches to explore the pronounced
individual differences in the great apes. Her comprehensive studies
in the Leipzig Zoo systematically demonstrate individual-specific
behaviours - i.e., "personality" differences - in the the great
apes.
(© Photos: MPI-EVAN & Jana Uher, Primate Personality
Net, MPI-EVAN & Humboldt University Berlin)
The great apes are human's closest living relatives. Pioneers of
primate research such as Wolfgang Köhler and Robert Yerkes had
already reported observations about the pronounced individuality in
these species some 100 years ago. But the scientific exploration of
individual-specific peculiarities or even their labelling as
"personality" differences have been dismissed as purely
anthropomorphic ideas.
Therefore, Jana Uher has developed novel methodologies and research
approaches to systematically investigate and categorise
individual-specific patterns in behaviour, that is, "personality"
differences - not only in humans, but in nonhuman species as well.
She applied these novel methodologies exemplarily for the first time
in studies on great apes. At the
Wolfgang Köhler
Primate Research Centre of the
Max Planck
Institute for Evolutionary Anthropology and the
Leipzig Zoo, Germany, she studied 20 great ape individuals -
bonobos, chimpanzees, gorillas and orangutans. She observed these
individuals in their groups prior to their noon feeding and during
the afternoon. She also developed 14 different behavioural tests in
which she recorded the great apes' behaviours, which she coded later
using a special kind of software. These detailed and comprehensive
recordings of individual behaviour in various situations on 76
behavioural variables overall enabled illuminative analyses. It was
thereby essential that the researcher conducted all behavioural
tests and observations repeatedly and in two separate time periods
each consisting of 14 days. Overall, she recorded the behaviours of
a single individual for over 67.3 hours. These comprehensive data
sets allowed her to explore whether individual differences occurred
only by chance or if great apes do, in fact, show stable individual
differences in their behaviours that are specific to the individuals
- because only such differences are called "personality"
differences.
To investigate explorative behaviours, the apes were given small
novel objects (Novel object test;
Uher et al., 2008, p. 103). Some individuals
immediately took the objects and explored them for quite a while.
Similar to young children, great apes investigate novel objects
frequently with their mouths - orangutans also like to additionally
use their prehensile feet for exploring objects. Some individuals
also played with them intensely and quite innovatively. Other
individuals, in turn, put the objects down in a corner fairly soon
or did not even pick them up at all, but observed them from a secure
distance for a long time.
(© Photos: Jana Uher, Primate Personality Net,
MPI-EVAN & Humboldt University Berlin)
Some other tests studied how individuals respond to a pile of
food or a banana in full view and almost in reach (Food out of reach
test, Pile of food test;
Uher et al., 2008, p. 103). Some individuals got
quickly excited and, for example, vocalised or scratched a lot,
whereas other individuals waited calmly and hardly showed any signs
of arousal. Left picture: The actual test candidate Viringika is
sleeping underneath the table, while her two-year-old daughter
Kibara is sitting on her and cannot stop looking at the banana-just
like Fraukje at the sight of the pile of fruit (right picture).
(© Photos: Jana Uher, Primate Personality Net, MPI-EVAN
& Humboldt University Berlin)
To investigate explorative behaviour, the apes were also given
coloured pieces of food, such as apple slices, that were shaped in
different ways (Novel food test;
Uher et al., 2008, p. 103). The responses were
very different. Some apes investigated the novel food intensely,
played with it, and tasted and ate it. Others, in turn, completely
ignored the strange looking items or immediately threw them back to
the experimenter.
(© Photos: Jana Uher, Primate Personality Net, MPI-EVAN
& Humboldt University Berlin)
The apes' vigilance was investigated in the Hidden food test (Uher
et al., 2008, p. 102) in which small pieces of food were hidden
in the cage of the apes who did not know about this, such as small
raisins (left photo) or a small dot of honey smeared at the coloured
wall (right photo). Some individuals quickly spotted the sweet
surprises, whereas it took others a long time to notice them - if
they found the items at all.
(© Photos: Jana Uher, Primate Personality Net, MPI-EVAN & Humboldt
University Berlin)
How persistently great apes can deal with a task even in absence
of a reward, was studied in the Button-box Test (Uher
et al., 2008, p. 101). After two trials in which only four
buttons were presented and pressing a button was always rewarded,
the apes got access to 20 buttons, but were not rewarded any more
for pressing buttons. Some individuals continued pressing the
buttons (left), whereas others made themselves comfortable in a nest
and pressed the buttons just here and then (right).
(© Photos: Jana Uher, Primate Personality Net,
MPI-EVAN & Humboldt University Berlin)
(© Graphic: Jana Uher)
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These results demonstrate that the great apes show stable
individual differences across a broad range of behaviours. The
individual constellations of specific behavioural tendencies were
also stable over time; they can be illustrated in "personality"
profiles. For example, the combination of stable individual
patterns in different behaviours of the chimpanzee female Sandra
was remarkably similar in both periods of investigation (compare
the continuous and broken profile lines in the figure)-this stable
individual behavioural profile visually represents the scientific
measurement of Sandra's "personality" across the entire time
period of the study. |
This research was awarded several prizes for outstanding research.
Contact person: Dr. Jana
Uher
Scientific publications:
Uher, J., Asendorpf, J. B., &
Call, J. (2008). Personality in the behaviour of great apes:
Temporal stability, cross-situational consistency and coherence in
response. Animal Behaviour, 75, 99-112.
https://doi.org/10.1016/j.anbehav.2007.04.018
[Download]
[Highlights]
Uher, J. (2011b). Personality in nonhuman primates: What can we
learn from human personality psychology? In A. Weiss, J. King, & L.
Murray (Eds.). Personality and temperament in nonhuman primates
(pp. 41-76). New York, NY: Springer.
https://doi.org/10.1007/978-1-4614-0176-6_3
[Download]
[Highlights]
Uher, J. (2008a). Comparative personality
research: Methodological approaches [Target article]. European
Journal of Personality, 22, 427-455.
https://doi.org/10.1002/per.680
[paper request]
[Highlights]
Uher, J. (2008b). Three methodological core
issues of comparative personality research. European Journal of
Personality, 22, 475-496.
https://doi.org/10.1002/per.688 [paper
request] [Highlights]
Uher, J. & Asendorpf, J. B. (2008). Personality
assessment in the Great Apes: Comparing ecologically valid behavior
measures, behavior ratings, and adjective ratings. Journal of
Research in Personality, 42, 821-838.
https://doi.org/10.1016/j.jrp.2007.10.004 [Download]
[Highlights]
Last update 14.09.2013
Keywords: Pan paniscus, Pan troglodytes, Gorilla gorilla, Pongo
pygmeus, individual differences, personality, judgment, rating,
assessments, personality questionnaire, behavioural profiles,
personality rating, chimpanzee, bonobo, gorilla, orangutan, great
apes, primates.
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