Summary of:
Herrman, E., Call, J. Hernandez-Lloreda, M.V., Hare, B., Tomasello, M. (2007). Humans Have
Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis. Science,
317, 1360-1366.
Summary by Ashley Allen and Marisa Molina
For Dr. Mills’ Psychology 452.01 class, Spring, 2009
The article begins with speaking about the size of the human brain with comparison to that of
our nearest primate relatives, particularly chimpanzees and orangutans. The researchers reviewed
past hypotheses on how this evolution occurred. The first hypothesis that they researched was the
general intelligence hypothesis. This hypothesis stated that “larger brains enable humans to
perform all kinds of cognitive operations more efficiently that other species…” (Herrmann, Call,
Hernandez-Lloreda, Hare, & Tomsello, 2007, pp 1360). This simply means that our brains
enable us to perform various difficult tasks since we are a more complex species. The second
hypothesis mentioned, the ecological intelligence hypothesis, defines how our environment
shapes the way we think, which may influence the difference between the range of thought of
humans as compared to primates. Other researchers believe that the “especially challenging
demands of a complex social life of constant competition and cooperation with others in the
social group,” has led to the evolution of thought processes in primates (Hermann et al., 2007,
pp1360). Ultimately the cultural intelligence hypothesis is the foundation of this research study.
It accounts for the differences between the different aspects of cognition. The cultural
intelligence hypothesis explains how culture has helped develop human cognition. This
hypothesis is an extension of the social intelligence hypothesis, because “humans are not just
social, they are ultra social” (Hermann et al., 2007, pp1360).
The measure used in this study was the Primate Cognition Test Battery, which examined
the various dimensions of both physical and social cognition. The physical and social domains
were separated into different scales, which included: space, quantities, causality, social learning,
communication, and theory of mind. These each contained multiple tasks which were
administered to human, chimpanzees, and orangutan participants. On average, the humans were
2.5 years of age, and the primates were 6-10 years of age. Over 100 participants were used for
both the chimpanzee and human sample while only 32 orangutans were present in the study.
“The humans were tested on 5 days within a 2 week period, and the apes were tested on
consecutive days, averaging a total of 8 days” (Hermann et al., 2007, pp1362). A human
experimenter, who sat across from the subjects and tested the humans and apes, performed the
study. A second experimenter, present in a separate room, was responsible for viewing the
experiment and interpreting the results. Having more than one experimenter code the results of
the subjects increased the reliability of the study.
Overall the study found that both humans and chimpanzees scored higher in the physical
domain than the orangutans. Humans and chimps gave the correct answer on average 68% of the
time while orangutans scored correctly on only 59% of the tasks. Vastly different results were
found in the social cognition domain among all participants. Humans performed better than the
apes by giving an accurate response 74% of the time, whereas the apes were only correct on 33-
36% of the trials. With the results found in this study, the researchers provided, “strong support
for the cultural intelligence hypothesis that human beings have evolved some specialized socialcognitive skills for living and exchanging knowledge in cultural groups” (Hermann et al., 2007,
pp1365). The responses given by the 2.5-year old children provide us with examples that portray
how culture has played a role in human evolution. The cultural intelligence hypothesis has led us
to examine how cognition can be evaluated and how this complex concept has modeled human
nature.
I.
II.
INTRODUCTION
A. How and why have humans evolved such large brains?
1. The general intelligence hypothesis
a. With large brains humans can do numerous cognitive tasks better
than other species
2. The ecological intelligence hypothesis
a. It is the environment that humans lived in that made their cognitive
abilities evolve
3. The social intelligence hypothesis
a. With a complex social life primate cognition had to evolve.
B. The cultural intelligence hypothesis
1. What is the cultural intelligence hypothesis?
a. It is an extension from the social intelligence hypothesis
b. Humans evolved the ability to create cultural groups
i. these groups used artifacts, symbols, and social practices and
institutions.
c. Human children must learn how to participate in the cultural
groups which increases their cognitive skills
2. What does it predict?
a. In early human life before children are exposed to culture their
physical cognition should be the same as apes while their socialcultural cognition should already be “distinctly human.”
METHODS
A. Groups
1. 105 human children
a. 52 males and 53 females around 2.5 years old
2. 106 chimpanzees
a. 53 males and 53 females averaging 10 years old
3. 32 orangutans
a. 17 males and 15 females averaging 6 years old
B. Experimental Procedure
1. The Primate Cognition Test Battery (PCTB)
a. Measured physical and social cognition levels in all participants.
2. One female experimenter administered the PCTB to all participants
over a 2- week period.
3.
III.
IV.
A second observer videotaped the procedure and coded the participant’s
performance in a separate room.
RESULTS
A. Physical Domain
1. The human children and chimpanzees had around the same proportion of
correct responses while the orangutans had slightly lower scores.
B. Social Domain
1. The human children participants performed better than the chimpanzee
and the orangutan participants, and again the orangutans performed the
worst.
DISCUSSION
A. The study supported the cultural intelligence hypothesis which states that human
beings have evolved some distinct social-cognitive skills for surviving and
communicating in cultural groups.
B. Herrman et al. stated that some researchers may critique the study’s approach to
measuring social cognition in both primates and humans.
C. The PCTB can be used in future research to identify the evolution of cognitive
skills across all primate species.
Critical Review
I.
Liked
A. The same experimenter tested the participants throughout the entire
study.
B. All subjects were not informed about the tests from the test battery.
C. Other constructs that might have an influence on the results in the study
were controlled.
II.
Disliked
A. There were less orangutan participants in the study compared to both
the human and chimpanzee participants.
B. The testing time frame was not kept consistent throughout the study for
all participants.
C. Since the design of the experiment was created by humans the human
children participants had a better chance of succeeding in the tasks.
Test Questions
Multiple Choice:
1)The participants in the study consisted of:
a) humans, chimps, and bonobos
b) humans, chimps, and orangutans
c) chimps, bonobos, and orangutans
d) gorillas, orangutans, and humans
2) Which scale was not apart of the physical cognition domain?
a) space
b) quantities
c) social learning
d) causality
3) What did the Primate Cognition Test Battery (PCTB) measure?
a) social cognition
b) physical cognition
c) both a and b
d) none of the above
True or False:
4) (T/F) There was only one experimenter present in the study.
5) (T/F) The cultural intelligence hypothesis is an extension from the primate social
intelligence hypothesis.
6) (T/F) The orangutans performed better than the chimpanzees in the physical cognition
domain.
Answers:
1)B 2)C 3)C 4)F 5)T 6)F