Robin S.S. Kramer, James E. King, Robert Ward
Presented by:
Maeghyn Koehler and Char May Schule
Background

 "Personality traits describe the stable context-general
behavioral biases of an individuals"
 It had been shown there is a genetic heritability to
personality
 Humans show cross-cultural and cross-species
generalization of personality factors
 Socially relevant personality traits can be identified by
static non-expressive faces
 It is believed that our signal system is evolutionary
therefore we will share some traits with other primates
 Dominance is expressed by extroversion in humans
Stimuli

 Started with set of 37
photos from previous
study
 Chose photos:
 Looking straight on
 Had no facial expression
 Were cropped to only
the head and neck
 15 characteristics were
chosen
 Highest and lowest rating
of each chosen
Study 1 Methods

 Participants were presented with a high-low pair of a
characteristic and asked to choose the face that best
fit the on screen definition of a personality trait
 After the participants were asked to rate 1 (young) to
5 (old) the age of the chimpanzees
 Participants also completed a task of humans of the
same task
Study 1 Results and Discussion

 Accurate perception of "dominant" and "active"
characteristics.
 Close to significant accurary on "sympathetic."
 Poor perception of "sociable."
 Accurate estimate of chimp's age.
Characteristics relating to extraversion, and possibly
agreeableness, were accuratly perceived in chimpanzee
faces.
Class Discussion

Why do you think participants were able to accurately
identify traits of "dominance" and "active" but not the
charatertic of "sociable"?
Study 2 Methods

 Saw a single image of a chimpanzee at a time and
asked to rate 1 (very low) to 7 (very high) on the
defined characteristic
 Participants also completed the same task with
human faces
Study 2 Results and Discussion

 Ratings of dominance significantly correlated with actual
dominance.
 No significance correlations for other characteristics.
 Accuracy of dominance ratings was not affected by agerelated cues.
 No significant difference in perception of dominance of
males and females.
The characteristic of dominance was accurately assessed
even though participants were unable to compare the faces
associated with extreme personality values.
Study 3 Methods

 Participants were presented a high-low pair of
chimpanzees and asked to select the more dominant
 Each pair was of the same sex
Study 3 Results and Discussion

 Significantly accurate perception of dominance for
within-sex comparisons of males and females.
 More accuracy on perception of dominance in males
than females.
Dominance accurary was present for both males and
females.
Study 4 Methods

 Two blocks were presented: one chimpanzee and
one human
 In the chimpanzee block, high-low pairs of photos
were presented and they were asked to identify the
more dominant individual
 In the human block, high-low pairs of photos were
presented and they were asked to identify the more
extroverted individual
Study 4 Results and Discussion

 Significant accuracy of chimp dominance.
 Significant accuracy of human extraversion.
 However, there were individual differences in
performace on tasks. Particiapant scores on the
"social skills" domain of the AQ were negatively
correlated with accuracy on human discription task
but not on chimp task.
Class Discussion

Why do you think participants with higher scores on
Autism had trouble identifying human characteristics
but not with identifying chimpanzee characteristics?
General Discussion

The results demonstrate that humans can accurately
perceive charactersitics relating to extraversion in
chimpanzee faces on the basis of static, nonexpressive
cues.
Also, people can use cues in human and chimp faces to
identify those who are biased toward social activity and
dominace-related behaviors.
General Discussion

The researchers hypothsize a shared signal for personality
from the face in humans and chimpanzees on the basis of
shared evolutionary past.
Humans and chimps evolved to share aspects of a system for
communicating behavioral biases to conspecifics.
This shared system would involve shared aspects for
personality, shared links between personality and facial
morphology and shared cognitive mechanisms
for processing those links.
Confounds and Limitations

 Culture and/or personality of participant may affect
participant performance.
 Although the results demonstrate that people can
indentify links between personality and facial
morphology in humans and chimps, it is not known
wether chimps have similar abilities to process and
use these signals.
Do you think the researchers are right to assume that
chimps also have this ability? How could we test
chimpanzee ability to identify personality traits?
Class Discussion

 What are the benefits for the signal sender in this
arrangement?
 Why do you think humans are better at identifying
traits of extraversion and dominance than traits like
sociable, active or sympathetic? What's the
advantage of being able to identify these traits but
not others?