Identifying personality from the static, nonexpressive face in humans and chimpanzees:
evidence of a shared system for signaling personality
Robin S.S. Kramer, James E. King, Robert Ward
Presented by:Maeghyn Koehler and Char May Schule
"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
Background
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
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 Methods
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.
Study 1 Results and Discussion
Why do you think participants were able to accurately identify traits of "dominance" and "active" but not the charatertic of "sociable"?
Class Discussion
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 Methods
Ratings of dominance significantly correlated with
actual dominance. No significance correlations for other characteristics. Accuracy of dominance ratings was not affected by
age-related 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 2 Results and Discussion
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 Methods
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 3 Results and Discussion
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 Methods
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.
Study 4 Results and Discussion
Why do you think participants with higher scores on Autism had trouble identifying human characteristics but not with identifying chimpanzee characteristics?
Class 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.
General Discussion
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?
Confounds and Limitations
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?
Class Discussion