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