Familiarity mediates apes' attentional biases toward human faces

Area of Science:

• Primate cognition
• Animal behavior
• Human-animal interaction

Background:

• Zoo-housed primates interact differently with familiar (zookeepers) and unfamiliar (visitors) humans.
• Understanding how primates distinguish between familiar and unfamiliar people and the underlying cognitive mechanisms is limited.

Purpose of the Study:

• To investigate whether primates (chimpanzees and gorillas) exhibit an attentional bias towards familiar human faces.
• To explore the cognitive mechanisms behind primate relationships with familiar and unfamiliar humans.

Main Methods:

• Utilized a dot-probe paradigm to assess attentional bias in chimpanzees and gorillas.
• Presented neutral and surprised facial expressions of familiar and unfamiliar humans, with and without face masks.

Main Results:

• Primates showed a significant attentional bias towards unfamiliar human faces over familiar ones when expressions were neutral (with or without masks).
• No significant attentional bias was observed when faces displayed a surprised expression.
• Apes demonstrated spontaneous categorization of humans based on familiarity.

Conclusions:

• The attentional bias towards unfamiliar faces suggests a novelty effect in primate perception of humans.
• This finding provides insight into how great apes categorize and respond to humans in their environment.