Flexibility in the use of requesting gestures in squirrel monkeys (Saimiri sciureus)

Area of Science:

• Primate cognition
• Animal communication
• Comparative psychology

Background:

• Understanding the evolution of intentional communication is crucial.
• Investigating primate gestural communication provides insights into its origins.
• Squirrel monkeys (Saimiri sciureus) are known for their complex social behaviors.

Purpose of the Study:

• To examine the intentionality and flexibility of requesting gestures in squirrel monkeys.
• To determine how human attention influences primate gestural communication.
• To investigate the role of joint attention in primate communication.

Main Methods:

• Squirrel monkeys were trained to use a requesting gesture for food.
• Human assistants varied their visual attention during trials.
• Gestural responses and "monitoring" (looking at the assistant while gesturing) were recorded.

Main Results:

• Monkeys preferentially gestured towards available food, irrespective of the assistant's gaze.
• Gesturing and "monitoring" increased when the assistant made eye contact or engaged in joint attention.
• Monkeys resumed gesturing and increased "monitoring" when the assistant shifted attention to them.

Conclusions:

• Squirrel monkeys demonstrate flexible and intentional use of requesting gestures.
• Their gestural communication is sensitive to social cues, including human attention and eye contact.
• This study provides the first evidence of such sophisticated intentional communication in New World monkeys.