Vocal and gestural responses of cross-fostered chimpanzees

Area of Science:

• Primate communication research
• Comparative psychology
• Animal behavior studies

Background:

• Cross-fostered chimpanzees exhibit unique communication behaviors.
• Understanding affective influences on primate vocalizations and sign language is crucial.

Purpose of the Study:

• To investigate chimpanzee responses (vocal and signed) to emotionally charged events announced via American Sign Language.
• To compare the likelihood and characteristics of signed versus vocal responses.
• To explore the impact of affective charge on communication patterns in chimpanzees.

Main Methods:

• Two cross-fostered chimpanzees (Tatu and Dar) were presented with positive, neutral, and negative events.
• Events were preceded by announcements in American Sign Language (ASL).
• Vocal and signed responses were recorded and analyzed over two months.

Main Results:

• The affective charge of events significantly influenced the likelihood of vocal and signed responses.
• Signed responses were more frequent than vocal responses, particularly to ASL announcements.
• Vocal responses were more common to the events themselves, with response type varying by affective charge and timing (immediate vs. anticipatory).

Conclusions:

• Chimpanzee communication, like human children's, is modulated by emotional valence.
• Signed communication appears more prominent in this context, especially for anticipatory signaling.
• Findings suggest complex cognitive and emotional processing underlying chimpanzee communication.