Rhesus monkeys use both eye and head gaze to reallocate covert spatial attention facilitating visual perception

Area of Science:

• Primate behavior
• Cognitive neuroscience
• Evolutionary biology

Background:

• Nonverbal cues, especially eye-gaze, are crucial for social interaction.
• While primates follow head gaze, using eye-gaze alone to infer attention is debated.

Purpose of the Study:

• To investigate if rhesus monkeys can use eye-gaze cues alone to determine attention.
• To explore the role of head and eye movements in directing attention.

Main Methods:

• Used a realistic rhesus monkey head avatar with controlled eye and head movements.
• Monkeys detected a luminance change at a target LED after gaze presentation.
• Varied avatar size and eye-gaze amplitude to simulate different interaction distances.

Main Results:

• Head-gaze cues effectively directed covert attention, showing rapid, stimulus-driven orienting.
• Eye-gaze cues alone did not influence attentional shifts at standard amplitudes.
• Eye-gaze became effective in guiding attention when avatar size and eye-gaze amplitude increased (close-range simulation).

Conclusions:

• Rhesus monkeys can use eye-gaze cues to infer conspecifics' attentional targets.
• 3D animal models are valuable tools for controlled behavioral studies.
• Eye-gaze following is an ancient ability shared across Old World monkeys and apes.