Non-invasive Eye Tracking Methods for New World and Old World Monkeys

Area of Science:

• Primate behavior
• Neuroscience
• Comparative psychology

Background:

• Eye-tracking is crucial for understanding visual attention and social information processing in nonhuman primates.
• Previous methods required head restraint, limiting research scope and participant numbers.
• Altered social processing in humans (e.g., autism spectrum disorder, schizophrenia) highlights the translational potential of primate eye-tracking studies.

Purpose of the Study:

• To develop and validate a novel, noninvasive eye-tracking method for nonhuman primates.
• To overcome limitations of head-restraint methods, enabling studies in a wider range of primates and ages.
• To explore primate visual attention towards species-specific stimuli in a free-moving paradigm.

Main Methods:

• A transport box with a viewing window was modified for eye-tracking data collection.
• Data were collected from New World monkeys (Callicebus cupreus) and Old World monkeys (Macaca mulatta) at various developmental stages.
• Monkeys voluntarily viewed stimuli within the box, with no prior habituation to the eye-tracking setup.

Main Results:

• Juvenile primates exhibited greater stimulus viewing compared to other age groups.
• Video stimuli were viewed more extensively than static photographic imagery.
• Repeated eye-tracking sessions led to increased viewing duration in monkeys.

Conclusions:

• The developed noninvasive method significantly expands opportunities for eye-tracking research in nonhuman primates.
• This approach facilitates studies on social cognition and behavior without sedation or restraint.
• Findings provide a foundation for future translational research into neurodevelopmental disorders.