Scientists have long been measuring gaze data from human beings, studying everything from psychology to neuroscience. The adoption of eye tracking in the study of nonhuman primates is less widespread, but already some of the leading institutes in the field are testing the cognitive ability, comparative social cues and behavioral neuroscience/ecology of mans’ closest relative.
As in developmental research, nonhuman primate eye tracking measures the behavior in individuals who otherwise have difficulty communicating. Eye tracking is a unique method to study that which could not be studied before. Because of the technology, researchers can study and quantify gaze patterns and eye movements in an objective and automated way that increases reliability and reduces variability. Video-oculography (remote) eye tracking provides a more comfortable alternative to electro-oculography eye tracking (using search coils). This is especially advantageous when dealing with nonhuman primates since unobtrusive eye tracking does not jeopardize the subject’s natural behavior.
In primate research, eye tracking can be a tool to evaluate perception but also in assessing cognitive ability. Eye tracking in nonhuman primates can be used in fields relating to:
- Behavioral ecology
- Behavioral psychology
- Behavioral neuroscience
- Comparative psychology
The Primate Research Institute at Kyoto University currently uses eye tracking to study behavioral psychology in chimpanzee perception of the human face. Face scanning patterns reveal differences in social interaction, especially when comparing it to human eye tracking data. In earlier studies, the Primate Research Institute explored the understanding of social cues in conspecific and non-conspecific faces, comparing chimpanzees and humans. For more information read the case study.
Video demonstrating an eye tracking experiment at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, where members of the Primate Research Institute assisted their colleges in studying great apes.
The University of Parma used eye tracking on smaller apes to study how infant macaques understand and process social information. A screened video of an adult macaque making lip smacking gestures was presented to the infants. By measuring their eye movements, the Institute could validate earlier studies that claim infant macaques display sophisticated socio-cognitive abilities at a very young age. For more information read the case study. As for eye tracking studies on other animals, usage is still fairly novel. Eye trackers are used in ongoing studies with smaller animals, and have already been used to study canine cognitive ability.
Our range of remote eye trackers includes eye trackers for on-screen stimuli display, standalone eye trackers for studies of real-world stimuli, and eye trackers that offer a combination of both. Tobii eye trackers collect data remotely in a big “Head Movement Box” (the space in front of an eye tracker within which the participant can move without the eye tracker losing the ability to track the eyes) that allows large head movements and eliminates any need to limit the individual’s freedom. Tobii eye trackers have quick calibration features that cater to the study of animals, particularly in regard to efficiency. Standard eye trackers need to be re-calibrated whenever a subject moves out of the Head Movement Box. Tobii eye trackers, on the other hand, find the eyes directly upon re-gaze so that data collection can proceed almost instantly. This is immensely helpful when trying to keep eye tracking sessions effective and subjects motivated.
Nonhuman primate research must conform to the individuals, which means several shorter eye tracking sessions over a period. Tobii eye trackers allow calibration to be saved in between sessions for quick starts and efficiency. Customized calibration routines for nonhuman primates who have a limited attention span makes calibration fast and easy, reducing the time it takes to calibrate each subject. Bold, attention-grabbing stimuli are easy to set up using video and audio. Efficient eye tracking leads to more accurate data collection, thereby decreasing the need to exclude subjects due to poor data quality.
Tobii Studio™ Analysis Software is our standard software for eye tracking studies. Visualizations such as heatmaps, gaze plots and statistical indicators make it possible to create reports effortlessly. For other scientific software needs, E-prime and MATLAB extensions are available for Tobii along with our Software Development Kit (SDK) for full application customization.