Behavioral and neurophysiological studies suggest that visual orienting reflects the integration of sensory, motor, and motivational variables which depend on behavioral goals. Relatively little is known about the behavioral goals governing visual orienting in natural conditions, in part because accurate gaze-tracking technology has not been employed in field studies. To address this issue, we have implemented a telemetric infrared video gaze-tracking system (ISCAN) to record overt visual orienting in primates moving freely in naturalistic environments.
In one set of experiments, we have begun to measure visual orienting in medium-sized prosimian primates at the Duke University Primate Center. In these studies, a single lemur subject has been trained to wear the gaze-tracking device while freely moving through a relatively large 3-dimensional environment. The first video shows the
subject animal licking his foot and then leaping to a box on the wall of the enclosure.
The next two video clips display the scene visible from the lemur's head, with the crosshair indicating direction of gaze. In these clips, the animal attempts to avoid his handler by leaping through a small window separating halves of the enclosure. The first of these two clips is in
real-time, while the second is
slowed for clarity: Note the extent to which gaze predicts the lemur's route through its environment. These experiments provide the first measurement of visual orienting in a freely-moving animal, as well as the first quantitative measurements of the eye movements of Lemur catta.
