Noninvasive telemetric gaze tracking in freely moving socially housed prosimian primates

Abstract

Behavioral and neurophysiological studies strongly suggest that visual orienting reflects the integration of sensory, motor, and motivational variables with behavioral goals. Relatively little is known, however, regarding the goals that govern visual orienting of animals in their natural environments. Field observations suggest that most nonhuman primates orient to features of their natural environments whose salience is dictated by the visual demands of foraging, locomotion and social interaction. This hypothesis is difficult to test quantitatively, however, in part because accurate gaze-tracking technology has not been employed in field studies. We here report the implementation of a new, telemetric, infrared-video gaze-tracker (ISCAN) to measure visual orienting in freelymoving, socially-housed prosimian primates (Lemur catta). Two male lemurs tolerated the system at approximately ¼ body weight, permitting successful measurements of gaze behavior during spontaneous locomotion through both terrestrial and arboreal landscapes, and in both social and asocial environments.

Following gaze: gaze-following behavior as a window into social cognition

“…Similarly, novel monitoring techniques (e.g. Shepherd and Platt, 2006) have made it possible to record subtle use of conspecific gaze cues during naturalistic interaction among ringtailed lemurs, who, like all prosimian primates, were not previously known to follow gaze (Shepherd and Platt, 2008) (Figure 3). …”

Development of a head-mounted, eye-tracking system for dogs

“…The study of the eye movements of freely moving lemurs has been facilitated by the use of a head-mounted, video-based, eye-tracking system adapted from equipment designed for human use (Shepherd and Platt, 2006). This system comprised two small cameras, one recording the visual scene, the other imaging the eye via a reflection from a dichroic mirror.…”

“…In addition, calibration can be conducted quickly, which is highly beneficial when working with non-verbal subjects. Monocular systems have been commonly used to study natural vision in humans navigating through the environment (Cheong et al, 2008) and when looking at more detailed stimuli such as faces (Kleinhans et al, 2008), as well as in non-human animals (Shepherd and Platt, 2006).…”

“…This may reflect the more standardised calibration procedure employed in the current study. The calibration cross enabled standardisation of the distance between both the calibration points and the subject and the distance between the points themselves, whilst Shepherd and Platt (2006) calibrated their equipment with a trainer holding treats entering the visual scene and standing at the five calibration locations, permitting less standardisation of distances. Whilst the current technique provides less spatial accuracy than that provided by the scleral search coil technique employed by Guo et al (2003) in primates, which achieved an accuracy level under 1°, the current technique permits investigation in more naturalistic settings, allowing movement of both head and body, as well as avoiding the surgery required to implant a coil into the eye of a non-human species.…”

Measuring and tracking eye movements of a behaving archer fish by real-time stereo vision

“…Measurements of torsional eye movements require the attachment of two or more markers on the animal eye (Migliaccio et al, 2005;Nakayama, 1974). Although such a method has previously been applied in freely moving monkeys (Shepherd and Platt, 2006), it is not suitable for freely moving smaller animals due to the relatively large size of the eye tracking system. For small marine animals, the problem is exacerbated by the nature of their habitat-water, i.e., measurements have to be acquired in an aqueous medium.…”