156 - Head Motion During Arboreal Locomotion Does Not Vary with Substrate Complexity in Capuchins

Poster Board Number: 156
There are separate poster presentation times for odd and even posters.
Odd poster #s – first hour
Even poster #s – second hour

Abstract Body : Arboreal environments are both complex and risky with substrates varying size, inclination, compliance, and continuity and arboreal animals have a high risk of injury when failure occurs. Visual feedback facilitates locomotion through these complex environments and primate visual anatomy (e.g. frontated and converged orbits) is likely adapted to arboreal habitats. Primates obtain visual feedback by centering a target on the fovea, which involves both head and eye movement. Here we hypothesize that capuchins will adjust their head motion to facilitate greater visual attention while navigating a complex substrate. To test this hypothesis, we filmed capuchin gait cycles along a simple, arboreal substrate and complex, arboreal substrate using two calibrated GoPro cameras. Videos were used to measure the timing and duration of an inferiorly-inclined head and head kinematics were calculated by tracking head landmarks across the gait cycle using DLT dataviewer. Results of a t-test show no significant correlation between the duration of head inferior inclination (i.e. looking down) and substrate complexity. Linear mixed models demonstrate no correlation between the timing of looking down and forelimb touchdown events nor is there a significant difference in head range of motion between substrate types. This likely indicates that eye movement plays a greater role in visual feedback during primate locomotion or they are relying on peripheral vision. Head movement may not be a good proxy for gaze behavior and future work should invest in gaze tracking technology.