The role of vision and biomechanics when walking over rough terrain

Abstract

In order to take action in the world, humans require coordination between per- ceptual information about the environment and the action capabilities endowed to us by the structure of our bodies. Within the context of walking, the mechanics of the human body exhibit stable gait behavior that emerges passively as a consequence of the interaction between the body and environment. While this emergent behavior is highly efficient and dynamically stable, humans require perceptual control to move through the dynamic natural world. How then is the perceptual control of locomotion organized with respect to our bipedal structure? Here I present three related studies which explore how humans use visual information about the terrain to exploit their locomotor dynamics to perform naturalistic walking tasks. These studies utilize full-body motion capture and responsive augmented reality to present naturalistic terrain and precisely measure human walking behavior in response to changes in visual information. Experiment 1 explores how humans use visual information to rapidly modify their foot placement in response to changes in the availability of footholds. Experiment 2 expands on Experiment 1 and investigates how the decisions that humans make about where to step depends on their locomotor biomechanics. Finally, Experiment 3 explores the degree to which humans can exploit their biomechanics under naturalistic constraints by capturing walking behavior as subjects traverse a field of raised obstacles. Together these studies provide convergent evidence that walking behavior in naturalistic terrain is largely organized around the emergent dynamics of our evolved biomechanical structure. They also point to a broader view of human cognition, wherein cognition serves to directly perceive and actively exploit relevant task dynamics that emerge from our interaction with the world.