Gaze Strategies During Obstacle Negotiation in the Presence of Distractors: a Virtual Reality Based Assessment

Vision actively influences the gait, and older adults show altered visual patterns compared to their younger counterpart when approaching challenges in the travel path. Attentional distractors influence the motor strategies during obstacle crossing. In rehabilitation, treadmill and virtual reality (VR) are commonly used to train gait. The VR technology allows for repeatable, safe and full variable control tasks and is well accepted by the patients. The gaze behavior when watching at videos of a first perspective walking is similar to that adopted in the real world and the training of the gaze is effective to improve the accuracy of the gait. Therefore, the integration of the gaze monitoring in existing VR-based gait rehabilitation protocols could both give insights in the visuo-motor strategy adopted in challenging conditions and could improve the gait rehabilitation effectiveness. The research presented in this thesis consisted in the assessment of the visuo-motor strategies of young and older adults during obstacles crossing in a projected VR environment with visual distractors. The first part of the project consisted in testing a set-up allowing for such an assessment with a remote eye-tracking system. The tested remote eye-tracker was demonstrated to be reliable for treadmill walking, with gaze measurements comparable to those got for the static conditions. The second part of the project aimed at studying the effect of distractors during obstacle avoidance, by making young and older adults walking on a treadmill while navigating a purposely depicted VR world. Young and older adults showed different visual scan patterns of the scene. This study highlights the visuo-motor strategy of young and older adults in a set-up similar to those recently used in gait rehabilitation and showed that the two populations are distinguishable by the adopted visual strategy. This and further investigations are important to address better the gait rehabilitation interventions.