Sensorimotor control of complex locomotor tasks in ecological environments

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Community walking requires the skills to avoid collisions with surrounding obstacles. Collision avoidance strategies amongst pedestrians are known to be modulated by one's sensorimotor function and by factors such as the direction/speed of interferers. However, the extent to which (i) the gender and emotional gait pattern of an interferer (socio-cognitive factors) and (ii) the sex of the observer (biological factor) interact and contribute in shaping collision avoidance strategies remains unknown. In this program, how these factors impact on collision avoidance will be investigated through virtual reality-based locomotor (Project 1 & 2) and neuroimaging projects (Project 3 & 4). Objectives are to: (1) Investigate the influence of the interferer's gender, as perceived via physical appearance vs. gait movements, on collision avoidance strategies, and its possible interaction with the participants' sex; (2) Investigate the impact of emotional gait on collision avoidance strategies, and the modulatory effects of sex (participants) and gender (interferers); (3) Uncover the neural mechanisms involved in gender perception and their modulation due to appearance and biological motion information; (4) Determine the neural mechanisms underpinning the perception of emotional gait, and the modulatory effect of sex (participants) and gender (interferers). Healthy young males and females will participate. In Project 1, they will walk in a virtual environment (VE) viewed in a head mounted display equipped with an eye tracker, while exposed to virtual pedestrians (VRPs) displaying variations in gender as per their gait pattern (female, male) and physical appearance (female, male or neutral). In Project 2, participants will be exposed to male and female VRPs displaying different emotional gait patterns (happy, angry, sad, speed-matched neutral conditions). In both projects, locomotor (obstacle clearance, onset of trajectory deviation, etc.) and gaze outcomes (e.g., % fixation on body segments of VRP) will be compared across gender and/or emotion conditions and between sex groups. In Projects 3 & 4, participants' brain activity will be recorded with magnetoencephalography while seated and exposed to a VE projected on a screen. In Project 3, participants will discriminate the gender of VRPs in conditions similar to Project 1. In Project 4, they will discriminate the emotion of male and female VRPs displaying different emotional gaits. Event-related potentials (peak, latency) and coherence (connectivity analysis) in key brain areas involved in form, motion and emotion processing will be compared between conditions and groups. Results will provide visuomotor and brain mechanism perspectives on the modulatory role of sex, gender and emotions in pedestrian interactions. They will further support the development of ecologically-valid VR scenarios while providing a comparison basis for exploring changes in the control of complex walking tasks across the lifespan.