Estimating Time to Contact in Virtual Reality: Does Contrast Matter?

Virtual reality (VR) is increasingly used in the research of pedestrian behavior. At the same time, empirical evidence suggests that perceptual processes in VR may deviate from real world. Such perceptual biases may affect the estimation of the time until a moving object reaches an observer (time to contact, TTC) - a parameter which is crucial to collision avoidance in the frequent use case of pedestrian street crossing. While several factors appear to influence TTC estimates, the present study focused on the effects of reduced visual contrast and a potential interaction with speed effects. In a virtual street environment, participants indicated the moment at which they expected an approaching vehicle to pass them. In line with earlier findings, TTC estimates tended to increase at higher speed, whereas effects of contrast were insignificant. While also the interaction term turned out insignificant, the descriptive data suggest that limited visibility at large distances should be considered in the context of speed effects. Questionnaires revealed that estimation accuracy was related neither to the feeling of presence, nor to the participants’ assessment of their own performance.