Editorial: Walking in real and virtual environments

This special issue is devoted to understanding human movement by walking in real and virtual environments, investigating activities including obstacle avoidance, estimation of travel distance, visuomotor calibration of walking, gender differences in path integration, heading assessment in low vision and visual speed-matching on a feedback-controlled walking machine (treadmill). Whether implicitly or explicitly, every study in the issue takes a comparative approach, relating the activity in the virtual world to its counterpart in the real world, and vice versa, as without cross-validating one realm with the other it is arguably impossible to get it right. Necessarily, this is also a multidisciplinary area of research and thus, appropriately, the background of the contributors to this issue range from computer science to psychology, engineering to neuroscience, optics to ophthalmology and others. Indeed, there is as much of a goal for the issue to understand multimodal processing in human locomotion as there is to further the technology of virtual reality through its understanding, two aspects that embody the cross-disciplinary ethos of ACM TAP. The capability for a user to move around in the virtual, as in the real, world has long been a key requirement and challenge for virtual reality technologists and scientists. Full motion for navigation in virtual environments (VEs) using joy-stick, mouse or keyboard, can be effective but does not mimic important aspects of human action nor, it seems, do all graphic environments convey navigational cues equivalently. What can we learn from human locomotor movement and behavior in the real world that could yield a better interface in virtual reality (VR), and how can we use VR to improve our understanding of the former? Obstacle avoidance is no less than a requirement to our survival while moving, and thus to faithfully include it in VR requires a comparison to be made between its characteristics in VR and the real world. In Fink et al. in this issue, small but reliable differences are found in locomotor paths, as subjects’ avoided