Perception and production of speed during self-motion

When moving around an environment, different sensory channels - i.e., vision, proprioception or the vestibular system - provide us with congruent information about the amplitude, speed and acceleration of our displacements. This information is used to permanently update the representation of visual space in order to navigate efficiently in the surrounding world. When navigating in virtual worlds, however, vision often constitutes the only available sensory input. In line with this, understanding how visual information is used to estimate the speed of the relative displacements between the body and its surroundings has potential applications in the design of virtual environments.
Our goals - to investigate the perception of the speed of self-motion in realistically simulated environments. Using both behavioral and perceptual approach, we study how visual changes in the environment lead to a misperception of self-speed. Several aspects of the visual scene, i.e. contrast and size of the field-of-view, and their influence on the perceived and produced speed are explored.
Virtual environments technology is used to display realistic scenarios in which driving and walking simulations are implemented (Figure 1). Psychophysical adaptive methods allow for precise discrimination of speeds according to the manipulation of the visual scene. Behavioural measurements are recorded in real-time during driving tasks in order to investigate the changes in the produced speed induced by the experimental factors.
We showed that a realistic attenuation of contrast in a three-dimensional environment (Figure 2) leads to an overestimation of the speed of self-motion (Figure 3). This bias in the perceived speed induces the moving observer to slow down. Moreover, we found that the perceived speed of self motion reflects the influence of retinal angular velocities conveyed by either the centre or the periphery of the visual field. Finally, our results suggest that field-of-views of at least 60 degrees are advisable when speed perception relies solely on visual flow information.
Last updated: Friday, 05.10.2012