Traditionally, perceptual research has been compartmentalized into distinct and isolated categories according to individual modalities (i.e., visual, auditory, haptic, proprioceptive, vestibular, etc.).  This modular approach has treated individual sensory and motor processing as involving largely independent systems.  However, recently investigators are recognizing the importance of understanding cross-modal interactions and how they relate to perception and behaviour.

Much of the multisensory research up until this point has focused upon tasks involving discrete stimulus presentations in near body space. Such cue interactions of interest have included: visual-auditory integration, visual-proprioceptive integration, or visual-haptic integration. It is important, however, to investigate multisensory integration from the perspective of large-scale self-motion through action space. Unlike traditional approaches to examining the integration of two specific cues at a particular instance in time, navigating through one’s environment requires the dynamic integration of several cues across space and over time (i.e., visual flow, lower-limb proprioception, and vestibular information).  Understanding the principles underlying multimodal integration in this context of unfolding cue dynamics is very important as it provides insight into an important category of multisensory processing.

◘ Multi-sensory integration in the estimation of distance traveled
◘ Contribution of inertial information to the perception of walking speed
◘ Perception of visual speed while walking
◘ Adaptive treadmill control
◘ Vestibular perception is slow
◘ Perceived object stability
◘ Shape from shading

Perception of visual speed while walking

Every time we move through our environment, our own movements make the image of the world move on our retinae. In addition, moving objects produce retinal image motion as well (provided we don’t follow them with our eyes). How does our brain know which retinal image motion is produced by our own movements and which by actual motion of objects in the world around us? Does the perceived speed of moving objects change when we walk, compared to when we’re standing still? According to recent studies, perceived visual speed slows down when we walk (Durgin et al., 2005). This has been explained as an adaptive change in speed coding, caused by an automatic subtraction of part of the walking speed from the retinal image speed (Durgin & Gigone, In press). Currently, we are studying how general this phenomenon is. First results suggest that the reduction in perceived speed during walking may depend on the visual speed itself: it seems to be stronger with slower visual speeds. Our aim is to investigate this phenomenon more extensively and to describe the findings in a quantitative model, incorporating the different sensory signals that may play a role (visual, vestibular, proprioceptive, motor commands).

REFERENCE
◘ Durgin, Frank H., K. Gigone, R. Scott (2005): Perception of visual speed while moving. Journal of Experimental Psychology: Human Perception and Performance, 31(2), 339-353.

◘ Durgin, Frank H., K. Gigone (In press): Enhanced optic flow discrimination while walking: contextual tuning of visual coding. Perception

FUNDED BY
◘ Cyberwalk, Sixth Framework Program of the European Commision FP6-511092

Participant walking on the linear
treadmill, viewing the visual motion
on a head-mounted display