Spatial Stabilization and Physical Realism

Spatial stabilization appears to be the single most critical factor for enabling kinesia paradoxa using the VV Sport display. It is necessary for the image to appear to be approximately stationary on the ground as the subject steps forward. Exact stabilization (for instance produced by using a gait tracker to control the rate at which images move down the display) was not attempted and fortunately does not seem to be essential, at least for the level of results achieved in this study. It is quite possible, however, that such precise space stabilization would produce better results than our approximate stabilization. We leave this for future research.

For T.R., at least, it is possible to switch speeds by attending to different stimuli in the VV Sport display. We did not try this experiment with D.L. By providing different stimuli concurrently, it may be possible to enable smooth transitions both between speeds and between directions.

Both T.R. and D.L. were able to improve their gait as a result of cues with a very crude appearance: simple squares or the spot of a laser pointer. This suggests that a highly realistic appearance is not crucial to kinesia paradoxa. However, actual playing cards remain a more effective (if less convenient) cue for both subjects than either the VV Sport or the laser pointer. It is to be expected, therefore, that improving the realism of non-tangible cues will increase therapeutic benefit, provided that spatial stabilization is not sacrificed.

• Virtual Vision Display Compared to Laser Pointer