Discussion of Quantitative Experiment

The quantitative study revealed an 8.2% increase in stride length using the laser pointer and a 6.4% improvement using the VV Sport display for the subject tested, based on two trials analyzed per condition.

The walkway used during the experiment contained a force plate which provided a very definite visual cue. It is reasonable to think that this improved the ``untreated'' case, resulting in a smaller improvement than would have been expected otherwise.

The subject, D.L., has typical Parkinson's disease symptoms with mild akinesia. Given that T.R. and D.L. both showed improvements in gait length using both the laser pointer or the VV Sport display, it is reasonable to believe that these results will generalize to other akinetic subjects. However, the percentage improvement is likely to vary considerably if other subjects are run. In particular, if we had done a quantitative study of T.R., the improvement from a festinating gait of 3-4 inches per step to a fairly normal initiation step would have been an order of magnitude larger than that seen for D.L.

The most important result of the quantitative study is that the apparent improvement in stride length seen in the qualitative studies can (within the limitations of a small sample size) be confirmed using rigorous measurement techniques.