The Feasibility of Non-Tangible Cuing

As mentioned in Chapter 5, there is a difference between the requirements for initiating and sustaining ambulation. Initiating ambulation requires a single cue at the subject's feet; sustaining ambulation requires a series of cues stretching out in front of the subject.

It is clearly possible to produce initiation with non-tangible cues, using both a VV Sport display or a laser pointer.

As discussed in Subsection 6.3 below, the vertical field-of-view of the VV Sport did not seem to be adequate for smooth sustained ambulation in the trials with T.R. In these trials, the laser pointer seemed to result in a more sustained gait, in the absence of distractions. However, this result is difficult to interpret, since the laser pointer was used after the VV Sport, and T.R.'s gait changed dramatically over the course of the trials. We did not attempt to elict the behavior of stepping toward a distant stimulus using the VV Sport display.

D.L. could initiate and sustain ambulation without medication or visual cues, although with a shorter than normal stride length. Both the VV Sport display and the laser pointer resulted in an increased stride length.