The difficulty stemmed from the participants' expectation that the BGPS heading function is based on a compass.
The participants were rotated between the use of the BGPS and the starting position on the carpet squares.
Since Experiment 1 demonstrated that the participants were highly successful in locating a 25-foot-diameter circle, the next logical question appeared to be how accurately someone could use geotracking and the BGPS.
He is one of the authors of this article, was the developer of the geotracking technique, is a dog guide user, is 62 years of age, has an acquired vision loss, is functionally blind, and has more than three years of experience using the BGPS.
The experiment used an A-B-A-B single-subject design, in which the A phases represented those in which the participant used only his natural skills (no GPS) and the B phases represented those in which he used the BGPS.
After ensuring that the BGPS was working properly, the participant was taken to the selected starting point, but no sound cues were provided at the target point.
Training was aimed at teaching the functions required of the BGPS that are required to help a user reorient herself when lost and to locate a given target house in a familiar neighborhood.
After a participant demonstrated a complete knowledge of the names of the streets and the street-numbering system in the neighborhood, she was randomly assigned to either the BGPS or no-BGPS condition.
Figure 1 presents the data regarding the three participants and graphically demonstrates the effect of BGPS on reorientation.
Note that on the graph, the level or relative height of the BGPS line for all the participants is higher than the no-BGPS line, demonstrating an increased efficiency rate of finding the target location.
The participant was also one of the designers of the study because he was the only sufficiently skilled BGPS user in the geographic region and was highly familiar with the study area.