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. It seemed that the most logical way to determine the answer would be to test a person who was highly experienced with the technique, which led to the following experiment.
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 apparatus was similar to that used in Experiment 1, except that the BrailleNote Classic running Keysoft 6.11 and BGPS version 3.0 with a Magellan receiver (model IEC-529 IPX7) was placed on the participant's shoulder.
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. During each phase, a minimum of three trials were used, one being initiated from each of the three starting points.
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.