Aaron Steinfeld, Daniel Manes, Paul Green,
and David Hunter
After training, 36 drivers retrieved and entered a total of 20 destinations using an Ali-Scout navigation computer and 10 destinations using a touchscreen simulation while sitting in a vehicle mockup. Retrieval involved keying in part of the destination name, scrolling through a list of names, or some combination of those methods. Entry required keying in the destination's name, longitude, and latitude. Tasks using the real interface were performed under both dusk and nighttime lighting conditions, although the simulated interface was used only at dusk.
Some of the destination entry and retrieval times were unusually long. As a result, medians are more typical times than means (although means were used for ANOVA comparisons). Median retrieval times ranged from 0.4 to 12.0 seconds with an overall median of 6.2. Median entry times ranged from 39.5 to 67.6 seconds with an overall median of 51.5. An additional 30 to 60 seconds were required to look up coordinates in a manual. Mean times for men were 34 percent longer for retrieval and 19 percent longer for entry than mean times for women-both differences were statistically significant. The ratio of mean times for older subjects to mean times for young subjects was 2.8 for retrieval and 2.2 for entry. Performance also varied with context. For retrieval, the lighting condition was not significant but the simulated Ali-Scout took about 75 percent longer than the real Ali-Scout. For entry, times were 22 percent longer at night than at dusk, 37 percent longer using the simulated interface.
Usability problems found involve labeling of keys, the logic for shift key use, and changing fields. Key size and spacing and the lack of feedback were also concerns.
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