WASHINGTON — Designers of navigation systems for the visually impaired can tap new evidence of the mind’s ability to update its internal "maps" relative to the body, using audio sounds or verbal directions with equal effectiveness. The findings can foster tools that not only get people from one point to another, but also help them build better mental images of their total environment -- including important places (such as pay phones or shops) not directly in their path. The research is reported in the March issue of the Journal of Experimental Psychology: Learning, Memory and Cognition, published by the American Psychological Association (APA).
Three psychologists and a prominent geographer from the University of California, Santa Barbara and Carnegie Mellon University took 10 blindfolded, sighted participants and six blind participants to a grassy field to see how well they could walk to a target location. They learned their target location from one of two stimuli. One was an auditory 3-D stimulus at the target location, a loudspeaker playing a synthesized voice that said "Speaker 3." The other was an experimenter speaking in spatial language, with "o’clock" terminology for direction and linear feet for distance (for example, "2 o’clock, 10 feet" to walk 10 feet in a north-northeast direction). In some trials, participants were asked to walk directly to the target; in others, they walked forward from their starting point, then had to turn and walk toward the target after being tapped on the shoulder.
The main findings were two-fold. First, participants reached just about the same stopping points whether they took direct or indirect routes, evidence of "spatial updating" -- the ability to mentally keep track of the target location without concurrent perceptual information. "Once participants formed a spatial image, it stayed fixed in the environment," says co-author Jack Loomis, Ph.D., of the University of California, Santa Barbara, who also invents navigation tools for the visually impaired. "That’s different from cognition such as thoughts or daydreams, which move with us."
In the second main finding, both participant groups reached the target about equally well whether they used spatial-language or 3-D sound stimuli, indicating that once people internally represent, or encode, a location, they can update that representation using either stimulus mode.
Because the blind participants were equally capable of spatial updating using spatial language, the authors conclude that we may not need visual experience to develop spatial-updating skills. Loomis observes that the findings demonstrate a superb natural competency often taken for granted: "If you think about the high-precision computations going on in the brain," he says, "it’s really quite remarkable."
This research may advance the design of navigation systems for the visually impaired -- an ever-larger group as the population ages. Because so many of the visually impaired are elderly, they may be reluctant to try new technologies. "The challenge is to come up with devices that are easier to try out and use," says Loomis. "Technically, a spatial-language interface may be the way to go because all you need is a speech synthesizer, with no extra hardware or programming. It’s very simple and may ultimately be the best design."
Loomis et al. describe how forthcoming navigational aids use spatial language to indicate current location in terms of streets and cardinal directions. Importantly, his team’s findings suggest that spatial language also can convey information about important off-route landmarks and other points of interest -- for example, "A public phone is at 3 o’clock, 30 feet." "Our larger goal," explains Loomis, "is to not only to get people from A to B, but to help them build up larger knowledge of their environment. If each day, someone could learn one new route or new factor, in a year you have a lot of knowledge."
Because some users may still prefer audio stimuli, and it may have a slight edge in "Point A to Point B" navigation, developers also are working on audio and hybrid interfaces.
Article: "Spatial Updating of Locations Specified by 3-D Sound and Spatial Language," Jack M. Loomis, Ph.D., and Yvonne Lippa, Ph.D., University of California, Santa Barbara; Roberta L. Klatzky, Ph.D., Carnegie Mellon University; and Reginald G. Golledge, Ph.D., University of California, Santa Barbara; Journal of Experimental Psychology: Learning, Memory and Cognition, Vol. 28, No. 2.
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