The Effectiveness of Verbal Information Provided by Electronic Travel Aids for Visually Impaired Persons
Havik, Else M., Kooijman, Aart C., Steyvers, Frank J. J. M., Journal of Visual Impairment & Blindness
Abstract: The effectiveness of different types of verbal information provided by electronic travel aids was studied in a real-life setting. Assessments included wayfinding performance and the preferences of 24 visually impaired users. The participants preferred a combination of route information and environmental information, even though this information did not always result in their optimal wayfinding performance.
Independent wayfinding is a significant and impeding problem for most people who are visually impaired (that is, those who are blind or have low vision) (Marston & Golledge, 2003). During the past two decades, there has been an increase in research on and the development of electronic travel aids to assist people who are visually impaired with navigation. These aids provide either tactile or auditory feedback about an individual's surroundings and information about the route to be followed (for an overview of existing systems, see Roentgen, Gelderblom, Soede, & de Witte, 2008). To develop electronic travel aids into user-friendly assistive devices, it is essential to discover which information people who are visually impaired require to find their way successfully. The focus of the study presented here was on the effectiveness of different types of verbal information that is delivered by electronic travel aids for navigation.
An electronic navigation system can provide information about a route and about the individual's surroundings (hereafter "environmental information"). Route information contains directional information that the user needs to find his or her destination. Environmental information includes references to landmarks in the environment. Landmarks are salient environmental features that can act as anchor points for organizing spatial information in a wayfinding context for all persons, both visually impaired and sighted (Denis, Michon, & Tom, 2007; Golledge, 1999). Environmental information can "help the traveler keep oriented and develop better mental representations of the environment over multiple trips through it" (Loomis, Golledge, Klatzky, & Marston, 2007, p. 188).
It has been shown that safety and independence while traveling can be improved when the names of landmarks and information about the current location (which is mainly environmental information) are provided to persons who are visually impaired (Crandall, Brabyn, Bentzen, & Myers, 1999; Marston, 2002). Gaunet and Briffault (2005, 2008) defined several guidance functions to assist individuals who are visually impaired verbally as they navigated through urban areas. The verbal guidance could be classified as either route information or environmental information. When these guidance concepts were tested by participants who were blind in a real-life setting (Gannet, 2006), part of the environmental information, concerning the current location and orientation of the participants, was provided at the beginning of the routes and then delivered en route on the participants' demand. The results showed that the participants did not often request this information. Other environmental information (the announcements and descriptions of crossings), which were provided en route, turned out to be too wordy and might have overloaded the wayfinding process. The authors suggested that users be trained and stimulated to use the environmental information (Gaunet, 2006).
Steyvers, Van der Woude, and Kooijman (2005) compared the wayfinding efficiency of persons with visual impairments who were given route information to a pre-entered destination in a navigation device either with or without additional environmental information. The additional environmental information was found to not provide the expected advantages to efficient wayfinding. Steyvers et al. explained this finding by suggesting that the additional information may have led to an information overload. The authors predicted that extended use of the two functions (route and environmental information) would reveal an advantage. …