James R. Marston

Measuring Accessibility for People with a Disability

This paper discusses some of the inherent problems associated with measuring accessibility for people on a landscape of surfaces, barriers, and travel modes. Along with this discussion we propose a new perspective for measuring accessibility with a focus on people with differing abilities. Even though our focus is on people with a physical disability, such an approach can be easily extended and is able to be generalized to other needs and differences. Traditional measurements of accessibility are flawed, as they fail to directly account for mobility and physical differences among people. They ignore structural barriers and individual mobility limitations that affect travel time, effort, and even successful completion. To make sense of this dilemma, we propose an accessibility measurement framework that includes measures of absolute access, gross access, closest assignment access, single and multiple activity access, probabilistic choice access, and relative access. Most of these measures of access have been proposed by others, but our framework attempts to codify an approach that helps to overcome weaknesses in using only the absolute access measurement currently used in ADA compliance. Such measures can be used to map accessibility as well as to help select the mitigation or renovation projects that yield the greatest increase in accessibility for people with disabilities. We argue that for many urban and building design problems providing absolute access for people with physical disabilities should be accompanied by the use of a relative access measurement, so that removing barriers can be done in the order that provides the greatest improvement in access for a given level of expenditure.

INVESTIGATING TRAVEL BEHAVIOR OF NONDRIVING BLIND AND VISION IMPAIRED PEOPLE: THE ROLE OF PUBLIC TRANSIT

Our purpose is to explore the travel behavior of blind or vision impaired people, focusing in particular on travel by bus. We differentiate the sample depending on the availability of a household car. We examine perceptions of and attitudes toward existing transit and various transit characteristics, highlighting features that seem to be frustrating or difficult. Finally, we have travelers evaluate the potential usefulness of various assistive devices, including electronic information that gives navigational assistance.

A relative access measure to identify barriers to efficient transit use by persons with visual impairments.

Purpose. Persons with visual impairments or blindness can face significant restrictions to their efficient travel, especially when attempting transit transfers and using a large, multi-modal terminal. Little is known about what makes some tasks much harder than others. This paper presents an approach to empirically measure the difficulty of a variety of transit tasks. Method. An experiment was conducted at an urban transit terminal, with three other transit modes nearby. Thirty persons with visual impairments attempted to make five simulated transfers between these modes. Errors and time to complete these tasks were collected in order to quantify the nature of various barriers to efficient travel for this group. In total, 20 locations were visited. Completion times were compared to a sighted traveler to determine a measure of the time penalty, or ‘relative access measure.’ Results. Two basic findings are reported. Empirical data showed that different types of transit tasks and locations had a wide range of difficulty and inherent time penalties. Some tasks like crossing a difficult street, finding unmarked track doors, and finding inconsistently placed amenities were quite time consuming and sometimes impossible to accomplish. Other tasks, like walking to a street corner and crossing a simpler street, had much lower penalties and could be completed with ease. Conclusions. The placement of additional cues, those of identity and direction, provided with auditory signage, were able to eliminate much of the uncertainty and time restrictions associates with transit use and navigation for persons with visual impairments.

An n-back task using vibrotactile stimulation with comparison to an auditory analogue

We report a vibrotactile version of the common n-back task used to study working memory. Subjects wore vibrotactile stimulators on three fingers of one hand, and they responded by pressing a button with the other hand whenever the current finger matched the one stimulated n items back. Experiment 1 showed a steep decline in performance as n increased from 1 to 3; each additional level of n decreased performance by 1.5 d′ units on average. Experiment 2 supported a central capacity locus for the vibrotactile task by showing that it correlated strongly with an auditory analogue; both tasks were also related to standard digit span. The vibrotactile version of n-back may be particularly useful in dual-task contexts. It allows the assessment of cognitive capacity in sensory-impaired populations in which touch remains intact, and it may find use in brain-imaging studies in which vibrotactile stimuli impose a memory load.

Helping Hands versus ERSP Vision: Comparing Object Recognition Technologies for the Visually Impaired

A major challenge for people with vision impairments ranging from severely low visual acuity to no light perception (NLP) is identifying or distinguishing the difference between objects of similar size and shape. For many of these individuals, locating and identifying specific objects can be an arduous task. This paper explores the design and evaluation of the “Helping Hand”: A radio frequency identification (RFID) glove that audibly identifies tagged objects. In this paper we describe the design of a wearable RFID apparatus used for object identification. We evaluated the effectiveness of the glove by conducting a three-arm randomized controlled study. In our experiment, we compare a baseline (no assistive device), RFID (Helping Hand) and computer vision (ERSP Vision Software) in identifying common household objects. We also administered a questionnaire to obtain subjective data about the usability experience of the participants. Our experimental results show a reduction in the amount of time required to identify objects when using the Helping Hand glove versus the other two methods.

Spatial knowledge acquisition: using technology, training, and techniques to enhance spatial learning for two special populations

Visual cues are a very helpful means of learning an environment easily and quickly. People who are blind cannot access many of the cues that guide most people. Likewise, those with developmental disabilities can often not understand signs and cues in the environment. This talk will look at several studies that have pointed out technologies, training, and techniques that can assist these two groups to better understand spatial information and lead to better spatial decision making and cognitive maps. People who are blind or visually impaired exhibit a wide range of spatial abilities, just like their sighted counterparts. The literature shows an equally wide range of theories on the ability of this group to accurately acquire spatial knowledge and the ability to construct valid and useful cognitive maps. Spatial information is especially important when dealing with novel environments. This presentation first reports on an experiment that used auditory cues (Talking Signs® Remote Infrared Audible Signage [RIAS]) to increase environmental awareness in a multi-modal urban transit station. One group of participants used their regular methods of orientation and travel while the others used the additional auditory cues. Two types of tests were conducted to measure spatial knowledge acquisition. Participants were given two opportunities to make a shortcut, if they were aware of its presence. In both instances, those that used the auditory cues were vastly superior in their ability to make distance-saving shortcuts. In addition, a set of spatial relationship questions was examined. Those that used the auditory cues answered these questions much more accurately than those that used their regular methods. Participants’ times to complete various search and travel tasks, the number of errors made, and the number of requests for help from others were all superior when using the auditory cues. These additional auditory cues gave information that is not normally available and it appears that poor spatial awareness (a major problem of blind navigation) is the lack of accessible cues in various environments, not an inherent cognitive processing flaw of these individuals. Examples from work by other researchers will be discussed in the presentation. We summarize a study that tested RIAS in a subway station with a group of people who had developmental disabilities. They better understood the auditory signage information then when they tried to read that information. We also give examples from studies that tested various techniques to help blind people learn an environment, such as making sure that all cues at decision points were salient to the user, making a verbal report, constructing a model, and pointing at various visited objects. Two studies showed that when blind people were trained in these techniques, they preformed much better than without this training, and in one study, blind people were able to learn a complicated route almost as well as a sighted control group.