Supporting Visually Impaired Users


May 7, 2012 @ 14:30, Room: 18CD

Chair: Vicki Hanson, University of Dundee, UK
CrossingGuard: Exploring Information Content in Navigation Aids for the Visually Impaired - Paper
Community: user experience
Contribution & Benefit: User study to investigate the information needs of visually impaired pedestrians at intersections. We also present a system to gather the necessary information using Google's Street View and Amazon's Mechanical Turk.
Abstract » Visually impaired pedestrians experience unique challenges when navigating an urban environment because many cues about orientation and traffic patterns are difficult to ascertain without the use of vision. Technological aids such as customized GPS navigation tools offer the chance to augment visually impaired pedestrians� sensory information with a richer depiction of an environment, but care must be taken to balance the need for more information with other demands on the senses. In this paper, we focus on the information needs of visually impaired pedestrians at intersections, which present a specific cause of stress when navigating in unfamiliar locations. We present a navigation application prototype called CrossingGuard that provides rich information to a user such as details about intersection geometry that are not available to visually impaired pedestrians today. A user study comparing content-rich information to a baseline condition shows that content-rich information raises the level of comfort that visually impaired pedestrians feel at unfamiliar intersections. In addition, we discuss the categories of information that are most useful. Finally, we introduce a micro-task approach to gather intersection data via Street View annotations that achieves 85.5% accuracy over the 9 categories of information used by CrossingGuard.
SpaceSense: Representing Geographical Information to Visually Impaired People Using Spatial Tactile Feedback - Paper
Community: designCommunity: user experience
Contribution & Benefit: Investigates a mobile interface that helps people with visual impairments learn directions to a location and its spatial relationships with other locations on a map through spatial tactile feedback.
Abstract » Learning an environment can be challenging for people with visual impairments. Braille maps allow their users to understand the spatial relationship between a set of places. However, physical Braille maps are often costly, may not always cover an area of interest with sufficient detail, and might not present up-to-date information. We built a handheld system for representing geographical information called SpaceSense, which includes custom spatial tactile feedback hardware�multiple vibration motors attached to different locations on a mobile touch-screen device. It offers high-level information about the distance and direction towards a destination and bookmarked places through vibrotactile feedback to help the user maintain the spatial relationships between these points. SpaceSense also adapts a summarization technique for online user reviews of public and commercial venues. Our user study shows that participants could build and maintain the spatial relationships between places on a map more accurately with SpaceSense compared to a system without spatial tactile feedback. They pointed specifically to having spatial tactile feedback as the contributing factor in successfully building and maintaining their mental map.
The User as a Sensor: Navigating Users with Visual Impairments in Indoor Spaces using Tactile Landmarks - Paper
Community: design
Contribution & Benefit: Describes an indoor navigation system that appropriates the user to be a sensor. The system can improve mobility for users with visual impairments and can be installed at low cost.
Abstract » Indoor navigation systems for users who are visually impaired typically rely upon expensive physical augmentation of the environment or expensive sensing equipment; consequently few systems have been implemented. We present an indoor navigation system called Navatar that allows for localization and navigation by exploiting the physical characteristics of indoor environments, taking advantage of the unique sensing abilities of users with visual impairments, and minimalistic sensing achievable with low cost accelerometers available in smartphones. Particle filters are used to estimate the user's location based on the accelerometer data as well as the user confirming the presence of anticipated tactile landmarks along the provided path. Navatar has a high possibility of large-scale deployment, as it only requires an annotated virtual representation of an indoor environment. A user study with six blind users determines the accuracy of the approach, collects qualitative experiences and identifies areas for improvement.
Guidelines are Only Half of the Story: Accessibility Problems Encountered by Blind Users on the Web - Paper
Community: design
Contribution & Benefit: An empirical study of 1383 problems encountered on 16 websites by 32 blind users. These problems were analysed for whether they were covered by the Web Content Accessibility Guidelines version 2.0
Abstract » This paper describes an empirical study of the problems encountered by 32 blind users on the Web. Task-based user evaluations were undertaken on 16 websites, yielding 1383 instances of user problems. The results showed that only 50.4% of the problems encountered by users were covered by Success Criteria in the Web Content Accessibility Guidelines 2.0 (WCAG 2.0). For user problems that were covered by WCAG 2.0, 16.7% of websites implemented techniques recommended in WCAG 2.0 but the techniques did not solve the problems. These results show that few developers are implementing the current version of WCAG, and even when the guidelines are implemented on websites there is little indication that people with disabilities will encounter fewer problems. The paper closes by discussing the implications of this study for future research and practice. In particular, it discusses the need to move away from a problem-based approach towards a design principle approach for web accessibility.