Use of an Indoor Navigation System by Sighted and Blind Travelers: Performance Similarities across Visual Status and Age (original) (raw)

2020, ACM Transactions on Accessible Computing (TACCESS)

This article first reviews the pros and cons of current accessible indoor navigation systems and then describes a study using commercial smart devices to navigate routes through a complex building. Our interest was in comparing performance when using real-time narrative descriptions (system-aided condition) vs. a memory-based condition where the same narrative information was only provided to users from the route's origin. We tested two groups of blind and visually impaired (BVI) users, including people above and below 60 years of age, as well as a third sighted control group. Evaluating older BVI participants is important, as the majority of vision loss is age-related, yet navigation performance using access technology is rarely studied with this demographic. Behavioral results demonstrated that access to real-time (system-aided) information led to better navigation accuracy and greater confidence by blind users compared to the information-matched memory condition. Performance for blind participants over 60 years old was nearly identical with their younger peers-an important outcome supporting the efficacy of using navigational technologies by this fast-growing population. Route completion accuracy and requests for assistance did not reliably differ between blind and sighted participants when using the system, suggesting that access to narrative route information led to functionally equivalent navigation behavior, irrespective of visual status. Survey results revealed strong user support for real-time information and provided important guidance for future interface refinements. 1 INTRODUCTION The reason that indoor navigation is often more challenging than traveling outdoors is partly due to technical limitations, as GPS-based positioning is unreliable within large buildings [ 1 ]. Although various technologies have been tested for supporting indoor localization (see Reference [ 2 ] for review), none have yet emerged as a widespread and widely used standard analogous to GPS-based outdoor navigation. Beyond technical limitations, the indoor navigation challenge is exacerbated by the nature of indoor spaces, as buildings are usually multi-level 3D structures with limited naming conventions for the walkable regions or addressing schemes of specific locations, i.e., the street names and building addresses that support outdoor travel [ 3 ]. As a consequence, it is more difficult to accurately represent the building structure on a real-time navigation map or to provide turn-by-turn verbal route instructions, as is available with outdoor navigation systems. These differences frequently make indoor navigation, especially when finding routes through large buildings, more frustrating and error-prone [ 4-6 ]. To help mitigate these indoor navigation challenges, architects and building developers utilize a host of aids to assist indoor wayfinding, such as maps, signs, directional arrows, alphanumeric room labels, and color-coded cues for distinguishing different spatial regions. Most of these tools for self-orientation and localization are visual in nature. As a result, anybody navigating in large, complex buildings is at a particular disadvantage if they cannot visually access this key wayfinding information, as is the case for blind or visually impaired (BVI) travelers or in situations when vision is not available (e.g., the power goes out, emergency response scenarios, etc.). This is a well-known problem and the quest for a viable solution has motivated an active research community studying technological approaches to support nonvisual indoor navigation, primarily for use by BVI travelers. Rather than focusing on technical development, our emphasis here was on investigating how use of the navigation system impacted behavioral performance. Several human factors and user interface (UI) parameters were addressed in the study, including: perception vs. memory-based information access, participant age, visual status, and collaborative navigation techniques. Results from route navigation performance (quantitative evaluation) and system usability evaluations (qualitative feedback) demonstrated that people perform best when they have access to real-time (perceptual) guidance from a navigation system and that this benefit is similarly manifested for both older and younger BVI participants and between sighted and blind users. In the remainder of this article, we (1) provide a background of accessible indoor navigation systems, (2) give an overview of the system we used to support the study, (3) discuss the relevance of our variables of interest with respect to probing how (and for whom) accessible navigation systems are generally used, (4) describe an in situ study carried out in a large university building using our system, and (5) couch the findings in terms of how they relate to existing research with navigation systems and