外文文献技术支持的导航辅助工具的要求和偏好

Hearing the way Requirements and preferences for technology supported navigation aids Laura Lewis a Sarah Sharplesa Ed Chandlerb John Worsfoldc aHuman Factors Research Group Department of Mechanical Materials and Manufacturing Engineering Faculty of Engineering University of Nottingham University Park Nottingham NG7 2RD UK bUser Vision 55 North Castle Street Edinburgh EH2 3QA UK cRoyal National Institute of Blind People RNIB Orton Southgate Peterborough PE2 6XU UK a r t i c l ei n f o Article history Received 25 June 2012 Accepted 12 November 2014 Available online 4 December 2014 Keywords Blind and partially sighted Wayfi nding Navigation a b s t r a c t Many systems have been developed to assist wayfi nding for people with sight problems There is a need for user requirements for such systems to be defi ned This paper presents a study which aimed to determine such user requirements An experiment was also conducted to establish the best way of guiding users between locations The focus group results indicated that users require systems to provide them with information about their surroundings to guide them along their route and to provide progress information They also showed that users with sight conditions interact with systems differently to sighted users thereby highlighting the importance of designing systems for the needs of these users Results of the experiment found that the preferred method of guiding users was a notifi cation when they were both on and off track However performance was best when only provided with the off track notifi cation implying that this cue is particularly important Technology has the potential to support navigation for people with sight problems Users should have control over cues provided and for these cues should supplement environmental cues rather than replacing them 2015 Published by Elsevier Ltd 1 Introduction Blind and partially sighted people face diffi culty in both navi gating through environments and knowing what is in their envi ronment This can lead to reductions in their mobility increased danger and decreased independence Walker and Lindsay 2006 Previous work has suggested that blind and partiallysighted people heavily rely on help from other people in unfamiliar places and face particular challenges in navigation in noisy environments Saenz and Sanchez 1990 This suggests that orientation may be aided through the provision of directions along the person s route In addition there are instances where sighted people may be unable to use vision to aid navigation due to carrying out other tasks which require sight simultaneously Walker and Lindsay 2006 Location based handheld technologies provide an opportunity tousetechnologytosupportnavigationusingnon visual presentations This may therefore support blind partially sighted and sighted users This paper presents a study that developed some prototype methods to support blind and partially sighted users in a navigation task The methods were derived using a user re quirements exercise that considered technology capabilities and limitations user preferences and needs and views of experts The methods were then compared in an experiment that simulated the navigation task of moving from one checkpoint tothe next for blind and partially sighted users On the basis of the fi ndings of this research the way in which different user needs were met was considered along with any improvements to the prototypes methods and identifi cation of areas for future research 2 Literature review 2 1 Characteristics of blind and partially sighted people The population of blind and partially sighted people is on one level a seemingly homogeneous group in that they all to some degree cannot access information in the same way that the rest of the population do However the underlying story is quite different Generally speaking no two people with the same eye condition Corresponding author Tel 44 0 115 748 4073 E mail addresses laura lewis nottingham ac uk L Lewis sarah sharples nottingham ac uk S Sharples ed uservision co uk E Chandler john worsfold rnib org uk J Worsfold Contents lists available at ScienceDirect Applied Ergonomics journal homepage http dx doi org 10 1016 j apergo 2014 11 004 0003 6870 2015 Published by Elsevier Ltd Applied Ergonomics 48 2015 56e69 have the same sight level and characteristics This makes the population of blind and partially sighted people heterogeneous and therefore can be diffi cult to cater for user needs on an individual istic level Bradley and Dunlop 2004 highlighted that blind and partially sighted fall into three main groups total vision loss cen tral vision loss and peripheral vision loss Within these categories are many sight conditions including glaucoma retinitis pigmentosa and macular degeneration RNIB 2013a Individuals suffering from a loss of central vision need to move their head to one side in order to see in their periphery They also need additional support when reading and performing tasks Unless treated the area of central vision loss will increase until the individual cannot see anything RNIB 2013b People who have a loss of peripheral vision need to move their heads more in order to fi nd things RNIB 2013c Once individual sight conditions are categorised more broadly into people with low vision encompassing blind and partially sighted people but have some useful vision and people with no vision encompassing blind people who have no useful vision e g can only see light or dark or nothing solutions that would benefi t the users of these two groups become more homogenous For instance when considering textual information those with low vision will generally speaking benefi t from clear visual informa tion e g large typeface and clear fonts RNIB 2009 People with no vision need to access the same information in an alternative format e g Braille other tactile information or audio RNIB 2012a The same may be true of technology supported naviga tion systems 2 2 Supporting navigation for visually impaired users Sighted people use their vision when navigating and this has been suggested to support the development of mental maps Lahav and Mioduser 2004 When visual information is not available other senses such as hearing and touch must be used However the mapping between a communication using hearing and touch does not always have such an accurate or detailed direct mapping between the user and the environment Therefore there is a need for research to understand and propose appropriate methods of using non visual media to communicate spatial information Strothotte et al 1995 found that users have a need for infor mation regarding landmarks topographical information the user s current location roadworks street names and directions Previous work has suggested that in particular it may be diffi cult to articu late descriptions of some environments for example irregularly shaped buildings and curving paths Golledge et al 1996 In addition words used to describe spatial confi gurations such as near around or the red building may be ambiguous or inap propriate for use when describing environments to blind or partially sighted individuals Golledge 1993 An alternative approach of using the clock system Sanchez 2009 has been proposed and is consistent with the theory that people with sight problems generally understand spatial confi gurations with respect to their own bodies Millar 1994 Tactile maps provide users with information regarding the relative locations of objects in space Ungar 2000 Maps that provide audio clues to location e g sounds appropriate to the environment such as the sound of traffi c or people have also been proposed to support understanding of spatial confi gurations These have been demonstrated to support the formation of mental maps for blind and partially sighted users Jacobson 1998 The opportunities presented by new technologies to support navigation have also been investigated The System for Wearable Audio Navigation SWAN made use of non verbal audio to portray information It was found that the use of beeps was less distracting than speech and also easier to distinguish from environmental sounds Discovery Channel Canada 2007 This method used the concept of waypoints to guide users with beeps increasing in frequency as they were approached Goulding 2010 also used the concept of waypoints in a visually based system that used a mobile device torepresent arches along a route Walkerand Lindsay 2006 proposed the use of a capture radius around waypoints to ensure that users were able to detect them when they were nearby The Personal Guidance System PGS has also been used totest a number of ways of portraying information to blind and partially sighted users using spatial displays One study compared the use of non verbal audio synthesised speech and or vibrations which were initiated either from the position of the hand or the torso It was found that participants were able to complete the tasks faster with auditory cues and generally liked spoken information about the distance to the next waypoint Loomis et al 2005 Ertan et al 1998 also developed a system of navigation which made use of a haptic directional display which was integrated into a wearable vest Beacon based technologies such as ORTI Kemmerling and Schliepkorte 1998 and RNIB REACT RNIB 2012b have also been developed These provide information tousers about theirlocations via units which are situated in fi xed places Whist these systems can provide users with context specifi c information the usefulness of such systems has been questioned due tothe need for users to be aware of the existence and location of these beacons Worsfold and Chandler 2010 GPS technologies which can support navigation for blind or partially sighted people are also commercially available These include the Trekker Breeze and the Kapten Plus The Kapten Plus is voice activated and provides spoken turn by turn navigation RNIB 2012c The Trekker Breeze uses speech to provide information about the user s surroundings including road names junctions and points of interest It also allows users to record routes and land marksandwillprovidestep by stepjourneyinstructions Humanware 2012 Drishti a research based system took this one step further by optimising routes based on real time information It was designed to select routes based on user preferences as well as dynamic events and obstacles for example roadworks or high volumes of traffi c It also warned users of hazards in their locale Helal et al 2001 Strothotte et al 1995 found that users have a preference for information to be provided using synthetic speech rather than non verbal audio or vibratory cues Conversely Holland et al 2002 found that users were able to use non verbal sounds to portray information regarding the direction distance and location of landmarks with respect to the user Their system used direc tional audio and trials indicated that users were able to discern the direction of sounds However the authors did note the challenges presented by multiple auditory cues that could quite quickly lead to a cluttered audio output Spatial sound has also been suggested to be useful in allowing users to differentiate between multiple sounds being played simultaneously as well as in series Brewster et al 1995 Tran et al 2000 suggested that in order for the perceived location of a sound to match the target location in the real world it should be easy to localise and follow different enough from environmental sounds easy to hear over other noises and should not distract or frustrate the user Although users have been found to more accurately locate directional sound when it is of a higher frequency and relative wide band people tend to prefer lower frequency sounds as they are deemed to be less annoying Tran et al 2000 This demonstrates that it is important to consider both user preference and performance in developing and evaluating any navigational cues Earcons which are abstract sounds that can be used to represent parts of in terfaces have been demonstrated to be particularly effective at L Lewis et al Applied Ergonomics 48 2015 56e6957 grabbing users attention through changing the rhythm or pitch of a sound or by changing its tempo Brewster et al 1995 and so may be useful when providing cues which alert users to hazards and obstructions The work presented in this paper consists of two studies For the fi rst study a series of focus groups was conducted to develop an understanding of the way in which blind and partially sighted travellers currently complete their journeys and to elicit user re quirementsfortechnology supportednavigationaids This informed both the design of the navigationprototype cues and also the task conducted within the experimental phase of the work These requirements were then validated by technology experts who provided insight into current and future capabilities of mobile technologies and experts from the Royal National Institute for the Blind RNIB who contributed specifi c knowledge of the way in which visually impaired and blind users complete journeys In the second study a smallsetof prototype navigation aids weretested in a constrained experimental scenario with blind and visually impaired users Therefore the aims of the studies were Study 1 to elicit user requirements for mobile location based technologies to support navigation for blind and partially sighted users and Study 2 to evaluate some prototype tools that emerged from these requirements in a structured experimental setting 3 Study 1 requirements elicitation 3 1 Focus groups 3 1 1 Focus group method Three categories of users participated in focus groups people who were born with sight loss people who have developed a sight problem and sighted people Twenty three people participated in the focus groups and each focus group comprised between three and six people All participants were either RNIB employees or were recruited through a database of RNIB volunteers Eleven participants were born with sight loss nine developed a sight problem and three were sighted None of the participants had any other disabilities All participants were independent travellers and all participants with sight conditions made use of eithera guide dog or a cane Although fi gures were not collected it is estimated from anecdotal evidence that approximately 75 of all participants with sight conditions had experience using devices such as a Trekker Breeze or Kapten Plus The participants were all aged between 26 and 82 with a mean age of 49 1 and a standard deviation of 16 51 Participants were asked to rate their experience using technology on a fi ve point scale where one was no experience and fi ve was very experienced The median rating was 4 with an inter quartile range of 1 The participants were divided into four focus groups comprising between three and six people One of these groups was made up of sighted people The remaining groups weremade up of a mixtureof participants with regard to severity of sight condition and whether they were born with or had developed these conditions For all participants who were not sighted research materials including participant information sheets consent forms and questionnaires were offered in alternative formats e g audio or Braille The focus groups were semi structured and aimed to elicit understandingof the nature of cues that could be used frequencies as well as the way in which visually impaired people currently plan and navigate journeys Sample audio cues were provided as described in Table 1 It should be noted that the sounds provided were intended to prompt debate and to determine generic preferences for sounds rather than being examples of exact sounds to be used in a future wayfi nding technology A pilot study was conducted with fi ve people with sight conditions to refi ne ques tions and session format The focus groupswerevideo recorded and the facilitator also made written notes during the sessions 3 1 2 Focus group results Data from the focus group was analysed using theme based content analysis Neale and Nichols 2001 The comments of the participants are described below and the requirements summar ised in tables at the end of this section It should be noted that no differences were found in terms of the categories of participants with sight conditions i e severity of condition and whether the conditionwas present from birth or had developed Therefore distinctions are only made between sighted participants and those with sight conditions Unless otherwise stated the term participants refers to those who were blind or partially sighted 3 1 2 1 How people currently carry out journeys The participants had avariety of methods of eliciting information in order to plan for journeys before carrying them out The most common methods amongst the blind and partially sighted participants were speaking to people and using technology such as websites to plan routes One participant stated that they would familiarise yourself as much as you can using tools like the internet and word of mouth phoning up e Participant 20 Another common method was to practise the route with a sighted person before going alone If I were going to unfamiliar places I have a test run fi rst so as I ve got things to pick out e Participant 1 This comment also emphasises the use of waypoints or land marks i e things to pick out In contrast to these methods the sighted participants tended to use maps to plan journeys The most common method of obtaining information when carrying out journeys for the blind and partially sighted partici pants was to ask people This included members of the public and public transport staff as well as using station escorts to take them from the train to their destination The use of technology including GPS and announcements onpublic transport were also used Some participants made use of environmental cues such as sounds and noting the trajectory of the ground I can hear the