MOBILE INTERACTION: AN ANDROID-BASED PROTOTYPE TO EVALUATE HOW WELL BLIND USERS CANINTERACT WITH A TOUCH-SCREEN  First Aut...
The paper is organized as follows: after a brief introduction    possible without sight, including making phone calls, tex...
was mainly based on gestures like left/right and up/downflicks, taps and double taps. For instance to go through themenus ...
•    Double vibration for the odd numbers except for                            Figure 2 Software keyboard         5(1, 3,...
and development cycle. The experimental protocol was            T5       Searching for a flight Exploring a tabledivided i...
In Table 1 the average (M) and the standard deviation (SD)      achieved the best results. This implies that the accessibi...
gave their view on their usefulness. The average value             replaced by "Send" when writing an SMS message, orobtai...
This kind of feature located in fixed places can        ACKNOWLEDGMENTS         improve user interaction.                 ...
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SMARCOS_Paper_Mobile hci12 246

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Mobile devices are increasingly becoming part of everyday
life for many different uses. These devices are mainly based
on using touch-screens, which is challenging for people
with disabilities. For visually-impaired people interacting
with touch-screens can be very complex because of the lack
of hardware keys or tactile references. Thus it is necessary
to investigate how to design applications, accessibility
supports (e.g. screen readers) and operating systems for
mobile accessibility. Our aim is to investigate interaction
modality so that even those who have sight problems can
successfully interact with touch-screens. A crucial issue
concerns the lack of HW buttons on the numpad. Herein
we propose a possible solution to overcome this factor. In
this work we present the results of evaluating a prototype
developed for the Android platform used on mobile
devices. 20 blind users were involved in the study. The
results have shown a positive response especially with
regard to users who had never interacted with touchscreens

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SMARCOS_Paper_Mobile hci12 246

  1. 1. MOBILE INTERACTION: AN ANDROID-BASED PROTOTYPE TO EVALUATE HOW WELL BLIND USERS CANINTERACT WITH A TOUCH-SCREEN First Author Name (Blank if Blind Review) Second Author Name (Blank if Blind Review) Affiliation (Blank if Blind Review) Affiliation (Blank if Blind Review) Address (Blank if Blind Review) Address (Blank if Blind Review) e-mail address (Blank if Blind Review) e-mail address (Blank if Blind Review) Optional phone number (Blank if Blind Review) Optional phone number (Blank if Blind Review)ABSTRACT the interaction with smartphones more difficult andMobile devices are increasingly becoming part of everyday complex for those who are blind. Interaction modalitieslife for many different uses. These devices are mainly based based on gestures and taps can be a practicable solution,on using touch-screens, which is challenging for people provided they are well designed and simple to use. Applewith disabilities. For visually-impaired people interacting has already put on the market devices accessible to userswith touch-screens can be very complex because of the lack with disabilities, such as iPhone 3G, 4 and 4Sof hardware keys or tactile references. Thus it is necessary (http://www.apple.com/accessibility/). At the same timeto investigate how to design applications, accessibility there are also some active projects aimed at studying how tosupports (e.g. screen readers) and operating systems for provide access to devices based on the Android systemmobile accessibility. Our aim is to investigate interaction (http://eyes-modality so that even those who have sight problems can free.googlecode.com/svn/trunk/documentation/android_accsuccessfully interact with touch-screens. A crucial issue ess/index.html). However, all these solutions and studiesconcerns the lack of HW buttons on the numpad. Herein are still at the early stages. It is therefore important towe propose a possible solution to overcome this factor. In understand the suitability of the new interaction modalitiesthis work we present the results of evaluating a prototype with touch-screen devices for people with visiondeveloped for the Android platform used on mobile impairment. Our aim is to evaluate if there are still aspectsdevices. 20 blind users were involved in the study. The to be made more accessible and usable for user interaction.results have shown a positive response especially with In [Errore. Lorigine riferimento non è stata trovata.]regard to users who had never interacted with touch- the authors observed some usability issues encountered byscreens. blind users while interacting with the tablet iPad, although the VoiceOver support seems to be generally accessible.Author Keywords This implies that there are still mobile accessibility issues toMobile accessibility, mobile interfaces, blind users be analyzed and evaluated in order to enhance blind user interaction with a touch-screen.ACM Classification KeywordsH.5.2 [Information Interfaces and Presentation]: User The study presented in this paper is part of mobileInterfaces – Input devices and strategies, Voice I/O, Haptic accessibility research with particular reference to theI/O. K.4.2. [Computers and society]: Social issues – interaction with touch-screen based smartphones for blindassistive technologies for persons with disabilities. people, especially for a first-time user. Devices based on the Android platform are still not particularly accessible andGeneral Terms usable by blind people. So we have selected this particularDesign, Experimentation, Human Factors. platform to investigate mobile interaction by blind users. The aim is to gather information, suggestions andINTRODUCTION indications on interaction with a touch-screen by blind usersNowadays mobile devices are used more and more for a which should be considered when designing mobilevariety of purposes. This is due to the increasingly applications and support as well. To this end, in this workadvanced features offered by the smartphones, which can we present a prototype application designed to make theprovide additional functionalities compared to traditional main phone features available in a way which is accessiblephones. The interaction modality which is increasingly used for a blind user. The prototype has been developed to firstlyfor these devices is mainly via a touch-screen display. The evaluate the interaction modalities based on gestures, audioabsence of hardware keys and any tactile reference makes and vibro-tactile feedback. A small group of blind people was involved at an early stage of the prototype developmentPermission to make digital or hard copies of all or part of this work for to collect first impressions and preferences which werepersonal or classroom use is granted without fee provided that copies are considered during the design phase of the study.not made or distributed for profit or commercial advantage and that copies Subsequently a structured user test was conducted to collectbear this notice and the full citation on the first page. To copy otherwise,or republish, to post on servers or to redistribute to lists, requires prior qualitative and quantitative data from the blind users’ pointspecific permission and/or a fee. of view.MobileHCI 2011, Aug 30–Sept 2, 2011, Stockholm, Sweden.Copyright 2011 ACM 978-1-4503-0541-9/11/08-09....$10.00.
  2. 2. The paper is organized as follows: after a brief introduction possible without sight, including making phone calls, textto existing mobile studies, we describe the application messaging, emailing and web browsingprototype developed to investigate interaction modality (http://www.google.com/accessibility/products/). [10]with a touch-based display. Next we report on the user test describes an example application developed for the blindconducted to evaluate the prototype. Conclusions end the using an Android-platform device. However, the proposedwork. work on accessibility support is still in progress and input/output modalities need to be investigated in order toRELATED WORK identify the most appropriate modalities used to interactSeveral works have been recently proposed in literature to with a touch-screen.research mobile interaction by people with disabilities.With reference to visually-impaired users some studies PROTOTYPE DESIGNdiscuss the “importance” of touch when interacting with a The proposed prototype is an application for the Androidmobile device [1, 6]. Further studies are related to the way system for mobile devices. It was tested on Samsungto combine and exploit various interaction modalities and Galaxy S, Samsung Nexus S and Huawei IDEOS. Thetechniques in order to enhance blind user interaction. In application is not in any way intended to replace screenfact, a multimodal approach can be a valuable way to reading software. Instead it is designed to implement thosesupport various interaction modes, such as speech, gesture features and functionalities that could be used to assess andand handwriting for input and spoken prompts. The tests understand the most appropriate user interaction via adescribed in [2] showed that user performance significantly touch-screen. So, for the prototype we implemented theimproves when haptic stimuli are provided in order to alert basic phone functionalities (contacts, call, read/write anusers to unintentional operations (e.g. double clicks or slips SMS (text message) and read information in table format).during text insertion). However, the study mainly focuses We also implemented the user setting functionality in orderon the advantages of exploiting the haptic channel as a to allow the user to choose how to provide and receivecomplement to the visual one and is not concerned with information using the phone (e.g. editing modality, type ofsolutions for blind users. By combining various interaction vibration, etc.). This was also useful to switch from onemodalities, it is possible to obtain an interactive interface modality to another. When designing the applicationsuitable for users with varying abilities. A well-designed prototype we considered the following aspects to bemultimodal application can be used by people with a wide evaluated for our purposes:variety of impairments. In [Errore. Lorigine riferimentonon è stata trovata.] the authors evaluated a combination • Interaction with a multimodal interface based on aof audio and vibro-tactile feedback on a museum guide, touch-screen (gestures) and feedback (audio andwhich had a positive response for the user with vision vibration);impairments. The study introduced in [8] considers the • Organization and consistency of the user interfacehaptic channel combined with audio feedback to improve (e.g., menus, buttons and labels);graphic perception by blind users. With regard to userinterface (UI) design, the work presented in [11] suggests • Editing content (e.g., SMS text or phone number).an important principle which should be considered whendesigning a product: developers should focus on ability Gesturesrather than disability. This interesting concept has been The interaction modality implemented with the prototypeconsidered in several pilot projects, including Slide Rulewhich studied touch-screen access for blind users. Inparticular, Slide Rule is a prototype utilizing accuracy-relaxed multi-touch gestures, “finger reading” and screenlayout schemes to enable blind people to use unmodifiedtouch-screens [4]. A very critical aspect for a blind personis related to input interaction. Several studies have beeninvestigating possible alternatives to propose as solution tosuch issues [9].In our work we intend to investigate if gestures and voiceand vibro-tactile feedback can be useful for the blind toconfirm an action on an Android-based smartphone. TheAndroid platform includes a built in text-to-speech engineand a screen reader so that phone manufacturers canprovide accessible smartphones. Android phones can alsobe highly customized by downloading third-party Figura 1 Menu flicksaccessibility applications that make nearly every function
  3. 3. was mainly based on gestures like left/right and up/downflicks, taps and double taps. For instance to go through themenus the user can proceed via right and left flicks. To User Interfaceconfirm a menu item a double tap is required. When designing the prototype, certain aspects concerning the organization and arrangement of the Interface such asFeedback the best structure and the most appropriate position and sizeBoth audio and vibro-tactile feedback was used to provide of the items were analysed. This was to ensureUI information. In relation to the audio feedback, we identification of the UI elements was simple and to makeconsidered: use of prior knowledge of the usual positions for keys. The main UI elements considered in the prototype can beVocal messages. all the spoken messages are created by a summarized as: Menus and sub-menus. All availablevoice synthesizer. We used a text-to-speech engine functionalities have been grouped into menus and sub-available for the Android platform menus according to macro topics.(https://market.android.com/details?id=com.svox.langpack.installer&hl=it). Set-corner buttons. In order to facilitate some main actions, four buttons were placed at the four displayShort sounds. A very short beep was used to notify the corners:beginning and end of an item list. While navigating a list ofelements using left or right flick , when the focus is over • (1 – top left) ‘exit/back’ to go to the previous step,the first or last item a short sound announces the end of thelist. For the list of elements, such as menus, SMSs, and • (2 – top right) ‘Position’ to know the currenttable cells, the focus moves in a cyclic way. Using the ‘next position status (e.g. editing numpad),gesture’ (e.g. left flick) the focus moves from the last item • (3 – bottom left) ‘Repeat’ to use for reading theto the first one, and vice-versa,, and a short sound is emitted edited content (e.g. phonenumber or content text)to notify the end of the list. in order to check if there is any error or read all theFor the vibro-tactile feedback, we exploited the vibration written message (e.g. an SMS message),functionality available on the phone for: • (4 – bottom right) ‘Done’ to be used as an ‘OK’Action confirmation. A very short vibro-tactile response button to confirm the current action.was provided when selecting a UI element (e.g. menu item Buttons (2) and (3) are particularly useful for a blind personor button) with a double tap. This feedback is in addition to so they know the current status and position at any timethe voice tone change to provide confirmation of an action. without having to explore the whole screen, as described inButton and key detection. To allow the user to quickly another study [Errore. Lorigine riferimento non è statadetect a button or a key, a short vibro-tactile response can trovata.] related to the focus issues.be perceived when touching the item. This solution wasapplied only to some buttons and keys in order to Editing Contentunderstand its benefit if compared with those just Editing via a touch-screen is a challenge for blind peopleannounced by voice. due to the lack of hardware keys. Typing both a phone number and a text becomes particularly difficult. The main issue is related to key detection in a simple and reliable way. Thus for editing activity we considered: numeric keypad (numpad), keyboard and editing modality. Numeric Keypad Detection To support the detection accessibility for the numpad some possible solutions have been considered. In the prototype the numpad keys were identified using (1) number vocalization and (2) key vibration. In a first prototype version, the vibration was used to mark only the number 5 as it is commonly used in the hardware numpad. Based on the preliminary comments received from the end users during the prototype development, the solution implemented for the user test provides different vibro- tactile feedback: • Single vibration for even numbers (2, 4, 6, 8 and Figura 2 Four buttons in the screen corners 0);
  4. 4. • Double vibration for the odd numbers except for Figure 2 Software keyboard 5(1, 3, 7 and 9); • Triple vibration for the number 5 . modality, i.e. single or double tap to confirm the touched letter (see next paragraph). Editing Modality Two editing modalities were implemented to select either a number or letter: (1) single tap and (2) double tap. Single tap means the user can explore the screen (i.e. keyboard or numpad) using a finger without leaving the screen. When the finger is hovering over the desired letter / number, by raising it (i.e. event up) the last key touched is confirmed (i.e. edited). Whereas a double tap means the user is freed to explore. . When the desired letter / number is identified, a double tap is used to select (i.e. (i.e. edit). USER TEST Overview In order to evaluate the effectiveness and efficacy of the Figure 1 Numeric keypad interaction modalities available in the prototype, a structured test with end users was conducted in order toThe different vibration frequencies have been designed to collect objective and precise information. The main goalprovide a possible support in order to better detect the was to understand if the interaction modality implementednumber being touched.. For example, the user can via gesture and vibration could be suitable for a blind user.recognize the number ‘5’ on the basis of the triple vibration. We also planned to collect information on UI design inThen by sliding the finger to the right when you feel a relation to menus, labels, buttons and audio/vibro feedback.single vibration (even numbers) it means it is the key 6 . The evaluation was targeted at answering the following questions: (1) Is the proposed gesture-based interactionInstead when you feel a double vibration (odd numbers), it appropriate for a blind person? (2) Is the arrangement of themeans that the finger has shifted slightly upwards (so it UI elements suitable for quickly detecting the interactivemust be 3) or down (9). This should support number elements? (3) How easy to learn and to use is thedetection especially in a noisy environment. application? We were particularly interested in recording perceived difficulties together with critical issues for usersKeyboard when editing modality through a single / double tap as wellFor text editing, a virtual qwerty keyboard was as comments on using the numpad and keypad. Vibro-implemented in the prototype. No vibration support was tactile feedback was also considered in our evaluation.provided. When each key is touched it is announcedvocally. In this case we focused especially on the editing Method Participants Twenty totally blind users (7 female and 13 male) were involved in the user testing. The participants were recruited in collaboration with the Association for the Blind in Italy. The age ranged from 22 to 70 years. All of the people use a computer with a screen reader in Windows an environment on a daily basis. Five of them had no experience with smartphones and touch-based screens, thirteen of them had interaveragete experience, whereas two of them had very good knowledge in using the iPhone device. Test protocol Four meetings were held at four local offices of the Italian Association for the Blind in different cities. Five users were involved for each test. At the beginning of each meeting a general presentation of the test purpose was made, highlighting the importance of the user’s role in the design
  5. 5. and development cycle. The experimental protocol was T5 Searching for a flight Exploring a tabledivided into three phases: time in a time table) (rows and columns)Preliminary phase: participants were provided with an T6 Making a call (vibro- Editing a numberoverall description of the prototype as well as with a list tactile numpad andsummarising the most important gestures and UI elements; single tap)Training phase: each user was allowed to explore theapplication for 20 minutes in order to gain confidence with As we were especially interested in comparing the editingthe smartphone and the gesture-based interaction; method using a single tap with the double tap, we assignedTesting phase: for each user an individual test session was two tasks with the same action, i.e. editing a number (T2carried out. Each of them was asked to perform a set of and T3). In order to avoid the potential bias created by thetasks and the execution time had been register by means of learning effect in using the numpad in the task 2 and 3, wethe chronometer. The users were observed while carrying balanced the users by carrying out the two tasks in aout the tasks. We applied the “thinking aloud” method to different order: T2 and T3 and vice-versa. We applied thiscollect information as the user was interacting with the modality to all the four sessions with the 20 users. T6 wasprototype. introduced to evaluate the usage of vibro-based numpad in order to understand if vibro-tactile support is a feasibleThe training phase was designed to avoid the bias of ability: solution for detecting keys more easily. However, for thiswhich means discrepancies in interaction abilities within specific solution we plan to investigate further so as tousers associated with a different degree of individual collect additional information on the possibility that thistraining, can affect the result of a test: the training phase support can improve interaction when using a numpad..allowed the participants to start the testing procedure withsimilar basic skills especially regarding knowledge of Post questionnairegestures. After performing the test, participants were asked to fill in a questionnaire composed of 22 questions. This made itThrough this test procedure both subjective and objective possible to collect information about the mobile devices anddata were gathered for each user in order to collect useful smartphones used by the participants, and to obtain otherinformation on the evaluation. With regard to objective data qualitative data not obtainable during the observations.we recorded some information for each task: (1) Time spent Subjective information was also considered. For example,by users performing assigned tasks, (2) task users could express opinions and ideas about the usefulnessaccomplishment (success/failure), (3) errors made in of audio , vibro-tactile feedback, labels, keypad andperforming the task. Regarding subjective data we collected numpad, etc. Indications about the level of difficulty ofcomments and suggestions during both the training and test editing were also taken into account. The questions regardssession by observing the users while they were using the the following topics:application. Also specific questions and interviews allowedus to collect further useful information. • General information about userTasks • Prior knowledge and experience of using mobiles,To evaluate the interaction modality developed with the and user expectations of a SmartphoneAndroid-based prototype we designed six tasks to be • Suggestions/opinions regarding multi-modalperformed by each user. The type of task was selected mobile interactionaccording to the interaction modality to be evaluated. Thesix tasks assigned to each user during the test session are • Prototype evaluationlisted in the table below.Task Description Goal For the first three topics the user has to choose the responseT1 Reading an SMS Gesture-interaction among a set of options. For the last topic the user has to message with the menus and give evaluation about specific prototype feature in a range main buttons from 1 (lower value) to 5 (higher value). For all the topics itT2 Making a call (single Editing a number was possible for the user provide comments and suggestion. tap) EVALUATION RESULTST3 Making a call (double Editing a number As said, during the test procedure objective and subjective tap) data were gathered.T4 Sending an SMS Editing a text Objective data message (qwerty keypad)
  6. 6. In Table 1 the average (M) and the standard deviation (SD) achieved the best results. This implies that the accessibilityvalues relating to the time spent by users performing of the task improves with practice.assigned tasks are provided. Time spent Task M SD Subjective data T1 01:41,4 01:01,8 T2 02:04,4 01:07,4 All users have experience of Symbian technology and they T3 01:47,1 00:45,2 use Symbian mobile phones. 55% of users had never used a smartphone and they stated that they had no knowledge of T4 01:44,4 00:43,7 touch screen technology. Moreover, the users were T5 01:25,7 01:02,3 questioned about the features they would like to have on a T6 01:54,7 00:45,0 smartphone. The result is that 85% of users are interested in Table 1 Time spent traditional phone functionalities (i.e. phoning, SMSs, contacts); 71% are interested in internet access while 69%Only successfully completed performances are taken into would like to have access to email. Few users declared theiraccount. interest in reading e-books and taking notes.In Table 2 the average success or failure rates for the task In the “Smartphone knowledge” section of theaccomplishment are provided. questionnaire, the users were asked for detailed opinions on mobile device interaction via touch-screen. Task accomplishment Task Success Failure 55% of users think that a software keyboard is a valid way T1 0,81 0,18 to provide input to the smartphone. It is worth noting that T2 0,85 0,14 83% of users with this view are those who have already used a smartphone. This factor suggests that users who are T3 0,85 0,14 initially reluctant to use a software keyboard can change T4 0,55 0,45 their mind after using it. T5 0,85 0,14 Instead, after using the software numpad to insert a number, T6 1,0 0,0 97% of the users think that it is a valid way to perform this Table 2 Task accomplishment function.The results show that most of the users are able to 77% of the users say that it would be useful to use a speechsuccessfully complete the tasks. As expected, text editing recognizer to provide some commands to the smartphonehas the largest failure rate. with the voice.In Table 3 the average number of errors per task is reported. The majority (88%) think that vibro-tactile feedback is a valuable way to obtain indication from the smartphone. Task Evaluation of errors T1 0,05 The last question in the “Smartphone knowledge” section T2 0,55 regards the possible presence of physical points of reference on the touch screen: 83% of the users consider that it would T3 0,55 be very helpful to have physical reference points. T4 0,85 T5 0,15 The questions contained in the “Prototype evaluation” T6 0,7 section of the questionnaire regard the evaluation of the tasks performed with the prototype application. A scale Table 3 Number of errors from 1 (negative) to 5 (positive) was employed when the user was asked to express a score.The errors considered relate to the number of attempts, andnot the number of successfully completed tasks. The users were asked about the usefulness of flick gestures when browsing the information. The average value obtainedIt is worth noting that more errors occurred in task T2 when is M:4,47. 17 users think that the gestures from left to rightit was performed after task T3 (70%). The users performed and from right to left are appropriate to scroll lists ofa double tap to select a number instead of a single tap, thus elements, while 3 users think that gestures from top tocopying the editing modality of task T3. bottom and from bottom to top would be more intuitive.During the test, it was observed that the users with Regarding the use of the 4 buttons at the corners of theexperience of smartphone and touch screen technologies screen when retrieving orientation information, the users
  7. 7. gave their view on their usefulness. The average value replaced by "Send" when writing an SMS message, orobtained is M:4,84. "Call" when making a call.In particular, 15 users expressed their appreciation of the Six users think that in some cases the phrases used to“Repeat” button for two reasons. They found it very useful introduce the activities are too long. They would probablyfor listening again to the last message or the text entered so be appropriate when first using the device, but that forfar. They also liked the fact that they could use it at any subsequent use it would be better to allow the user topoint during the interaction. This could well be a solution to customize the message. This fact suggests that the level ofthe problem observed by the authors in [Errore. Lorigine detail of the speech feedback might be an additionalriferimento non è stata trovata.]. configuration parameter.The average value obtained for vibration feedback is In conclusion, the global evaluation of the tested prototypeM:3,84. This data is the most subjective of those analyzed: is expressed with the average value: M:4:26.users are divided between believing that the vibration does Overall, users showed unexpectedly high interest in thenot provide any added value and those who think that it is application and were very willing to contribute theiressential when in noisy environments and for reasons of opinions and comments to the study.privacy.In particular it is interesting to note that the users in favourof vibration are the same as those who clearly perceive the A significant consequence of the study is that as many asdifference between the vibration in different keys. five of the participants said they would consider buying an Android smartphone in order to install this application.With regard to the single tap method for selecting a keywithin a keyboard or numpad the average value obtained is CONCLUSIONSM:4,44. Instead the approval rating for the double tap mode The study presented in this work is aimed at investigatingis M: 4.06. The general opinion is that the double tap is the interaction with mobile devices by users with visualbetter suited for novice users because it would result in impairments. To this end, we chose Android-poweredmore successful editing. Interestingly novice users who devices and we developed a prototype application toexpress this view claim to interact better when using the implement some targeted functionalities, which allowed ussingle tap mode. to analyse and evaluate how well the blind user is able toBoth novices and experienced users agree that the single tap interact and work with a smartphone. Although theis a faster way to insert the text in general. However, they prototype developed is limited to only a few features for thethink that using a single tap is not suitable for critical Android operating system, the results obtained from blindactions such as “Done” or “Delete”. They say they would user interaction with an Android-based device can befeel more secure with a double tap. generalized and applied to any mobile device based on a touch-screen. Thus, the results of this work could be usefulFurthermore, it is worth noting that one of the most to developers of mobile operating systems and applicationscommon obstacles, particularly for novice users, is being based on a touch-screen, in addition to those working onable to successfully perform a double tap. This difficulty designing and developing assistive technologies.occurs when the time between the two taps is too long, orwhen the second tap is performed in a different position on Herein we have presented and discussed the resultsthe screen. As a result, these users made a large number of obtained through a user test conducted with 20 blind userserrors when selecting elements using a double tap. Instead in order to evaluate mobile interaction using the proposedthey achieve the correct result with a single tap. prototype.For text insertion, 3 users suggested that it would be useful Comments from the users while interacting with theto have a list of predefined messages, which could be prototype, as well as collected data when performing a setmodified to include customized information. of tasks were encouraging. Positive feedback was also observed by the researchers as regards the intuitiveness andEleven users think that the qwerty keyboard is difficult to ease of use for those people who had never used a touch-use and this opinion was unconnected to the editing screen before. Based on the data and suggestions collectedmodality chosen. For all of them this was due to the we can begin to outline certain aspects and featurespositioning of the keys too close together, which preferred by the users. These should be considered in theconsequently prevented easy identification. User Interface as well as in assistive technology design . InRegarding the phrases and words used by the voice (i.e. to particular we evaluated and collected positive impressionsread the UI labels), the average value obtained is M:4,63. and comments on the usefulness of the following UISome users suggested making the labels more context- features:dependent. For instance, the "Done" button could be • The four action/function buttons at the corners of the touch-screen, such as “Back” and “Done/OK”.
  8. 8. This kind of feature located in fixed places can ACKNOWLEDGMENTS improve user interaction. The authors wish to thank to all people who participated in the user testing and the Italian Association for the Blind for • The assistive technology functions to use in order the collaboration in the organization of the four meetings. to obtain information on the current status. Examples are the “Position” button to find out the REFERENCES location, or the “Repeat” button used to easily read 1.Benedito, J., Guerreiro, T., Nicolau, H., Gonçalves, D.: the focused element (especially for the edit fields The key role of touch in non-visual mobile interaction. In to check what has been written). Specific buttons Proc. of MobileHCI10, ACM, NY, 379-380 or gestures can be a worthwhile solution. 2.Brewster, S.A., Chohan, F., Brown, L.M.: Tactile • Vibro-tactile and tactile support to improve Feedback for Mobile Interactions. Proc. CHI’07. ACM perception of given events (e.g. to confirm action) Press Addison-Wesley, pp 159-162 as well as identify UI parts or elements (e.g. UI 3.Omissed for blind review. macro areas or the focused edit field). 4.Kane, s. K., BiGHAM, J. P., AND Wobbrock, J. O.: Slide • The fully perceivable numpad as an alternative or Rule: Making mobile touch screens accessible to blind an addition to audio number vocalization. Vibro- people using multi-touch interaction techniques. Proc. of tactile support to differentiate between the ASSETS’08. ACM Press (2008), 73-80 numbers (e.g. odd and even) with different frequencies is a possible direction. 5.Kane, S.K., Wobbrock, J.O., Ladner, R.E.: Usable gestures for blind people: understanding preference andThe study [5] suggests that blind subjects prefer gestures performance. In Proc. of CHI 11, ACM. 413-422that use screen corners, edges, and multi-touch (enabling 6.Koskinen, E., Kaaresoja, T., Laitinen, P.: Feel-goodquicker and easier identification) and identifies new touch: finding the most pleasant tactile feedback for agestures in well-known spatial layouts (such as a qwerty mobile touch screen button. Proc. of ICMI08. ACM, Newkeyboard). With regard to the four buttons placed at the York (2008), 297-304corners, our study confirmed that blind users appreciatethese UI elements which are easy to locate or the fact that 7.Omissed for blind review.they are perceivable (e.g. vibro-tactile feedback). In 8.Manshad, A.S.: Multimodal vision glove forcontrast practical problems are encountered when editing touchscreens. Proc. of Assets08, ACM Press (2008), 251-with a qwerty keyboard, even though the layout of the keys 252is well-known to the user. A specific user test based on 9.Oliveira, J., Guerreiro, T., Nicolau, H., Jorge, J.,vibro-tactile numpad will make it possible to collect Gonçalves, D.: BrailleType: unleashing braille over touchadditional and more precise information on vibration usage screen mobile phones. Proc. of Interact 2011as accessibility support in order to overcome the difficultiesassociated with a virtual numpad. More generally, the 10.Shaik, A.S., Hossain, G., Yeasin, M.. Design,evaluation confirmed that editing is still a challenge for a development and performance evaluation of reconfiguredblind person, as already pointed out in the task completion mobile Android phone for people who are blind orresults, where the task T4 is successfully terminated only by visually impaired. Proc. of the 28th ACM SIGDOC 10half of the users. So further investigation is necessary in 11.Wobbrock, J.O., Kane, S.K., Gajos, K.Z., Harada, S. andorder to identify how to improve text editing and numpad Froelich, J.. Ability-based design: Concept, principlesaccessibility. and examples. ACM Trans. Access. Comput., 2011.

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