Interactive Opinion Polls on PublicDisplays – Studying PrivacyRequirements in the Wild

Matthias BaldaufVienna University ofTechnologyWiedner Hauptstr. 76/2/21040 Vienna, Austriamatthias.baldauf@inso.tuwien.ac.at

Ulrich LehnerFTW TelecommunicationsResearch Center ViennaDonau-City-Strasse 11220 Vienna, Austrialehner@ftw.at

Stefan SuetteFTW TelecommunicationsResearch Center ViennaDonau-City-Strasse 11220 Vienna, Austriasuette@ftw.at

Peter FrohlichFTW TelecommunicationsResearch Center ViennaDonau-City-Strasse 11220 Vienna, Austriafroehlich@ftw.at

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AbstractInteractive opinion polls are a promising novel use case forpublic urban displays. However, voicing one’s opinion atsuch a public installation poses special privacyrequirements. In this paper, we introduce our ongoingwork on investigating the roles of the interactiontechnique and the poll question in this novel context. Wepresent a field study comparing three different votingtechniques (public touch interface, personal smartphoneby scanning a QR code, from remote through a short Webaddress) and three types of poll questions (general,personal, local). Overall, the results show that activelycasting an opinion on a timely topic is highly appreciatedby passers-by. The public voting opportunity through atouch screen is clearly preferred. Offering mobile orremote voting does not significantly increase the overallparticipation rate. The type of poll question has animpact on the number of participants but does notinfluence the preferred interaction modality.

Author KeywordsPublic display; public poll; mobile interaction; privacy

ACM Classification KeywordsH.5.2 [Information interfaces and presentation (e.g.,HCI)]: User Interfaces.

IntroductionNowadays, public screens have become ubiquitous inmodern city landscapes and enable a plethora ofinteractive urban applications for passers-by. Onepromising use case which is recently gaining increasinginterest in academia are citizen participation tools such aspublic opinion polls exploiting urban screens asbidirectional communication channel for identifying anddiscussing matters of urban governance.

While previous respective research in the field of publicdisplays focussed on studying social phenomena aroundsuch installations, on investigating how to raise awarenessfor provided interactive applications or on exploring novelinteraction techniques, knowledge about the privacyrequirements and concerns for opinion polls on publicdisplays is scarce. In this paper, we introduce our ongoingwork on privacy aspects in the context of interactivepublic polls and present the results of a preliminary fieldstudy which compared the acceptance of a public votingtechnique and personal smartphone-mediated one andfurther investigated the impact of different categories ofpoll questions on the preferred interaction style and theparticipation rate.

Related Work and Research QuestionsOne of the earliest prototypes utilizing a large publicdisplay for citizen feedback is Opinionizer by Brignull andRogers [3], an interactive shared display where passers-bycould add their views using a keyboard. Two field studiesshowed that social embarrassment is the major deterrentpreventing people from participating. Further, an easychange from being an onlooker to a participant and backagain should be enabled. More recently, interactive publicdisplays have been rediscovered as enabler for civicengagement. For example, TexTales [1] is an opinion

forum on large public projection screen and enabledcommenting of displayed photos through submitting textmessages which led to active offline discussions among theparticipants. Agora 2.0 [7] is another example for aninteractive public display where passers-by could vote forcity-related suggestions through a connected mouse.Related is the idea of Behrens [2] who investigatedtangible (dis)like buttons to express opinions at relatedreal-world locations.

Paek et al. were among the first who investigated mobiledevices as remote controls for shared displays andidentified polling as one promising use case promotingdiscussion and consensus building [5]. A first respectivereal-world example is MobiLenin by Scheible andOjala [6]. Their system enabled guests of a restaurant tovote for video tracks to be played on a large display andincluded a lottery mechanism to win a voucher. Mostrelated to the work presented in this paper isViewpoint [8], a custom device providing a simple votinginterface with two buttons to answer yes/no questions anda small display showing the current result. The prototypefurther featured voting by sending text messages, yet, thisfeature was not used by single participant during the trial.Overall, Viewpoint was very successful in engagingparticipants and received positive feedback.

Having studied the aforementioned literature, weidentified several open questions concerning the privacyrequirements of such public opinion polls and formulatedthe following research questions to be investigated:

1. Is a state-of-the-art mobile interaction techniquesuch as scanning a QR code accepted for privatelycasting a vote through the personal smartphone?

Figure 1: The screen design contained the poll question, a bar chart as wellas an animated banner and short instructions on how to participate.

Figure 2: The prototype was deployed in the entrancearea of a coffee house for 10 workdays.

2. Does the type of poll question (such as general orpersonal) influence the participants’ choice of theparticipation technique?

3. How do participants perceive the opportunity toactively express their opinion at public locations incomparison to just seeing real-time opinionsummaries?

Study PrototypeTo study these research questions under real-worldconditions we developed a functional study prototypebased on state-of-the-art Web technologies. The Webapplication (run in a modern browser in full-screen mode,see Figure 1) showed a poll question in the top center andthe current poll result in form of a bar chart below.Further, it contained an animated banner in the top leftcorner asking passers-by to participate and three shortinstruction texts (with arrows pointing to the respective

input method) explained the three interaction techniquessupported by the prototype:

• Public touch-based voting. A tablet computermounted in front of the large display through acustom-made fixation showed buttons for the threeavailable choices. Passers-by could simply cast theirvote (obviously visible to nearby bystanders) bydirectly touching the respective button (seeFigure 2).

• Private voting on the personal device. To enableprivate voting we showed a QR code on the screen.An interested passer-by who captured the code withhis smartphone was forwarded to a web page wherehe could cast his vote by clicking the correspondingbutton.

• Voting from remote. We further included a shortURL for people who notice the public poll, yetprefer to cast their vote from remote, e.g. whenbeing back at their working place and having lookedup background information. Additionally this optionis suitable for smartphone users, who do not have aQR code reader app installed. The type ofend-device (desktop or mobile) was logged.

To investigate the impact of different questions types, weselected 12 timely poll questions from three differentcategories: locally relevant as the typical question categoryfor participative applications (e.g. Do you wish for moreshops in this area? ), personal (e.g. Are you content withyour current working situation? ), and general ones (e.g.Do you prefer car-free city centers? ). The question on thedisplay was switched in intervals of 15 minutes and wasalternately selected from one of the three categories.

MethodologyWe deployed the described prototype at a coffee shop(Figure 2) for 10 workdays. The shop is located in abusiness district and is visited by about 200 guests perday. In order to collect contextual data, a test assistantobserved the interactions of visitors with the poll systemand made notes using a prepared code sheet containingthe type of interaction and the number of involvedpersons. In the second week, the test assistant handedout questionnaires. They contained general questionswhether the participant liked the possibility to share hisopinion on a current topic of interest through a publicdisplay and to see interim results, respectively, both on 5point Likert scales. Further we wanted to know whetherhe had explicit privacy concerns when participating insuch a poll on a public display.

Figure 3: Participant ratings concerning the statements ’I liketo share my opinion/see the opinion of others on a currenttopic on a public screen’.

ResultsDuring the ten days we recorded 160 votes (participationrate about 8%) and received 30 completed questionnaires.The interviewees (12 females) were aged between 14 and76 (mean=38.7, median=38).

Log file analysisThe analysis of the log file yielded a very clear result: werecorded only one voting through the QR code and oneusing the URL (on a mobile device). 99% of the voteswere casted by directly touching the tablet. Concerningthe type of polls, 43% of the votes were given for generalquestions, 33% for locally relevant ones, and 24% forpersonal questions.

QuestionnaireFour of 30 interviewed persons stated they have privacyconcerns. Two of them explicitly mentioned the possibilityof a fingerprint sensor integrated in the touch screen. Themost common explanation in the group without privacyconcerns was that the poll is anonymous and no privateinformation is entered.

48% and 33% of the participants stated to fully agree andto agree, respectively, with the statement ’I like to sharemy opinion on a current topic on a public screen’. 15%were undecided and 3% disagreed. The second statement,’I like to see the opinion of others on a current topic on apublic screen’ was answered by 36% with strongly agree,30% with agree and 6% with disagree. 27% wereundecided. For both statements, no participant fullydisagreed.

ObservationsIn addition to well-known phenomena such as the“honeypot effect” [3] (passers-by being attracted bypeople already interacting with the display) and the“landing effect” [4] (people pass the display, stop late andwalk back), we observed several particular social effectswhich partly confirm experiences from recent relatedstudies (e.g. [9]):

Encouraging colleagues. Several times only one memberof a group (such as workmates) noticed the public pollwhen passing by and – accepting to unveil his choice –encouraged his colleagues to vote as well.

Social deterrence. We counted less interactions with thepoll screen when the table close to the screen wasoccupied by visitors and noticed several people who wereobviously interested in the poll but turned away from thescreen.

Discussions with by-standers. Often discussions about thepoll topic arose, not only between persons of one groupbut even among visitors who obviously did not know eachother before.

Waiting times. In peak times a waiting queue developedin front of the counter. While standing in the queue,

several visitors used the public poll to bridge the waitingtimes. Due to this waiting situation, they were obviouslymore engaged in the interaction with the public screen.

DiscussionIn this section we refer back and relate the results to ouroriginal main research questions. The results of our fieldstudy showed that even for opinion polls in a public settinga direct interaction (in our case through a touch-sensitivetablet computer) is clearly favored over the opportunity touse the personal smartphone for privately submitting avote. Offering the QR code as a state-of-the-art mobileinteraction technique did not lead to significantly moreparticipants. While we expected the overall result, thedecidedness is surprising. We avoided a native voting appwhich would need to be downloaded and chose a modernmobile interaction technique (plus a short URL) overold-fashioned texting (cf. [8]) and thus assumed thatseveral participants would use their smartphones forprivately casting their vote, especially in the case ofpersonal questions. However, we saw that people who didnot want by-standers to observe their voting behavior didnot choose to use their smartphone (or the remote votingopportunity), but decided not to participate at all. Thetype of question (local, personal, general) did not haveany significant impact on this behavior.

The distribution of votes to the different poll categories isexplicable: we expected that personal questions wouldreceive fewest votes due to the public setting. We assumethat general questions attracted most participants sincethe study environment is not only visited by employees ofnearby companies but also by external guests and businesspartners who were less interested in locally relevant topics.The responses to our questionnaire showed that themajority of the participants liked the idea of using public

displays for polls in general. The slight trend thatparticipants enjoyed more to actively express their opinionthan to see the interim results is explained by participants’comments appreciating the opportunity to raise the voiceand the feeling of being heard.

Conclusions and OutlookWe presented a preliminary field study which serves as astarting point to investigate privacy aspects concerninginteractive public opinion polls in more depth. Our resultsclearly show that mobile interaction opportunities, even anadvanced one like in our study, are largely ignored asprivate voting techniques, when direct touch interactionat the public display is provided as an alternative inputmethod. The type of poll question (general vs. personal)has an impact on the number of participants to beexpected, however, not on the preference for the directvoting technique.

As a conclusion, current mobile voting features can beneglected when realizing a public poll application whichalso features a direct voting technique, since they are notcapable of significantly increasing the number ofparticipants. To reach a higher participation rate also forpersonal questions, an open challenge is the design ofnovel voting techniques which are comparable to a directtouch interface in terms of simplicity and speed but stilldo not reveal the participant’s choice when used in public.

AcknowledgmentsThis work has been carried out within the JPI UrbanEurope project b-Part financed by FFG, Tekes andFormas. FTW GmbH is funded within the programCOMET - Competence Centers for Excellent Technologiesby BMVIT, BMWA, and the City of Vienna. The COMETprogram is managed by the FFG.

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