Eronen, L. (2003) User Centered Research for Interactive ...lib.tkk.fi/Diss/2004/isbn9512273225/article7.pdf · Eronen, L. (2003) User Centered Research for Interactive Television

Eronen, L. (2003) User Centered Research for Interactive Television. In Proceedings of the 2003 EuropeanConference on Interactive Television: From Viewers to Actors (April 2-4,Brighton, UK), University of Brighton, 5-12.

User Centered Research for Interactive Television

Leena Eronen

Telecommunications Software and Multimedia LaboratoryHelsinki University of Technology

P.O.Box 5400, FI-02015 HUT, Finland+358 9 451 5130

[email protected]

AbstractThis paper presents results from a qualitative user study. The aim of research was to include the futureusers of a new technology in the product design of interactive television programs. During the study, thestudy participants were interviewed. They were asked to answer questions about their television use andto comment on artist’s drawings presenting the possible future setup and equipment at home. The studyresulted in users’ stories and innovations of interactive applications for the future.

KeywordsUser centered research, interactive television, users’ stories

IntroductionSome reported studies on user centered productdesign for the television will be described herenext. For example, users have been included in thedesign of an integrated television and VCR[Petersen et al., 2002], a set-top-box [O’Brien et al.,1999] and on-screen displays, remote controls anda satellite dish [Logan 1994]. There are also resultsfrom usability testing interactive multimediaservices [Hvannberg & Larusdottir, 2000],Electronic Program Guide prototypes (EPGs)[Eronen & Vuorimaa, 2000] and interactivedocumentaries where the user can select a paththrough the documentary [Nardon et al., 2002].Attempts to move from usability testing tocollaborative design has resulted in new methodsand tools. For example, designing access to PCfunctionality and applications through a TV sethas led to the development of cooperative toolsfor creation of ideas [Bødker et al., 2000].

In addition to qualitative methods, quantitativemethods also reveal information on the real use ofthe product. An example of a quantitative userstudy was conducted to evaluate a Web-basedEPG [Smyth & Cotter, 2000]. Here the contentpersonalization system learned from user’s onlineactivity at a given Web site and automaticallyconstructed a profile for filtering information forthe user. Also log file data from actual Web usagehas been used in designing an EPG with a lowentry barrier [Baudisch & Brueckner, 2002]. There

is also a quantitative user study conducted in thehome environment that included approximately500 TV viewers [Gauntlett & Hill, 1999]. Theirresponses to questionnaire-diaries on their life andtheir television watching were collected for over afive-year period.

Leisure Time Activities and the HomeEnvironmentStudies in the home environment are important asthe use of consumer products is in many waysdifferent from the use of products aimed to beused mainly at work. For example, watching thetelevision as a leisure time activity is notcomposed of tasks to be accomplished or distinctgoals to be achieved as is the case with manyactivities in the working life.

Qualitative user studies reveal information on thenature of TV viewers’ leisure time and the homeenvironment. An example of a qualitative userstudy conducted in the home environmentrevealed that technology was routinely used in avariety of different ways within the home[O’Brien et al., 1999]. The harmoniouscoordination of everyday domestic activities wasbased on sophisticated understanding of familymembers’ activities and uses of technology as isthe use of the television or radio. The studyrevealed ethnographic data and an evaluation of aprototype set-top-box for the provision of digitalservices to the home.

Another long-term empirical study of televisionuse in the home environment revealed that the use


of new technology continously develops in acomplex interplay between the user’sexpectations, user’s needs and the context of use[Petersen et al., 2002]. The devices at home areintegrated parts of physical devices with uniquekinds of interfaces and their use is shared.

User Centered ResearchIn the early stages of user centered research, therewas a tendency to include the future users in theproduct development in the very final steps ofnew product design. User feedback waswelcomed during usability testing sessions, longpast the completion of the initial design stages of anew technology. Usability testing helps to find theusability problems, but a lot of effort is saved byconducting usability testing already in the earlystages of new product development. In these earlystages, the final product can be simulated withlow-fidelity prototypes such as drawings,scenarios or paper mockups. It has been foundthat low-fidelity prototypes are as efficient indetecting usability problems as is the final high-fidelity prototype [Virzi et al., 1996].

Usability testing of existing devices does not,however, tell directly which new technologiescould help meet the users’ future needs. To obtainmore information on user needs and users’ realworking environments, researchers arrange fieldtrips. During the field trips, researchers observeusers using technology tools in their authenticcontexts of use, either at work or at home.Ethnographic research is based on field tripswhere the aim of research is to develop athorough understanding of users’ current workpractices or leisure time habits. If the researcherscan’t visit the users, the users can collect the datathemselves and then send it to researchers. Forexample, users can participate in the datagathering by taking photographs [Eronen, 2002aand Gaver et al., 1999] or they can write diariesand answer to questionnaires [Eronen, 2002a,Gauntlett & Hill, 1999 and Gaver et al., 1999].

Interviews, Focus Groups and Users’StoriesUsability testing and ethnographic research aregood methods for obtaining user data andfeedback from users. There is however a gapbetween field studies and design, or user

Figure 1. A study participant during an interview.

requirements and design. To overcome this gapand to provide examples of future productconcepts to designers, there is a need for researchmethods that enable the users themselves toinitiate new ideas. A simple approach is toconduct interviews or focus group sessions withthe future users of a new product, asking for theiropinion on a set of questions during a structuredor a semi-structured conversation. The results arethen analyzed to find important examples anduser experiences [Rubin & Rubin, 1995].

An important result from interviews and focusgroup studies is users’ stories. Stories describeusers’ intentions and motives, their interactionsand the contextual information [Imaz & Benyon,1999]. Stories may have many viewpoints and acomplex structure as the changing of viewpointmay imply some future consequences of earlyactions. Users’ stories are able to inform thedevelopment of new products by providing users’own design ideas [Taylor & Harper, 2002]. Storiesand storytelling made by designers themselveshelp to model and design HCI systems [Erickson,1995].

MethodsThe qualitative user study presented here nextconsists of four interviews with TV viewers. It is acontinuation on studies resulting in new conceptsof interactive television programs made by ten TVviewers [Eronen, 2002a] and ten designers in abroadcasting company [Eronen, 2002b]. Fourstudy participants in the age range of 29-37 yearsparticipated in the study. Two women and twomen answered a set of questions


Figure 2. Artist’s view of the living room in thefuture.

during the interviews which took 80-110 minuteseach (cf. Figure 1). The interviews were recordedfor later inspection and the results are presentedin the next section.

In the beginning of an interview, three “Artist’sview of the future” drawings were shown to astudy participant (cf. Figures 2, 3, 4). A semi-structured conversation followed. The studyparticipant was asked to comment on thedrawings presenting the possible future setup andequipment in different locations at home.

None of the study participants had yet purchaseda digital set-top-box for themselves and theydidn’t know what the present services andapplications look like. In general, the studyparticipants first wanted to see the new digitalservices to be of use to them before purchasing aset-top-box.

The reason for using artist’s drawings instead ofphotographs or pictures of present services is thatwe wanted to give more freedom to studyparticipants to relate to their own past experiencesand wishes when considering their future needsand preferences. It was easier to talk about thestudy participants’ future needs when they werenot provided with images of what is alreadyavailable.

The second part of the interview dealt withselected new TV program concepts designed in abroadcasting company beforehand. This part ofresearch serves the needs of product developmentof that broadcasting company, and the results aretherefore not available here.

ResultsThe interview results are presented here next. Forthe purposes of this paper, the 26 pages ofinterview results were shortened substantially. Allstudy participants’ names were changed to protectprivacy. As the interviews were conducted inFinnish, the quotations shown in this paper weretranslated into English.

Susan, a 30-year old physiotherapist answeredquestions about which TV program types couldbecome important in the future:

Q: “The television in the future will havesomething for everyone. In your opinion, whattype of TV programs there will be?”

A: “I could think that (some channel) would broadcastmore, all types of, historical material, from the recenthistory. It could create more interest (among the TVviewers) in the (historical) issues in the future.”

Q: “In your opinion, what type of TV programscould bring the family together to watch a TVshow?”

A: “As a family, we could watch Nature seriestogether. Children get interested in them as well. Andas funny as it might sound, I’m myself interested inSports. The soap operas are something I couldn’t thinkof watching at together with the children.”

Andrew, a 29-year old elementary school teacheranswered questions about the future equipment inthe living room (cf. Figure 2):

Q: “Here is a drawing of the living room in thefuture. In your opinion, is this a realistic picture?”

A: “I doubt about the father’s pleasure to watch themovie, or the sports event, next to these childrenplaying the TV games. I play the PlayStation2 gamesmyself and as I know the resulting side tones, well..Maybe you wouldn’t enjoy watching the TV show asclose (to children) as this. And furthermore, I can’tafford to as much equipment as you see in the picture.”

Andrew also had an opinion on the present andfuture TV shows:

“I believe that in principle people want to watch thesame type of TV shows as they do today. They want tosee News and Sports, maybe some series, some of whichare more entertaining and some of which are more intoculture.”

“The children are a large market niche, they willcertainly get new types of TV programs. You alreadyhave the ‘product family’ TV programs. You must buychildren’s toys according to the TV series, and clothes.Probably you’ll get more of these.”


Figure 3. Artist’s view of the work room at homein the future.

Andrew answered a question about what thework room at home could be like in the future (cf.Figure 3):

Q: “What type of TV programs could one watch atin the future in the work room if there was a TVset?”

A: “School kids could have it as a homework to watch ashort movie. They could watch it (in the Web) whenthey have time. Today at shool, I show them “SchoolTV Programs” in Finnish. 10-11 year-olds can follow aforeign program with subtitles. But with subtitles,most students loose the track of the TV show if thesubject is difficult. (Therefore) I prefer to show themFinnish programs.”

Susan answered questions about having a TV setin the kitchen (cf. Figure 4):

Q: “In the kitchen, what type of TV programscould one watch at in the future?”

A: “We don’t spend that much time in the kitchen, andin my opinion, you don’t watch TV when you arehaving a dinner. In general I think it would be quitefragmental to watch TV in the kitchen, maybe whileyou are having a quick snack.”

“As for today, we see the living room TV while we areat the kitchen table. The only reason for me to buy a(separate) TV set for the kitchen would be the twoMorning TV Shows which we surf intensively. Wewatch the two shows according to the topic, and surfbetween the two channels. I can’t think of any otherprogram we would watch at in the kitchen.”

“In the Morning TV Show, I want to see short Newsand if there are any interesting visitors in the studio. Inmy opinion, you could leave out the Cuisine

Figure 4. Artist’s view of the kitchen in the future.

programs shown on TV in the morning. They take toolong. Who has the (time and) energy to write down therecipes?”

Helen, a 37-year old woman with a Master'sdegree in Economics, also answered questionsabout having a TV set in the kitchen:

“For example, let’s assume these people (in the picture)are a retired couple. You could have a schedule (in theTV) for the day, (a list of things or some work) youmust do after the morning routine. If you have to paythe bills, then (the program) gives you a reminder onthe screen: ‘Remember to pay such and such a bill’,‘Water the plants’ or ‘Order something (online)’.”

“I could think of (an interactive) program that helpsyou with the practicality, and (where) you could writedown something for yourself in some free space. Or youcould do scheduling for the coffee machine or the oven,if (everything) is connected to the set-top-box. I use thescheduling function a lot in my mobile phone. I couldas well use it in my TV. If we go into very automatic(style of life), (the program) could tell you what to havefor a dinner, and it then reminds you to buy certainingredients.”

Innovations of Interactive Applicationsfor the FutureDuring the discussions, the study participantscreated innovations of interactive applications forthe future. Some of them are presented here next.

The user interaction needed to make a televisionprogram interactive can take place either directlyor indirectly. Direct user interaction takes place infour different ways. Users’ opinions and answerscan be sent to the TV show with the remotecontrol and a modem in the set-top-box, or there


can be an SMS sent from a mobile phone, a phonecall or a postcard sent to the TV show.

Indirect user interaction takes place when usersvisit Web pages or Teletext pages of the programduring or after the TV show. Users do this to getmore information on a chosen topic but they don’tnecessarily send their opinions to the TV show.Therefore they don’t have a direct interaction withthe TV show or the other users.

Helen’s example of an innovation with direct userinteraction is as follows: “I suggest that in the futurechildren will have more programs related to theirgames and hobbies. The home is a place where childrendo things together (with adults and other children). Itwill be a counterbalance (in children’s lives) toeverything else, and machines will help in that. Anexample is a program based an interactive adventurethat has a well defined plot. This is for the olderchildren, the youngest ones can’t possibly take part inthat.”

“Then if we think about the Web use or the use of amouse, children could solve drawing tasks with aninstant feedback. Truly, I have thought about it, itcould be very important for many children. Especiallyif you don’t get (such) feedback from the school orpreschool you want. There could be a connection to theWeb or some game (in the set-top-box) and severalchildren in the family could play it together. Olderchildren could help instruct the younger. During theprogram, you get a point and a verbal feedback, ‘Youhave succeeded’ or ‘Wow, what a lovely drawing’.”

Susan created an innovation with indirect userinteraction: “I work at a health club and I would liketo see (an interesting) Fitness program on TV. Thetopics discussed in the program would cover fitnessand health issues, taking exercise and where to go toexercise a certain new form of physical activity. I’malso interested to hear what is happening in the healthclubs in other parts of the world as this is part of myjob description. I could think of watching a TV showshooted in a famous health club in US and taking noteson what they have there and what we don’t yet havehere. It is fine for me to see the program only once aweek or twice a month, not every day.”

In this case, it would be easy to launch a Webbrowser and visit the Web pages for the programon the TV screen after the TV show. The Webpages would include photographs and links to thehealth clubs presented earlier in the show.

Helen created an innovation with indirect userinteraction: “I suggest that the Morning TV Show(s)will survive. For many, (to watch the program) hasbecome a certain kind of a ritual. At least, you watchthe Morning News. (In the future) it could be that the

program takes only a portion of your TV screen. Thereis (many) different ‘boxes’ on your screen and one ofthem contains News. You don’t have to open it upcompletely, (the screen) looks like a computer screenwith various windows. You would also see stock ratesrunning along. In some corner there could be a list ofthe TV programs for the day, just to see there isnothing unusual.“

Austin, a 29-year old lawyer created aninnovation with indirect user interaction: “I’ll takea hiking trip to north of Finland next month. (If thereexisted a program on nature tourism and) if it had aconnection to something I’ll do myself, I could go totheir Web pages. I haven’t followed programs ontraveling much but if I had it in my plan to travelsomewhere, then I could go (to their Web pages) to seeif they come close to what I had in my plan.”

DiscussionThe qualitative user study presented in this paperwas based on a semi-structured conversation withusers. The semi-structured conversation is amethod for focus group sessions. Here it helpedthe study participants to discuss about their futureneeds and preferences.

The study participants found it easy to talk aboutthe TV shows they were interested in to see in thefuture. They innovated new applications thatwould provide them more information andentertainment in areas they were interested in.

However, the study participants found it easier toinnovate for the ‘living room TV’ than the ‘workroom TV’ or the ‘kitchen TV’. This might depictthat watching the TV is considered more as asocial activity to be shared with other familymembers in the living room, and the individualspaces as the work room don’t attract the familymembers to spend their leisure time as much asthe living room.

Future Work in Home EnvironmentThree “Artist’s view of the future” drawings wereshown to study participants who then relatedstories from their own experiences. Studyparticipants considered their future needs andpreferences for interactive applications in eachroom separately: the living room, the work roomand the kitchen.

The equipment at home and the separate roomshave already been a subject of research in severalstudies. For example, it has been found that thehome environment and the daily routines create‘behavioral clusters’ [Mateas et al., 1996]. Familiesspend most of their time in so called ‘commandand control’ or ‘hangout’ spaces, which imply to


the living room and the kitchen. Many activitiesare characterized as communication to supportemotional bonding rather than carrying out giventasks.

There are also results from designing socialcommunication devices for the home [Hindus etal., 2001] and a study of the technology use andthe internal structure of the household-technologyinteraction [Venkatesh, 1996]. These results implythat the relationship between technology and oursocial world is important and needs moreattention.

The ‘possible future setup and equipment athome’ presented in this paper in the artist’sdrawings is already a reality for some families. Itis common today to have a living room TV, aseparate TV in every bedroom and the kitchen,and several VCRs. The different types of usecontexts at home result in different types of userneeds. In the future, this might result in the designof specified interactive applications for specifiedtypes of TVs. Therefore, more research is neededto discover the user needs and user’s tasks in thedifferent use contexts these entertainmentequipment must support.

User Interaction and System’sResponseAn interesting research area for the future arisesfrom the user interaction. Namely, human-to-human interaction follows the social conventionsfor real-time interaction. A conversation, and alsothe process of dialog itself can be valuable, notjust the results of the conversation. This is due tosuccessful exchanges of information about theparticipants’ attitudes and feelings which changemoment by moment during the conversation.

Signals that express our emotions are often non-verbal and generally sent and received withoutconscious attention. PC and Web-basedtechnologies don’t usually handle this type ofcommunication, focusing on the exchange ofinformation. Therefore, the human aspects of real-time social interaction and the modelling of user’semotional states are an interesting research area[Tsukahara & Ward, 2001].

It is not yet known how human-computerinteraction of the entertainment technologies forthe home environment handles this type ofcommunication. However, it was found in a seriesof media studies that people responded to TV andthe mediated presentations as if they were actualpeople and objects [Reeves & Nass, 1996]. Forexample, in study participants’ opinion, the TV

news segments seen on a TV set labeled ‘NewsTelevision’ were significantly more important,informative, interesting and serious than the samenews segments on a TV set labeled ‘News andEntertainment Television’. It was concluded thathuman beings assign social roles (specialist,generalist) to media to reduce uncertainty abouttheir world.

The entertainment technologies for the homecould emulate some aspects of real-time socialinteraction and people’s roles during theinteraction, in which case they would make userinteraction more pleasant, sympathetic andsupportive.

ConclusionThe user study presented in this paper is anexample of a qualitative user study including thefuture users into the product design. The studyparticipants were interviewed and they wereasked to comment on artist’s drawings presentingthe possible future setup and equipment at home.

In general, it is difficult to discuss about non-existing future devices or applications. The use ofartist’s drawings instead of pictures of presentservices enabled the study participants to relate totheir own experiences from their past televisionuse. It was easier to talk about study participants’future needs and preferences when they were notprovided with specific images of services alreadyavailable.

The study resulted in users’ stories on theirtelevision use and their innovations of interactiveapplications for the future. Many of theinnovations in the subsection ‘Innovations ofInteractive Applications for the Future’ are quiteclose to written scenarios. It is possible to combineusers’ stories and edit them further to makelonger scenarios. For example, a set of storiescould exemplify “An afternoon at the Jones’s”where every family member has a story to tell.Here short stories put together make a largerscenario.

New user requirements can also be extracted fromusers’ stories. The drawback of using users’ storiesis the transcription of the interviews which takes alot of time. The rewards in users’ stories is thatthey are the ‘authentic voice of the users’. Forexample, during participatory future-scenarioworkshops the future users are given new ideasby the designers and researchers which then moldtheir opinions about their possible futures.Meanwhile during an interview, the user hasmore freedom to talk about his own experiences


that are of importance to him. During a workshop,the user faces more social pressure that forexample makes it uncomfortable for him to airdissenting opinions.

It is concluded that much of what people do issocially driven and based on communication. Thedesign of new devices and interactive applicationsfor the home environment must take into accounthow people use and understand the newtechnologies as part of their everyday activities.

AcknowledgmentsThe author would like to thank the user studyparticipants for providing their time and help forthe research, and Master of Arts student RiikkaKevo for the three “Artist’s view of the future”drawings. The author has received a scholarshipfrom YLE 75 Years Fund (YLE - FinnishBroadcasting Company).

ReferencesBaudisch, P. & Brueckner, L. 2002. TV Scout:Guiding Users from Printed TV Program Guidesto Personalized TV Recommendation, inProceedings of the 2nd Workshop on Personalization inFuture TV (May 28, Malaga, Spain), Universidadde Malaga, 157-166.

Bødker, S., Nielsen, C. & Petersen, M. G. 2000.Creativity, Cooperation and Interactive Design, inConference proceedings on Designing interactivesystems DIS ‘00: processes, practices, methods, andtechniques (August 17-19, Brooklyn, NY, USA),ACM Press, 252-261.

Erickson, T. 1995. Notes on Design Practice:Stories and Prototypes as Catalysts forCommunication, in Carroll, J. M. (ed.) Scenario-Based Design: Envisioning Work and Technology inSystem Development. Wiley, New York, NY, USA.

Eronen, L. 2002a. Design of Future Television, inProceedings of the HF2002 Human FactorsConference, the 1st Joint Conferences of theErgonomics Society of Australia (ESA) and theAustralian CHISIG (November 25-27, Melbourne,Australia), 8 pages.

Eronen, L. 2002b. Design of Interactive TelevisionPrograms, in Proceedings of the 3rd Annual ACMSIGCHI-NZ Symposium on Computer-HumanInteraction CHINZ 2002 (July 11-12, Hamilton,New Zealand), ACM SIGCHI_NZ, 73-78.

Eronen, L. & Vuorimaa, P. 2000. User Interfacesfor Digital Television: a Navigator Case Study, inProceedings of the Working Conference on AdvancedVisual Interfaces AVI 2000 (May 23-26, Palermo,Italy), ACM Press, 276-279.

Gauntlett, D. & Hill, A. 1999. TV living: Television,culture and everyday life. Routledge, London,United Kingdom.

Gaver, B., Dunne, T. & Pacenti, E. 1999. Design:Cultural Probes. Interactions 6, 1, 21-29.

Hindus, D., Mainwaring, S. D., Leduc, N.,Hagström, A. E. & Bayley, O. 2001. Casablanca:Designing Social Communication Devices for theHome, in Proceedings of the CHI 2001 Conference onHuman Factors in Computing Systems (March 31-April 4, Seattle, WA, USA), ACM Press, 325-332.

Hvannberg, E. T. & Larusdottir, M. K. 2000.Usability Testing of Interactive MultimediaServices, in Proceedings of the NordiCHI2000conference (October 23-25, Stockholm, Sweden),NordiCHI and STIMDI, 8 pages.

Imaz, M. & Benyon, D. 1999. How Stories CaptureInteractions, in Proceedings of Human-ComputerInteraction – INTERACT '99 (September 1-3,Edinburgh, Scotland), IOS Press, 321-328.

Logan, R. J. 1994. Behavioral and EmotionalUsability: Thomson Consumer Electronics, inWiklund, M. E. (ed.) Usability in Practice: HowCompanies Develop User-Friendly Products. APProfessional, Boston, MA, USA.

Mateas, M., Salvador, T., Scholtz, J. & Sorensen D.1996. Engineering Ethnography in the Home, inProceedings of the CHI '96 Conference Companion onHuman Factors in Computing Systems (April 13 - 18,Vancouver, British Columbia, Canada), ACMPress, 283 - 284.

Nardon, M., Pianesi, F. & Zancanaro, M. 2002.Interactive Documentaries: First Usability Studies,in Proceedings of the 2nd Workshop on Personalizationin Future TV (May 28, Malaga, Spain),Universidad de Malaga, 79-88.

O'Brien, J., Rodden, T., Rouncefield, M. & Hughes,J. 1999. At Home with the Technology: AnEthnographic Study of a Set-Top-Box Trial. ACMTransactions on Computer-Human Interaction 6, 3,282-308.

Petersen, M. G., Madsen, K. H. & Kjær, A. 2002.The Usability of Everyday Technology: Emergingand Fading Opportunities. ACM Transactions onComputer-Human Interaction 9, 2, 74-105.

Reeves, B. & Nass, C. 1996. The Media Equation:How People Treat Computers, Television, and NewMedia Like Real People and Places, Chapter 12. CSLIPublications, Stanford, CA, USA.

Rubin, H. J. & Rubin, I. S. 1995. QualitativeInterviewing: The Art of Hearing Data, Chapters 3 &


10. Sage Publications, Inc., Thousand Oaks, CA,USA.

Smyth, B. & Cotter, P. 2000. EnablingTechnologies: A Personalized Television ListingsService. Communications of the ACM 43, 8, 107-111.

Taylor, A. S. & Harper, R. 2002. Age-old Practicesin the 'New World': A study of gift-givingbetween teenage mobile phone users, inProceedings of the CHI 2002 Conference on HumanFactors in Computing Systems (April 20-25,Minneapolis, Minnesota, USA), ACM Press, 439-446.

Tsukahara, W. & Ward, N. 2001. Responding toSubtle, Fleeting Changes in the User's Internal

State, in Proceedings of the CHI 2001 Conference onHuman Factors in Computing Systems (March 31-April 4, Seattle, WA, USA), ACM Press, 77-84.

Venkatesh, A. 1996. Computers and OtherInteractive Technologies for the Home.Communications of the ACM 39, 12, 47-54.

Virzi, R. A., Sokolov, J. L. & Karis, D. 1996.Usability Problem Identification Using Both Low-and High-Fidelity Prototypes, in Proceedings of theCHI 96 Conference on Human Factors in ComputingSystems (April 13-18, Vancouver, BritishColumbia, Canada), ACM Press, 236-243.

Documents

Eronen, L. (2003) User Centered Research for Interactive ...lib.tkk.fi/Diss/2004/isbn9512273225/article7.pdf · Eronen, L. (2003) User Centered Research for Interactive Television