Keith Cheverst

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http://www.comp.lancs.ac.uk/computing/staff/kc/
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kc@comp.lancs.ac.uk

Keith Cheverst is a Senior Lecturer in the Computing Department at Lancaster University and has recently held positions as Visiting Research Scientist at Melbourne University and Microsoft Research, Cambridge. For the last 10 years he has participated actively in the areas of Mobile computing, CSCW, HCI and Ubiquitous computing (with his interest in the latter area focussing on the study of proactive systems and situated display based interactive systems). He has served on numerous PCs and published over 80 research publications. He has also co-founded and co-organised a number of international workshops - including: HCI in Mobile Guides (a series of five), User Modelling for Ubiquitous Computing , Ubiquitous and Decentralized User Modeling and Appropriate Methods for Design in Complex and Sensitive Settings . He has presented a number of invited talks, the most recent being a keynote in Melbourne at the Simtech international workshop entitled: “Social Interaction, Messaging to Place and Situated Digital Displays”. He holds a BSc and PhD in Computer Science, both from Lancaster and is the PI of the EPSRC funded CASIDE project.

Publication Statistics

Publication period start
1999
Publication period end
2011
Number of co-authors
71

Co-authors
Number of publications with favourite co-authors

Productive Colleagues
Most productive colleagues in number of publications

Publications

Salovaara, Antti, Hook, Kristina, Cheverst, Keith, Twidale, Michael, Chalmers, Matthew, Sas, Corina (2011): Appropriation and creative use: linking user studies and design. In: Proceedings of ACM CHI 2011 Conference on Human Factors in Computing Systems , 2011, . pp. 37-40. http://dx.doi.org/10.1145/1979742.1979585

Taher, Faisal, Cheverst, Keith (2011): Exploring user preferences for indoor navigation support through a combination of mobile a. In: Proceedings of 13th Conference on Human-computer interaction with mobile devices and services , 2011, . pp. 201-210. http://dx.doi.org/10.1145/2037373.2037405

Taylor, Nick, Cheverst, Keith (2010): Creating a rural community display with local engagement. In: Proceedings of DIS10 Designing Interactive Systems , 2010, . pp. 218-227. http://doi.acm.org/10.1145/1858171.1858209

Schmid, Falko, Hesselmann, Tobias, Boll, Susanne, Cheverst, Keith, Kulik, Lars (2010): SISSI '10: social interaction in spatially separated environments. In: Proceedings of the 2010 International Conference on Uniquitous Computing , 2010, . pp. 501-502. http://doi.acm.org/10.1145/1864431.1864498

Willis, Katharine S., Cheverst, Keith, Mueller, Claudia, Abend, Pablo, Neufeldt, Cornelius (2009): Community Practices and Locative Media. In: Proceedings of 11th Conference on Human-computer interaction with mobile devices and services , 2009, . pp. 105. http://doi.acm.org/10.1145/1613858.1613979

Wilde, Erik, Boll, Susanne, Cheverst, Keith, Frohlich, Peter, Purves, Ross, Schoning, Johannes (2009): Location and the web: (LocWeb 2009). In: Proceedings of ACM CHI 2009 Conference on Human Factors in Computing Systems , 2009, . pp. 4737-4740. http://doi.acm.org/10.1145/1520340.1520729

Taylor, Nick, Cheverst, Keith (2009): Social interaction around a rural community photo display. In International Journal of Human-Computer Studies, 67 (12) pp. 1037-1047. http://dx.doi.org/10.1016/j.ijhcs.2009.07.006

Müller, Jorg, Cheverst, Keith, Fitton, Dan, Taylor, Nick, Paczkowski, Oliver, Krüger, Antonio (2009): Experiences of Supporting Local and Remote Mobile Phone Interaction in Situated Public Dis. In International Journal of Mobile Human Computer Interaction, 1 (2) pp. 1-21. http://www.igi-global.com/Bookstore/Article.aspx?TitleId=4071

Schoning, Johannes, Krüger, Antonio, Cheverst, Keith, Rohs, Michael, Lochtefeld, Markus, Taher, Faisal (2009): PhotoMap: using spontaneously taken images of public maps for pedestrian navigation tasks . In: Proceedings of 11th Conference on Human-computer interaction with mobile devices and services , 2009, . pp. 14. http://doi.acm.org/10.1145/1613858.1613876

Cheverst, Keith, Coulton, Paul, Bamford, William, Taylor, Nick (2008): Supporting (Mobile) User Experience at a Rural Village \"Scarecrow Festival\": A Formative. In: Henze, Niels, Broll, Gregor, Rukzio, Enrico, Rohs, Michael, Zimmermann, Andreas, Boll, Susanne (eds.) Mobile Interaction with the Real World 2008 - MIRW 2008 - Mobile HCI Workshop September 2, 2008, Amsterdam, The Netherland. pp. 27-38. http://mirw08.offis.de/paper/05.pdf

Kray, Christian, Cheverst, Keith, Harrison, Michael D., Hamhoum, Fathi, Wagner, Jürgen (2008): Towards a location model for indoor navigation support through public displays and mobile . In: Henze, Niels, Broll, Gregor, Rukzio, Enrico, Rohs, Michael, Zimmermann, Andreas, Boll, Susanne (eds.) Mobile Interaction with the Real World 2008 - MIRW 2008 - Mobile HCI Workshop September 2, 2008, Amsterdam, The Netherland. pp. 83-92. http://mirw08.offis.de/paper/07.pdf

Taylor, Nick, Cheverst, Keith (2008): \"This might be stupid, but...\": participatory design with community displays and postcar. In: Proceedings of OZCHI08 - the CHISIG Annual Conference on Human-Computer Interaction , 2008, . pp. 41-48. http://doi.acm.org/10.1145/1517744.1517757

Cheverst, Keith, Schoning, Johannes, Krüger, Antonio, Rohs, Michael (2008): Photomap: Snap, Grab and Walk away with a \"You Are Here\" Map. In: Henze, Niels, Broll, Gregor, Rukzio, Enrico, Rohs, Michael, Zimmermann, Andreas, Boll, Susanne (eds.) Mobile Interaction with the Real World 2008 - MIRW 2008 - Mobile HCI Workshop September 2, 2008, Amsterdam, The Netherland. pp. 73-82. http://mirw08.offis.de/paper/04.pdf

Cheverst, Keith, Dix, Alan J., Fitton, Daniel, Rouncefield, Mark, Graham, Connor (2007): Exploring Awareness Related Messaging Through Two Situated-Display-Based Systems. In Human-Computer Interaction, 22 (1) pp. 173-220. http://www.leaonline.com/doi/abs/10.1080/07370020701307955

Cheverst, Keith, Dix, Alan J., Fitton, Daniel, Rouncefield, Mark, Graham, Connor (2007): Exploring Awareness Related Messaging Through Two Situated-Display-Based Systems. In Human-Computer Interaction, 22 (1) pp. 173-220. http://www.leaonline.com/doi/abs/10.1080/07370020701307955

Cheverst, Keith, Dix, Alan J., Fitton, Daniel, Rouncefield, Mark, Graham, Connor (2007): Exploring Awareness Related Messaging Through Two Situated-Display-Based Systems. In Human Computer Interaction, 22 (1) pp. 173-220.

Graham, Connor, Rouncefield, Mark, Gibbs, Martin, Vetere, Frank, Cheverst, Keith (2007): How probes work. In: Proceedings of OZCHI07, the CHISIG Annual Conference on Human-Computer Interaction November 28-30, 2007, Adelaide, Australia. pp. 29-37. http://doi.acm.org/10.1145/1324892.1324899

Taylor, Nick, Cheverst, Keith, Fitton, Dan, Race, Nicholas J. P., Rouncefield, Mark, Graham, Connor (2007): Probing communities: study of a village photo display. In: Proceedings of OZCHI07, the CHISIG Annual Conference on Human-Computer Interaction November 28-30, 2007, Adelaide, Australia. pp. 17-24. http://doi.acm.org/10.1145/1324892.1324896

Kray, Christian, Cheverst, Keith, Fitton, Dan, Sas, Corina, Patterson, John F., Rouncefield, Mark, Stahl, Christoph (2006): Sharing control of dispersed situated displays between nand residential users. In: Proceedings of 8th conference on Human-computer interaction with mobile devices and services , 2006, . pp. 61-68. http://doi.acm.org/10.1145/1152215.1152229

Crabtree, Andy, French, Andrew, Greenhalgh, Chris, Benford, Steve, Cheverst, Keith, Fitton, Dan, Rouncefield, Mark, Graham, Connor (2006): Developing Digital Records: Early Experiences of Record and Replay. In Computer Supported Cooperative Work, 15 (4) pp. 281-319. http://dx.doi.org/10.1007/s10606-006-9026-z

Saslis-Lagoudakis, Georgios, Cheverst, Keith, Dix, Alan J., Fitton, Dan, Rouncefield, Mark (2006): Hermes@Home: supporting awareness and intimacy between distant family members. In: Kjeldskov, Jesper, Paay, Jane (eds.) Proceedings of OZCHI06, the CHISIG Annual Conference on Human-Computer Interaction , 2006, . pp. 23-30. http://doi.acm.org/10.1145/1228175.1228183

Kray, Christian, Cheverst, Keith, Fitton, Dan, Sas, Corina, Patterson, John, Rouncefield, Mark, Stahl, Christoph (2006): Sharing control of dispersed situated displays between nand residential users. In: Nieminen, Marko, Roykkee, Mika (eds.) Proceedings of the 8th Conference on Human-Computer Interaction with Mobile Devices and Services - Mobile HCI 2006 September 12-15, 2006, Helsinki, Finland. pp. 61-68. http://doi.acm.org/10.1145/1152215.1152229

Fitton, Daniel, Cheverst, Keith, Kray, Christian, Dix, Alan J., Rouncefield, Mark, Saslis-Lagoudakis, George (2005): Rapid prototyping and user-centered design of interactive display-based systems. In IEEE Pervasive Computing, 4 (4) pp. 58-66. http://dx.doi.org/10.1109/MPRV.2005.85

Cheverst, Keith, Dix, Alan J., Fitton, Dan, Kray, Christian, Rouncefield, Mark, Saslis-Lagoudakis, George, Sheridan, Jennifer G. (2005): Exploring Mobile Phone Interaction with Situated Displays. In: Rukzio, Enrico, Häkkilä, Jonna, Spasojevic, Mirjana, Mäntyjärvi, Jani, Ravi, Nishkam (eds.) PERMID 2005 - Pervasive Mobile Interaction Devices - Mobile Devices as Pervasive User Interfaces and Interaction Devices - Workshop in conjunction with The 3rd International Conference on Pervasive Computing PERVASIVE 2005 May 11, 2005, Munich, Germany. pp. 43-47. http://www.medien.ifi.lmu.de/permid2005/pdf/KeithCheverst_Permid2005.pdf

Davies, Nigel, Cheverst, Keith, Dix, Alan J., Hesse, Andre (2005): Understanding the role of image recognition in mobile tour guides. In: Tscheligi, Manfred, Bernhaupt, Regina, Mihalic, Kristijan (eds.) Proceedings of the 7th Conference on Human-Computer Interaction with Mobile Devices and Services - Mobile HCI 2005 September 19-22, 2005, Salzburg, Austria. pp. 191-198. http://doi.acm.org/10.1145/1085777.1085809

Graham, Connor, Cheverst, Keith, Rouncefield, Mark (2005): Technology for the humdrum: trajectories, interactional needs and a care setting. In: Proceedings of OZCHI05, the CHISIG Annual Conference on Human-Computer Interaction , 2005, . pp. 1-10. http://portal.acm.org/citation.cfm?id=1108368.1108408

Graham, Connor, Cheverst, Keith, Rouncefield, Mark, Kray, Christian (2005): Going more public: situated display design in a care setting through co-realisation. In: Proceedings of the Conference on Designing for User Experiences DUX05 , 2005, . pp. 18. http://portal.acm.org/citation.cfm?id=1138235.1138256

Cheverst, Keith, Schmidt-Belz, Barbara (2005): 4th international workshop on: \"HCI in mobile guides\". In: Proceedings of 7th conference on Human-computer interaction with mobile devices and services , 2005, . pp. 359-360. http://doi.acm.org/10.1145/1085777.1085866

Davies, Nigel, Cheverst, Keith, Dix, Alan J., Hesse, Andre (2005): Understanding the role of image recognition in mobile tour guides. In: Proceedings of 7th conference on Human-computer interaction with mobile devices and services , 2005, . pp. 191-198. http://doi.acm.org/10.1145/1085777.1085809

Cheverst, Keith, Dix, Alan J., Fitton, Daniel, Kray, Chris, Rouncefield, Mark, Sas, Corina, Saslis-Lagoudakis, George, Sheridan, Jennifer G. (2005): Exploring bluetooth based mobile phone interaction with the hermes photo display. In: Proceedings of 7th conference on Human-computer interaction with mobile devices and services , 2005, . pp. 47-54. http://doi.acm.org/10.1145/1085777.1085786

Cheverst, Keith, Schmidt-Belz, Barbara (2005): 4th international workshop on: \"HCI in mobile guides. In: Tscheligi, Manfred, Bernhaupt, Regina, Mihalic, Kristijan (eds.) Proceedings of the 7th Conference on Human-Computer Interaction with Mobile Devices and Services - Mobile HCI 2005 September 19-22, 2005, Salzburg, Austria. pp. 359-360. http://doi.acm.org/10.1145/1085777.1085866

Cheverst, Keith, Dix, Alan J., Fitton, Daniel, Kray, Christian, Rouncefield, Mark, Sas, Corina, Saslis-Lagoudakis, George, Sheridan, Jennifer G. (2005): Exploring bluetooth based mobile phone interaction with the hermes photo display. In: Tscheligi, Manfred, Bernhaupt, Regina, Mihalic, Kristijan (eds.) Proceedings of the 7th Conference on Human-Computer Interaction with Mobile Devices and Services - Mobile HCI 2005 September 19-22, 2005, Salzburg, Austria. pp. 47-54. http://doi.acm.org/10.1145/1085777.1085786

Cheverst, Keith, Schmidt-Belz, Barbara (2004): 3rd International Workshop on: \"HCI in Mobile Guides. In: Brewster, Stephen A., Dunlop, Mark D. (eds.) Mobile Human-Computer Interaction - Mobile HCI 2004 - 6th International Symposium September 13-16, 2004, Glasgow, UK. pp. 521-522. http://link.springer.de/link/service/series/0558/bibs/3160/31600521.htm

Cheverst, Keith, Clarke, Karen, Fitton, Dan, Rouncefield, Mark, Crabtree, Andy, Hemmings, Terry (2003): SPAM on the menu: the practical use of remote messaging in community care. In: Proceedings of the 2003 ACM Conference on Universal Usability , 2003, . pp. 23-29. http://doi.acm.org/10.1145/957205.957210

Clarke, K., Cheverst, Keith, Dewsbury, G., Fitton, D., Hughes, J., Rouncefield, Mark, Sommerville, Ian, Hemmings, T., Rodden, Tom (2003): Cultural Probes: Eliciting Requirements for Dependable Ubiquitous Computing in the Home. In: Stephanidis, Constantine (eds.) Proceedings of the Tenth International Conference on Human-Computer Interaction June 22-27, 2003, Crete, Greece. pp. 329-333.

Cheverst, Keith, Clarke, K., Dewsbury, G., Hemmings, T., Kember, S., Rodden, Tom, Rouncefield, Mark (2003): Designing assistive technologies for medication regimes in care settings. In Universal Access in the Information Society, 2 (3) pp. 235-242. http://www.springerlink.com/openurl.asp?genre=article&issn=1615-5289&volume=2&issue=3&spage=235

Crabtree, Andy, Hemmings, Terry, Rodden, Tom, Cheverst, Keith, Clarke, Karen, Dewsbury, Guy (2003): Designing with Care: Adapting Cultural Probes to Inform Design in Sensitive Settings. In: Viller, Stephen, Wyeth, Peta (eds.) Proceedings of OzCHI 2003, New Directions in Interaction Information environments, Media and Technology November 26-28, 2003, Brisbane, Australia. pp. 4-13. http://www.cs.nott.ac.uk/~axc/work/OzCHI03.pdf

Bornträger, Christian, Cheverst, Keith, Davies, Nigel, Dix, Alan J., Friday, Adrian, Seitz, Jochen (2003): Experiments with Multi-modal Interfaces in a Context-Aware City Guide. In: Chittaro, Luca (eds.) Human-Computer Interaction with Mobile Devices and Services - 5th International Symposium - Mobile HCI 2003 September 8-11, 2003, Udine, Italy. pp. 116-130. http://link.springer.de/link/service/series/0558/bibs/2795/27950116.htm

Fitton, Dan, Cheverst, Keith (2003): Experiences Managing and Maintaining a Collection of Interactive Office Door Displays. In: Aarts, Emile H. L., Collier, René, Loenen, Evert van, Ruyter, Boris E. R. de (eds.) EUSAI 2003 - Ambient Intelligence - First European Symposium November 3-4, 2003, Veldhoven, The Netherlands. pp. 394-409. http://link.springer.de/link/service/series/0558/bibs/2875/28750394.htm

Cheverst, Keith, Dix, Alan J., Fitton, Dan, Friday, Adrian, Rouncefield, Mark (2003): Exploring the Utility of Remote Messaging and Situated Office Door Displays. In: Chittaro, Luca (eds.) Human-Computer Interaction with Mobile Devices and Services - 5th International Symposium - Mobile HCI 2003 September 8-11, 2003, Udine, Italy. pp. 336-341. http://link.springer.de/link/service/series/0558/bibs/2795/27950336.htm

Cheverst, Keith, Mitchell, Keith, Davies, Nigel (2002): Exploring Context-aware Information Push. In Personal and Ubiquitous Computing, 6 (4) pp. 276-281. http://springerlink.metapress.com/openurl.asp?genre=article&issn=1617-4917&volume=6&issue=4&spage=276

Cheverst, Keith, Mitchell, Keith, Davies, Nigel (2002): The role of adaptive hypermedia in a context-aware tourist GUIDE. In Communications of the ACM, 45 (5) pp. 47-51. http://doi.acm.org/10.1145/506218.506244

Cheverst, Keith, Davies, Nigel, Mitchell, Keith, Efstratiou, Christos (2001): Using Context as a Crystal Ball: Rewards and Pitfalls. In Personal and Ubiquitous Computing, 5 (1) pp. 8-11. http://springerlink.metapress.com/openurl.asp?genre=article&issn=1617-4917&volume=5&issue=1&spage=8

Cheverst, Keith, Smith, Gareth, Mitchell, Keith, Friday, Adrian, Davies, Nigel (2001): The role of shared context in supporting cooperation between city visitors. In Computers & Graphics, 25 (4) pp. 555-562. http://dx.doi.org/10.1016/S0097-8493(01)00083-8

Davies, Nigel, Cheverst, Keith, Mitchell, Keith, Efrat, Alon (2001): Using and Determining Location in a Context-Sensitive Tour Guide. In IEEE Computer, 34 (8) pp. 35-41. http://csdl.computer.org/computer/co2001/r8035abs.htm

Cheverst, Keith, Davies, Nigel, Mitchell, Keith, Friday, Adrian, Efstratiou, Christos (2000): Developing a Context-Aware Electronic Tourist Guide: Some Issues and Experiences. In: Turner, Thea, Szwillus, Gerd, Czerwinski, Mary, Peterno, Fabio, Pemberton, Steven (eds.) Proceedings of the ACM CHI 2000 Human Factors in Computing Systems Conference April 1-6, 2000, The Hague, The Netherlands. pp. 17-24. http://www.acm.org/pubs/articles/proceedings/chi/332040/p17-cheverst/p17-cheverst.pdf

Cheverst, Keith, Blair, Gordon S., Davies, Nigel, Friday, Adrian (1999): The Support of Mobile-Awareness in Collaborative Groupware. In Personal and Ubiquitous Computing, 3 (1) pp. . http://

Cheverst, Keith, Mitchell, Keith, Davies, Nigel (1999): Design of an object model for a context sensitive tourist GUIDE. In Computers & Graphics, 23 (6) pp. 883-891. http://dx.doi.org/10.1016/S0097-8493(99)00119-3

Cheverst, Keith, Davies, Nigel, Mitchell, Keith, Friday, Adrian (1999): The Role of Connectivity in Supporting Context-Sensitive Applications. In: Gellersen, Hans-Werner (eds.) Handheld and Ubiquitous Computing - First International Symposium - HUC99 September 27-29, 1999, Karlsruhe, Germany. pp. 193-207. http://link.springer.de/link/service/series/0558/bibs/1707/17070193.htm

Cheverst, Keith

14.10 Commentary by Keith Cheverst

Context-aware behaviour is standard on modern smart phones and for me it’s a little strange (and encouraging) to think that a short ten or so years ago we were still writing research papers on the subject. Albrecht has been an eminent figure on context-awareness during this time and this chapter effortlessly captures both the depth and breadth of the subject matter in a text that is refreshingly easy to digest.

I sneakily used a draft of the chapter as the reading material for a master’s level HCI class recently and it worked very well indeed. The chapter provides an excellent historical perspective on the subject matter including the key motivating forces behind context-awareness, namely mobile and ubiquitous computing.  It was good to be reminded of the early examples introduced by Bill Schilit such as the listing of printers according to their proximity - something I would still like to see. But Albrecht’s own examples presented in the chapter helped to both illustrate key concepts and stimulate much interesting design discussion. 

One important key concept that Albrecht addresses very clearly and which students can struggle with is the hierarchical model by which raw sensor data can be translated into higher level context triggers. While working through the detailed worked example in this section, I found myself musing on how familiar my current class of students are with sensors, such as accelerometers and gyroscopes, compared to a class of just a few years ago.

In addition to its technical/architectural treatment of context-awareness the chapter is also rich in its coverage of ‘implications for HCI’. As Albrecht argues clearly, context-awareness provides a powerful tool for the interaction designer. When used well it enables the design of systems that can help ‘take the load off’ but when used poorly can lead to the production of systems that prove burdensome to say the least.

One of the key challenges faced by any designer wishing to implement context-aware behaviour is that of maintaining predictability and I found myself nodding in agreement while reading Albrecht’s discussion of what he terms ‘the awareness mismatch’ which he succinctly models using the User-Context Perception Model (UCPM).

Another challenging issue for the designer is how best to maintain appropriate levels of control for the user, to keep the user in the loop so to speak. This is especially important for those context-aware systems that implement proactive/adaptive behaviour. As Albrecht states “...a central challenge is to provide means in the user interface to correct wrong choices made by the system, and in a way where the user feels in control”. I am reminded very much of an annoying ‘habit’ exhibited by my current ‘smart’ phone. I get frustrated when it insists on pausing music playback whenever I place the thing face down. I often place it face down because the speaker is on the back of the phone and so by placing it face down (i.e. ‘speaker up’) I achieve the most volume. At times like this I wish there was some kind of ‘hold’ button that would cause the phone to enter a mode whereby all context triggers based on physical actions would be disabled (or rather banished). However, for whatever reason (patent?) the phone doesn’t have one and so I don’t feel as if I have this control (maybe there is such a feature described somewhere in the manual...). Next to the hold button I would have a ‘show me the rule explaining why you just did that’ button. As Albrecht states: “...if the user is puzzled about an automatic adaptation done by the system, we should however provide means to inquire into the problem for the user”. This reminds me of some of the research by Judy Kay on scrutability (Kay, 1998) within the user modelling domain. At Lancaster we explored this issue with the development of a system that enabled the user to scrutinise (and possibly override) rules inferred by a proactive context-aware system (supporting office environment control) based on context history (Cheverst, 2005). Supporting such user inquiry while maintaining simplicity is clearly hard (and not a simple matter of adding more buttons...). But unchecked the feeling of ‘why is IT doing that and how can I stop it!?” can start to feel like a war of attrition with a contrary being. Indeed, when summarising context-aware behaviour, Albrecht states “The basic idea is to give computers perceptual qualities (“eyes and ears”) in order to make them recognize the situations in which users interact with information systems”.  So my phone needs to be smart enough to recognise and discern between the situation where I place it face down because I want greater volume and the situation where I quickly place the phone face down because the phone has started to ring during a meeting and I want it to go silent immediately.  Albrecht provides a wonderfully clear worked example to demonstrate how one can procedurally think about the appropriate matching of sensory-based inputs to certain situations, i.e. “to assess and define what the relevant and characterizing features are”. So hopefully future designers of context-aware behaviour will take the opportunity to read Albrecht’s chapter and produce the kind of smart behaviours that assist rather than hinder and befriend rather than estrange.

References

  • Kay, J.: A scrutable user modelling shell for user-adapted interaction, PhD Thesis, Basser Department of Computer Science, University of Sydney, Australia (1998)
  • Cheverst, K, Byun, H, Fitton, D, Sas, C, Kray, C & Villar, N, 'Exploring Issues of User Model Transparency and Proactive Behaviour in an Office Environment Control System', Special Issue of UMUAI (User Modelling and User-Adapted Interaction) on User Modeling in Ubiquitous Computing, pp. 235-273. (2005)