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Interactive Poster: User-Centered Design and Evaluation

CHI

changing the world, changing ourselves

Evaluating pattern languages in participatory design Andy Dearden Computing Research Centre Sheffield Hallam University Sheffield S1 1WB, UK +44 114 225 2916 [email protected]

Janet Finlay, Liz Allgar School of Computing, Leeds Metropolitan University, The Grange, Beckett Park, Leeds, LS6 3QS, UK +44 113 283 2600 {j.finlay, e.allgar}@lmu.ac.uk

Barbara McManus Department of Computing University of Central Lancashire, Preston PR1 2HE, UK +44 1772 893288 [email protected]

ABSTRACT

which reflects the same emphasis:

We present an evaluation of pattern languages as tools for participatory design, based on three criteria, derived from the work of Christopher Alexander: empowering users, generative design and life-enhancing outcomes. Our results suggest that pattern languages can be used to enable users to participate in design, but that the role of facilitator and the form and physical presentation of the pattern language are factors in success.

“The goals of an HCI pattern language are to share successful HCI design solutions among HCI professionals…” (our emphasis, as quoted in [4, p39])

Keywords

Pattern languages, participatory design INTRODUCTION

In recent years the Human-Computer Interaction (HCI) community has witnessed a growing interest in the use of ‘design patterns’ and ‘pattern languages’. Much of this has been inspired by the perceived success of software engineers in applying design patterns. In this paper, we present three criteria for effective pattern languages, developed from Alexander’s original work [1,2,3], and discuss our preliminary experiences in evaluating pattern languages against these criteria. PATTERNS AND PATTERN LANGUAGES

Alexander described a pattern as “… a three part rule, which expresses a relation between a certain context, a problem and a solution.” [1, p247]. The patterns in [2] are organized into a hierarchy (technically a partial order) with high-level patterns addressing problems such as the size and distributions of cities, moving down through patterns about civic arrangements, to patterns for individual buildings and individual rooms. Each pattern includes links to its parents and children within the hierarchy. By traversing the hierarchy, the user of the language is supported in ‘generating’ complete designs. For software engineers, the main purpose of patterns has been to share successful solutions within the profession [5]. In HCI, a definition was generated at Interact ’99,

Copyright is held by the author/owner(s). CHI 2002, April 20-25, 2002, Minneapolis, Minnesota, USA. ACM 1-58113-454-1/02/0004.

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THREE CRITERIA FOR EVALUATING PATTERNS Empowering Users

In contrast to the above, Alexander intended pattern languages to be a means of sharing design knowledge with users of buildings, as part of a participatory process [3, cf. 6]. Indeed, users should be involved in critiquing and evolving pattern languages [1]. These aspects of pattern languages have not been considered in software engineering, and have received little attention in HCI. Our first criterion, therefore, examines how pattern languages can be used and developed in participation with users. Generative design

Alexander’s intention was that a pattern language should allow users to generate complete designs. He explicitly relates pattern languages to Chomsky’s notion of generative grammar [1, p187]. This aspect of his work has been discussed in HCI [4], but has not been convincingly demonstrated. Our second criterion examines whether this goal can be achieved in HCI. Life-enhancing outcomes

Throughout his work, Alexander talks of his aim to achieve ‘the Quality without a Name’ [1,2,3]. His stated aim is that people experiencing buildings developed using pattern languages should recognise this quality. Their lives should be enhanced by the experience. Our third criterion examines user responses to the products of design using pattern languages. INVESTIGATING PATTERN LANGUAGES

A pattern language was developed for a restricted type of website, namely airline and rail-travel sites. The language, consisting of 23 patterns, was derived from published HCI patterns, in particular [4, 7]. The patterns were formatted in a consistent style similar to Alexander’s [2]. Design exercises were conducted with 6 users ranging in experience from a retired non-web-user to a trainee web designer. Two users were given the pattern language to read for 1 hour in advance of their design session. Two were introduced to the language at the beginning of the

minneapolis, minnesota, usa • 20-25 april 2002

session. Two were introduced to individual patterns or groups of patterns as the design session progressed. In all cases, the users were asked to develop a paper prototype of a travel website using the pattern language. All the users were told that following the patterns was not compulsory, and that the illustrations shown were examples only and not definitive ‘best practice’. The sessions lasted between 1 and 2 hours, and were videotaped. All participants were interviewed following the task. Below, we outline our initial observations in relation to our three criteria. Empowering users

All the sessions resulted in feasible design sketches, at varying levels of detail. The process enabled novice users with no experience of web design to participate in the design of a website. More experienced designers indicated that the language had supported their design activity, in one case highlighting elements that would otherwise have been missed. In addition, with all users, the language became a vehicle for discussion between the facilitator and the userdesigner. All users challenged the patterns, in some way, including rejecting the recommended solution within an individual pattern; proposing alternative solutions for a particular problem; questioning assumptions about functionality embedded within the pattern; and raising issues that the language did not address. On the other hand, two of the novice users seemed to treat the patterns as ‘correct’ answers, rejecting their own ideas when they were in conflict with the pattern. Generative process

Interactive Poster: User-Centered Design and Evaluation

Finally, the form of the pattern language as a physical artefact is important. Our patterns were presented as unbound single A4 sheets. We observed users browsing the set, searching the set for a specific remembered pattern, example or diagram, and organising the set spatially. The spatial organisation reflected either a sense of ‘ownership’ and an attempt to group related patterns. The physical form of the pattern language must facilitate these activities. Life-enhancing outcomes

Our results to date are insufficient to make claims about the quality of the products from participatory use of pattern languages. The designs that our users produced were paperbased sketches developed in a short time and some appear to be closely derivative from the examples used to illustrate the patterns. We have noticed that our process and language does not deal with the possibly divergent interests of different stakeholders, e.g. users and airline owners. We are therefore reviewing the language and conducting further studies to extend the process to develop complete artefacts (in this and other domains) which can then be evaluated. CONCLUSIONS

We have demonstrated that even a limited pattern language can have benefit in empowering users to participate in design processes. We need to refine the language and the process to deepen our understanding of the empowering and generative potential of pattern languages in participatory design, and to test whether this type of process can generate life-enhancing outcomes.

All users produced partial designs that were internally coherent, with both layout and navigational elements. Our analysis of the data suggests three issues that may be significant in developing an effective, generative process.

ACKNOWLEDGMENTS

Firstly, the form of facilitation is important. During the exercises there are transitions in the locus of control of the drawing process, of the sequencing of design questions, and of the handling of the patterns. These transitions tend towards the users gradually taking more control, raising the question of how such a transition can be effectively enabled.

REFERENCES

Secondly, the form of the patterns is significant. Some users focused exclusively on the illustrated examples. Others used the examples together with the emboldened problem and solution texts. No users made reference to the using the supporting text, although two users read through the patterns in full in advance of the session, and one spent the first 23 minutes of the session reading the patterns. This suggests that the choice of examples is critical. One of our users commented that he would begin by considering a range of examples by visiting multiple websites. Certainly, a variety of examples is recommended. It is also debatable whether the full pattern form is appropriate for use in participatory design, or whether a cut down ‘view’ of the pattern showing the problem, examples and solution would be more useful.

We acknowledge the support of our respective institutions, the time and effort of the participants in our investigations, and Kay Plowman for originating the pattern language. 1. Alexander, C. The Timeless Way of Building. Oxford University Press, NY, 1979. 2. Alexander, C., Ishikawa, S., Silverstein, M.,Jacobson, M., Fiksdahl-King, I., and Angel, S. A Pattern Language. Oxford University Press, NY, 1977. 3. Alexander, C., Davis, H., Martinez, J., & Corner, D. The Production of Houses. Oxford University Press, NY, 1985. 4. Borchers, J. A Pattern Approach to Interaction Design. John Wiley and Sons, Chichester, UK, 2001. 5. Gamma, E., Helm, R., Johnson, R., and Vlissides, J. Design Patterns: Elements of Reusable Object-Oriented Software. Addison-Wesley, Reading, MA, 1995. 6. Greenbaum, J. & Kyng, M., (Eds.) 1989. Design at Work. Laurence Erlbaum Associates: Hillsdale, NJ. 7. Tidwell, J. Common Ground: A Pattern Language for Human-Computer Interface Design. Available at http://www.mit.edu/~jtidwell/common_ground_onefile.html

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