• Victoria Bellotti , Ann Blandford , David Duke , Allan MacLean , Jon May , Laurence Nigay
Human Computer Interaction, 1996, Vol. 11, pp 357-432.
Certain innovative design projects raise difficult user-interface problems which are not easily amenable to
designers’ intuition or rapid prototyping, due to their novelty, conceptual complexity and the difficulty of
conducting appropriate user studies. Interpersonal access control in computer mediated communication
systems is just such a problem. We describe a collection of systematic analyses of a system prototype which
inherited its control mechanism from two pre-existing systems. We demonstrate that the collective use of
system and user modelling techniques provides insight into this complex design problem and enables us to
examine the implications of design decisions for users and implementation. The analyses identify a number of
weaknesses in the prototype, and are used to propose ways of making substantive refinements to improve its
simplicity and appropriateness for the tasks of altering one’s accessibility and distinguishing between who can
make what kinds of connections. We conclude with a discussion of some critical issues which are relevant for
computer-mediated communications systems in general, and reflect on the process of applying formal HCI
techniques in informal, exploratory design contexts.
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