Consistency vs. Multiplicity in Interface Design:
Limitations of Single Interface Metaphors
Liang-Yi Lin
James A. Levin
University of Illinois at Urbana-Champaign
Champaign, IL 61820
Abstract
Many prescriptive interface design guides stress the importance of consistency
in interface design, so that novice users are not confused and can learn new
applications more quickly. While agreeing that consistency is generally a good
thing, this paper presents research that shows some of the limitations of
consistency. The first experiment points to the task specific value of single
interface models. Subjects using any one of three interface models (book, note
card, map) did well on certain tasks and more poorly on others. There was a
strong interaction between the type of interface and the type of task the
subjects were given. The second and third experiments explored the acquisition
of skill in using multiple interfaces vs. a single interface. Subjects
learning a single interface initially outperformed the subjects learning three
interfaces. However, the consistent interface subjects' performance topped
out, and there was a cross-over point after extended use of the interfaces,
after which the multiple-interface subjects outperformed the single-interface
subjects. They showed more cognitive flexibility, choosing the interface that
was appropriate for each task they were faced with. Consistency produced a
fast learning curve, but also limited the level of expertise that users
achieved.
Topic areas: interface design, user models, design principles
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