Alexander[1,2], in developing his architectural patterns
visited ``places that worked'' to
gather the characteristics of these places for later analysis. While it would
be possible to examine interactive systems in this same way, it was our opinion
that
the literature already contains patterns and nascent patterns in the form of
the many principles and guidelines that have been articulated.
These principles and guidelines endeavor to abstract the characteristics of
``interfaces that work.''
Design principles for interactive systems abound in the literature.
It was our initial
belief that many of the operational principles in the literature would be more concrete
and particular than the patterns. Similarly, we felt that the
more conceptual principles might
be very close to patterns, subsuming other principles.
We sought patterns in line with what Thimbleby[18, p 202,] has
referred to as "generative user engineering principles." That is, a pattern
should be easy to instantiate in a given situations and it should
provide specific
guidance about what should be done. Our contention was that
a pattern such as ``provide for ordered information" would be more easily
understood and used than an abstract high level principle such as
Norman's ``reduce the gulf of
evaluation''[12].