WJ Clancey — Visualizing Practical Knowledge
learned on the job. Necessarily, this changes the tools we provide. For example, today we
are implementing new electronic procedure manuals on the space shuttle. For Mars, we
will need tools by which astronauts can write and revise their own plans.
The field of software engineering today is something like the building crafts before
architecture developed as a discipline. Methods are locally adapted and the systems are
incrementally modified to fit the needs of a particular user population. But too often
software does not fit the context in which it is to be used. Invariably, discussions of
computer system “architectures” view workplaces as just networks, communication
devices, and workstations. Engineers know how to integrate objects and processes, but
not how to relate people and their practices in new ways. Designing work systems
requires something like architecture, an understanding of how people actually use tools,
their activities, and how new devices would facilitate human interactions.
One effort to develop an architecture for computer system design is called “human-
centered computing.” This is a research effort, starting with the scientific study of people
and machines. What can people do today that no computer can do (e.g., conceptualize
and relate ideas in different modalities)? What can computers do more accurately than
people (e.g., filter and sort data based on defined criteria)? How shall we put these two
capabilities together to create a synergistic system?
From the perspective of practical knowledge, we want to help make groups more
adaptable. This means facilitating learning, of which one important method is to facilitate
conversations between people. In the same way, rather than talking about “usability” of
systems alone, we design for learnability.
The key ideas in human-centered design are: adopting a total systems perspective
(considering organizations, procedures, technologies, and facilities together) and
designing in the context of use. Ethnographic observational techniques are especially
useful—participating with people in their own work environment to better understand
their problems, opportunities, and aspirations. Ethnography is the written study of human
culture. This observational methodology reveals the presence and effects of human
interaction, conversation, identity, genre, and rhythm in everyday human life.
In summary, human-centered computing is a multidisciplinary design methodology,
incorporating a variety of goals—making usable systems, augmenting cognition, and
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