CHI 97 Electronic Publications: Workshops
Testing for Power Usability
Keith S. Karn, Ph.D.
Xerox Corporation, Industrial Design / Human Interface Department
1350 Jefferson Road, Mail Stop: Henr0801-10C
Rochester, NY 14623 USA
+1-716-427-4549
keith_karn@mc.xerox.com
Thomas J. Perry
Xerox Corporation, Industrial Design / Human Interface Department
1350 Jefferson Road, Mail Stop: Henr0801-10C
Rochester, NY 14623 USA
+1-716-427-1708
thomas_j_perry@mc.xerox.com
Marc J. Krolczyk
Xerox Corporation, Industrial Design / Human Interface Department
1350 Jefferson Road, Mail Stop: Henr0801-10C
Rochester, NY 14623 USA
+1-716-427-1879
marc_krolczyk@mc.xerox.com
Keywords
power user, usability, testing, evaluation, production systems
© 1997 Copyright on this material is held by the authors.
INTRODUCTION
Usability studies are usually conducted in a compressed time scale
(measured in hours) compared with a user's eventual experience with a
product (often measured in years). For this reason, typical usability
evaluations focus on success during initial interactions with a
product (see for example Dumas & Redish, 1994 and Nielsen &
Mack, 1994). Success on initial use is often driven by familiarity.
Are what we call intuitive user interfaces really just familiar
user interfaces? This familiarity effect can often swamp the
usability differences between design alternatives. If usability
evaluations continue to emphasize initial success with a product, we
may inhibit innovation in user interface design. There is a tension
between initial usability (measured by success at first encounter) and
efficiency of skilled performance. Initial learning of a product's
user interface often results in quite rapid increases in efficiency of
use. A narrow focus on initial usability elevates learnability above
efficiency once up the learning curve. While this approach is
appropriate for some products targeted primarily for casual /
occasional users, it fails to capture the usability issues associated
with power users (those with significant experience, training, or a
professional orientation to their interaction with the product).
GOALS
The goals of this workshop are to exchange and develop techniques to
address three issues:
- Evaluating products that introduce new features to an established,
highly-experienced / power user population.
- Evaluating usability of entirely new technologies (innovative /
novel products that may include a new and unfamiliar user interface).
- Simulating power use of a product when experienced users are not
available - either before power users exist or when they cannot
participate. The emphasis is on how we should train users prior to
participation.
RELEVANCE TO COMPUTER-HUMAN INTERACTION
While the topic outlined may be of interest to developers and
applied researchers for many types of products, it is particularly
relevant to the computer-human interaction community at this time.
Currently, and even more so as we look into the future, we notice an
increase in the frequency with which people find themselves immersed
in use of computer products and likewise, an increase in the duration
of that immersion at work, in school, and at play. As mentioned in
the introduction, initial learning of a product's user interface often
results in great increases in efficiency of use whether it be with a
computer game or a business software application. Thus, traditional
usability evaluation techniques, with their emphasis on initial use of
a product may fail to capture the usability issues that affect users
the most - those that appear after they have established proficiency
with the product. The time spent with a product once up on a learning
plateau typically greatly exceeds the time on the steeper part of the
learning curve. We do not question the importance of testing a
product's learnability , (see Usability Sciences Corporation,
1994) but feel that the computer-human interaction community has a
responsibility to concern ourselves with usability of products
throughout their life-cycle. Initial interactions with a product may
affect the purchase decision, but usability over the longer term may
determine whether a customer will recommend the product to others and
become a repeat customer.
REFERENCES
- Dumas, J., Redish, J. (1994) A Practical Guide to Usability
Testing. Norwood, NJ: Ablex.
- Neilson, J., Mack, R. (1994) Usability Inspection Methods.
NY: John Wiley & Son.
- Usability Sciences Corporation (1994) Windows 3.1 and Windows 95
Quantification of Learning Time and Productivity. (available from
http://www.microsoft.com/windows/product/usability.htm)
CHI 97 Electronic Publications: Workshops
