We first began looking at pointing devices and human performance in 1990
when the senior author, Sarah Douglas, was asked to evaluate the human
performance ofa rather novel device: a finger-controlled isometric
joystick placed under a key on the keyboard. Since 1990 we have been
involved in the development and evaluation ofother isometric joysticks,
a foot-controlled mouse, a trackball, and a wearable computer with head-
mounted display. We unabashedly believe that design and evaluation of
pointing devices should evolve from a broad spectrum of values which
place the human being at the center. These values include performance
iss- ues such as pointing-time and errors, physical issues such as
comfort and health, and contextual issues such as task usabilityand user
acceptance. This book chronicles this six-year history of our
relationship as teacher (Douglas) and student (Mithal), as we moved from
more traditional evalu- ation using Fitts' law as the paradigm, to
understanding the basic research literature on psychomotor behavior.
During that process we became pro- foundly aware that many designers of
pointing devices fail to understand the constraints of human
performance, and often do not even consider experimental evaluation
critical to usability decisions before marketing a device. We also
became aware ofthe fact that, contraryto popularbeliefin the
human-computer interaction community, the problem of predicting pointing
device performance has not been solved by Fitts' law. Similarly, our
expectations were biased by the cognitive revolution of the past 15
years with the beliefpointing device research was 'low-level' and
uninter- esting.
