Abstract
Available Versions
Citation
Abstract
Prior work has highlighted the challenges faced by people with
motor impairments when trying to acquire on-screen targets using
a mouse or trackball. Two reasons for this are the difficulty of
positioning the mouse cursor within a confined area, and the
challenge of accurately executing a click. We hypothesize that
both of these difficulties with area pointing may be alleviated in a
different target acquisition paradigm called "goal crossing." In
goal crossing, users do not acquire a confined area, but instead
pass over a target line. Although goal crossing has been studied
for able-bodied users, its suitability for people with motor
impairments is unknown. We present a study of 16 people, 8 of
whom had motor impairments, using mice and trackballs to do
area pointing and goal crossing. Our results indicate that Fitts'
law models both techniques for both user groups. Furthermore,
although throughput for able-bodied users was higher for area
pointing than for goal crossing (4.72 vs. 3.61 bits/s), the opposite
was true for users with motor impairments (2.34 vs. 2.88 bits/s),
suggesting that goal crossing may be viable for them. However,
error rates were higher for goal crossing than for area pointing
under a strict definition of crossing errors (6.23% vs. 1.94%).
Subjective results indicate a preference for goal crossing among
motor-impaired users. This work provides the empirical
foundation from which to pursue the design of crossing-based
interfaces as accessible alternatives to pointing-based interfaces.
PDF