There are many people who find the standard computer input devices-the keyb
oard and mouse-difficult to use due to a motor disability. A number of keyb
oard and mouse configuration options designed to overcome physical difficul
ties exist. However, formal empirical evaluation of such facilities is rare
. There is, in fact, little data available on the precise nature of physica
l difficulties with input devices. Hence, it is difficult to gauge the adeq
uacy of existing access provision. This paper presents an empirical study o
f the keyboard and mouse errors encountered in a sample of 20 computer user
s with motor disabilities, and six without disabilities. Six important clas
ses of keyboard difficulty are identified, involving significant correction
time for participants with disabilities. Difficulties with all aspects of
mouse usage were observed, particularly pointing and dragging. Many of the
difficulties observed would be amenable to automatic detection. It is hoped
that these results will help to inform the development of more accessible
software and hardware. (C) 1999 Academic Press.