  Pointing devices that reside on the keyboard can reduce the overall time
needed to perform mixed pointing and typing tasks, since the hand of the user
does not have to reach for the pointing device. However, previous
implementations of this kind of device have a higher movement time compared to
the mouse and trackpad due to large error rate, low speed and spatial
resolution. In this paper we introduce Keyboard Surface Interaction (KSI), an
interaction approach that turns the surface of a keyboard into an interaction
surface and allows users to rest their hands on the keyboard at all times to
minimize fatigue. We developed a proof-of-concept implementation, Fingers,
which we optimized over a series of studies. Finally, we evaluated Fingers
against the mouse and trackpad in a user study with 25 participants on a Fitts
law test style, mixed typing and pointing task. Results showed that for users
with more exposure to KSI, our KSI device had better performance (reduced
movement and homing time) and reduced discomfort compared to the trackpad. When
compared to the mouse, KSI had reduced homing time and reduced discomfort, but
increased movement time. This interaction approach is not only a new way to
capitalize on the space on top of the keyboard, but also a call to innovate and
think beyond the touchscreen, touchpad, and mouse as our main pointing devices.
The results of our studies serve as a specification for future KSI devices.
