ABSTRACT
What’s An Input Device Anyway? . . . . . . . . . . . . . . . . . 138
Understanding Input Technologies . . . . . . . . . . . . . . . 138
Input Device Properties . . . . . . . . . . . . . . . . . . . . . . . . . 138
Property sensed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Number of dimensions . . . . . . . . . . . . . . . . . . . . . . . 138
Indirect versus direct . . . . . . . . . . . . . . . . . . . . . . . . 138
Device acquisition time . . . . . . . . . . . . . . . . . . . . . . 138
Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Other metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
A Brief Tour of Pointing Devices . . . . . . . . . . . . . . . . . . 139
Mice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Trackballs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Isometric joysticks . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Isotonic joysticks . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Indirect tablets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Touchpads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Touchscreens and pen-operated devices . . . . . . . . . 139
Input Device States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
What’s an Input Device For? The Composition
of User Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Elemental Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Compound Tasks and Chunking . . . . . . . . . . . . . . . . . . . 141
Evaluation and Analysis of Input Devices . . . . . . . . . . 141
Fitts’ Law and Hick’s Law . . . . . . . . . . . . . . . . . . . . . . . . . 142
The Steering Law and Minimum Jerk Law . . . . . . . . . . . . 142
The Keystroke-Level Model (KLM) and
GOMS Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Transfer Functions: How to Transform
an Input Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Self-centering devices . . . . . . . . . . . . . . . . . . . . . . . . 143
Motion-sensing devices . . . . . . . . . . . . . . . . . . . . . . . 143
Absolute devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Feedback: What Happens in Response to an Input? . . 143
Proprioceptive and Kinesthetic Feedback . . . . . . . . . . . . 143
Kinesthetic Correspondence . . . . . . . . . . . . . . . . . . . . . . 143
Snapping Behaviors and Active Haptic Feedback . . . . . . 144
Keyboards and Text Entry . . . . . . . . . . . . . . . . . . . . . . . 144
Procedural Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Mobile Text Entry, Character Recognition,
and Handwriting Recognition . . . . . . . . . . . . . . . . . . . . . 144
Modalities of Interaction . . . . . . . . . . . . . . . . . . . . . . . . 145
Speech and Multimodal Input . . . . . . . . . . . . . . . . . . . . . 145
Bimanual Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Pen and Gesture Input . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Whole Hand Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Background Sensing Techniques . . . . . . . . . . . . . . . . . . . 146
Multitouch Tables and Screens . . . . . . . . . . . . . . . . . . . . . 147
A Society of Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Current and Future Trends for Input . . . . . . . . . . . . . 147
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Input devices sense physical properties of people, places, or things. Yet any treatment of input devices without regard to the corresponding visual feedback is like trying to use a pen without paper. Small-screen devices with integrated sensors underscore the indivisibility of input and output. This chapter treats input technologies at the level of interaction techniques, which provide a way for users to accomplish tasks by combining input with appropriate feedback. An interaction designer must consider (a) the physical sensor, (b) the feedback presented to the user, (c) the ergonomic and industrial design of the device, and (d) the interplay between all of the interaction techniques supported by a system.
