ABSTRACT
The apparently endless options for the design of human-computer interfaces are composed from only a very few sensory-motor and cognitive operations performable by the user. These include: the perceptual operations of visual search and reading and the motor operations of typing on the keyboard and reaching with a hand to a target. This chapter focuses on one issue within this realm—the implications for design of the reaching-to-target operations. It considers the mouse, a rate-controlled isometric joystick, step keys, and text keys. The purpose of the experiment was to compare the relative merits for text-selection of a number of devices. To make the comparison meaningful a number of factors had to be controlled, including individual differences; learning and asymmetrical transfer of training between devices; movement direction; target size, target distance, users' motivation, and the possibility of important extraneous variables.
