  The main objective of this paper was to investigate the effects of a computer
screen interface design and its related geometrical characteristics of 36
graphical objects on a user's task efficiency. A total of 490 subjects took
part in laboratory experiments that focused on the direct manipulation of a
visual dialogue between a user and a computer. The subjects were asked to
select an object from among a group of items randomly placed on the computer
screen that were visible exclusively during the visual search process. A model
expressing the mean object acquisition time as a function of graphical object
size and the configuration was developed and statistically validated. The model
showed an influence of geometrical design characteristics of the graphical
objects (icons) and their groupings (icon structures) on the observed task
efficiency. The reported results can be used at those stages of a software
lifecycle that concentrate on prototyping, designing, and implementing
graphical solutions for the efficient graphical user-computer interface.
