  The main purpose of this study was to investigate the nature of preferences
and their relation to the objective measures in simple direct manipulation
tasks involving both the cognitive process as well as the visually guided
pointing activities. The conducted experiment was concerned with the graphical
structures resembling toolbars widely used in graphical interfaces. The
influence of the graphical panel location, panel configuration as well as the
target size on the user task efficiency and subjects' preferences were
examined. The participants were requested to express their attitudes towards
the tested panels before and after the efficiency examination. This subjective
evaluation was carried out within the framework of Analytic Hierarchy Process
(AHP; Saaty, 1977; 1980). The subjective results that were obtained showed
significant differences in the subjects' preferences towards examined panels
before and after completing the tasks. It seems that the users are able to
comparatively quickly change their minds after gaining some experience with the
investigated stimuli. Additionally, the applied cluster analysis revealed that
the subjects were not homogenous in their opinions, and they formed groups
having similar preference structures.
