ABSTRACT
Target expansion, increasing target size according to cursor movement, is a novel scheme to enhance the speed and accuracy of target selection tasks. This study examines the effects of four age groups and eight target expansion methods on target acquisition tasks with multiple targets. Thirty two subjects performed the combinations of four expansion areas and two expansion techniques. Older users took longer to acquire targets than did younger users. The task completion time was shortest when expanding no and one-icon areas with the occlusion tcchnique. The error rate was lowest whcn expanding group area with thc push technique. All age groups were most satisfied with the method of expanding onc-icon area with the occlusion tcchnique. We suggest two alternative guidclines in designing target expansion methods for target acquisition tasks using a mousc. In a OUI in which targets expand, it is desirablc to expand only the target to which the cursor points. When designing a our to simultaneously expand a spccific group, it is desirable to push surrounding groups aside. It is expected that usability of related software can be improved when using these target expansion schemes in practical our designs.
Keywords: Target Expansion Scheme, Target Acquisition, Graphical User Interface
