Human on-line response to visual and motor target expansion
The components of graphical user interfaces can be made to dynamically expand as the cursor approaches, providing visually appealing effects. Expansion can be implemented in a variety of ways: in some cases the targets expand visually while maintaining a constant smaller motor-space for selection; and in others both the visual and motor-spaces of the objects are enlarged. Previous research by McGuffin & Balakrishnan , and confirmed by Zhai et al. , has shown that enlarged motor-space expansion improves acquisition performance. It remains unclear, however, what proportion of the performance improvement is due to the enlarged motor-space, and what to the confirmation of the over-target state provided by visual expansion. We report on two experiments which indicate that for small targets, visual expansion in unaltered motor-space results in similar performance gains to enlarged motor-spaces. These experiments are based on tasks where users are unable to anticipate the behaviour of the targets. Implications for commercial use of visual expansion in unaltered motor-space are discussed.