Proceedings: GI 2006

Human on-line response to visual and motor target expansion

Andy Cockburn, Philip Brock

Proceedings of Graphics Interface 2006: Québec, Québec, Canada, 7-9 June 2006, 81-87

  • BibTex

    author = {Cockburn, Andy and Brock, Philip},
    title = {Human on-line response to visual and motor target expansion},
    booktitle = {Proceedings of Graphics Interface 2006},
    series = {GI 2006},
    year = {2006},
    issn = {0713-5424},
    isbn = {1-56881-308-2},
    location = {Qu{\'e}bec, Qu{\'e}bec, Canada},
    pages = {81--87},
    numpages = {7},
    publisher = {Canadian Human-Computer Communications Society},
    address = {Toronto, Ontario, Canada},


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 [15], and confirmed by Zhai et al. [19], 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.