Surfpad: riding towards targets on a squeeze film effect

Numerous techniques have been proposed that attempt to beat Fitts' law, i.e. to make virtual pointing easier than it is in the physical world [1]. Most of these techniques attempt to decrease target distance, to increase target width, or both. Most of them are also inherently target-aware [2]: they take advantage of some knowledge about the size and position of the targets and sometimes modify them. In cases where pointing involves the indirect control of a visual cursor, some techniques operate by dynamically adapting the control-display gain. Other techniques supplement the visual display with auditory or haptic feedback. Yet despite their demonstrated efficiency in simple configurations, most target-aware pointing techniques are difficult to use in practice. One of the key problems that affects them in real-life situations is the potential interferences caused by intervening targets on the way to the primary one (distractors), a problem that is still largely understudied.

Surfpad [3, 4] is a pointing facilitation technique that does not decrease target distance or increase target width in either control or display space. This new technique operates instead in the tactile domain by taking advantage of the ability to alter a touchpad's coefficient of friction by means of a squeeze film effect [5]. We compared this technique to semantic pointing [6] and constant control-display gain with and without distractor targets. Our results clearly show the limits of traditional target-aware control-display gain adaptation in the latter case, and the benefits of our tactile approach in both cases. Surfpad leads to a performance improvement close to 9% compared to unassisted pointing at small targets with no distractor. It is also robust to high distractor densities, keeping an average performance improvement of nearly 10% while semantic pointing can degrade up to 100%. Our results also suggest the performance improvement is caused by tactile information feedback rather than mechanical causes, and that the feedback is more effective when friction is increased on targets using a simple step function.

References

[1] R. Balakrishnan. "Beating" Fitts' law: virtual enhancements for pointing facilitation. IJHCS, 61(6):857–874, 2004. [Google]

[3] G. Casiez, N. Roussel, R. Vanbelleghem and F. Giraud. Efficacité et robustesse aux distracteurs d'un retour tactile pour faciliter le pointage. In Proceedings of IHM 2010, 22ème conférence francophone sur l'Interaction Homme-Machine, pages 25-32, Septembre 2010. ACM, International Conference Proceedings Series. Prix du meilleur article. [ACM] [Google]

[4] G. Casiez, N. Roussel, R. Vanbelleghem and F. Giraud. Surfpad: riding towards targets on a squeeze film effect. In Proceedings of ACM CHI 2011 Conference on Human Factors and Computing Systems, pages 2491-2500, May 2011. ACM. Honorable mention (top 5% of all submissions). [ACM] [Google]

[5] M. Amberg, F. Giraud, B. Lemaire-Semail, P. Olivo, G. Casiez and N. Roussel. STIMTAC, a tactile input device with programmable friction. In Adjunct proceedings of UIST'11, the 24th ACM Symposium on User Interface Software and Technology, pages 7-8, October 2011. ACM. Best demo award, second place. [ACM] [Google]