Publications

Our publications

• J. Aceituno, G. Casiez and N. Roussel. How low can you go? Human limits in small unidirectional mouse movements. In *Proceedings of CHI'*13, p. 1383-1386, April 2013. ACM.

  • Computer mouse sensors keep increasing in resolution. The smallest displacement they can detect gets smaller, but little is known on our ability to control such small movements. Small target acquisition has been previously tackled, but the findings do not apply to the problem of finding the useful resolution of a user with a mouse, which corresponds to the smallest displacement (s)he can reliably produce with that device. We detail this definition and provide an associated experimental protocol to measure it. We then report on the results of a study suggesting that high-end mice are not likely to be used to their full potential. We further comment on the different strategies used by participants to acheive best performance, and derive implications for user interfaces.

• P. Quinn, A. Cockburn, G. Casiez, N. Roussel and C. Gutwin. Exposing and understanding scrolling transfer functions. In Proceedings of UIST'12, p. 341-350, October 2012. ACM.

  • Scrolling is controlled through many forms of input devices, such as mouse wheels, trackpad gestures, arrow keys, and joysticks. Performance with these devices can be adjusted by introducing variable transfer functions to alter the range of expressible speed, precision, and sensitivity. However, existing transfer functions are typically "black boxes" bundled into proprietary operating systems and drivers. This presents three problems for researchers: (1) a lack of knowledge about the current state of the field; (2) a difficulty in replicating research that uses scrolling devices; and (3) a potential experimental confound when evaluating scrolling devices and techniques. These three problems are caused by gaps in researchers' knowledge about what device and movement factors are important for scrolling transfer functions, and about how existing devices and drivers use these factors. We fill these knowledge gaps with a framework of transfer function factors for scrolling, and a method for analysing proprietary transfer functions — demonstrating how state of the art commercial devices accommodate some of the human control phenomena observed in prior studies.

• N. Roussel, G. Casiez, J. Aceituno and D. Vogel. Giving a hand to the eyes: leveraging input accuracy for subpixel interaction. In Proceedings of UIST'12, p. 351-358, October 2012. ACM.

  • We argue that the current practice of using integer positions for pointing events artificially constrains human precision capabilities. The high sensitivity of current input devices can be harnessed to enable precise direct manipulation "in between" pixels, called subpixel interaction. We provide detailed analysis of subpixel theory and implementation, including the critical component of revised control-display gain transfer functions. A prototype implementation is described with several illustrative examples. Guidelines for subpixel domain applicability are provided and an overview of required changes to operating systems and graphical user interface frameworks are discussed.

• G. Casiez and N. Roussel. No more bricolage! Methods and tools to characterize, replicate and compare pointing transfer functions. In Proceedings of UIST'11, pages 603-614, October 2011. ACM.

  • Transfer functions are the only pointing facilitation technique actually used in modern graphical interfaces involving the indirect control of an on-screen cursor. But despite their general use, very little is known about them. We present EchoMouse, a device we created to characterize the transfer functions of any system, and libpointing, a toolkit that we developed to replicate and compare the ones used by Windows, OS X and Xorg. We describe these functions and report on an experiment that compared the default one of the three systems. Our results show that these default functions improve performance up to 24% compared to a unitless constant CD gain. We also found significant differences between them, with the one from OSX improving performance for small target widths but reducing its performance up to 9% for larger ones compared to Windows and Xorg. These results notably suggest replacing the constant CD gain function commonly used by HCI researchers by the default function of the considered systems.