Updating Fitts' Law to Account for Small Targets

The use of small display devices is becoming more prevalent in our daily lives, such as smart phones, ultramobile PCs, and even head-mounted displays. Usually, the graphical user interface components shown on these displays are small and often difficult to interact with. Although some prior work has shown that Fitts' law does not hold for small target size, a detailed investigation of Fitts' law in different small target size conditions has yet to be done. In this study we conducted two experiments investigating the impact of small target sizes on pointing performance. We identified a critical point on the target size dimension where Fitts' law started to break down. We then proposed a small target size index of difficulty and an empirical Fitts' formula to extend the Fitts' law beyond the critical point to small target size conditions. Our results show that the new model works well as both a descriptive and a predictive model for small target size conditions.

[1]  Shumin Zhai,et al.  Characterizing computer input with Fitts' law parameters-the information and non-information aspects of pointing , 2004, Int. J. Hum. Comput. Stud..

[2]  Michael Bohan,et al.  Kinematic analysis of multiple constraints on a pointing task. , 2007, Human movement science.

[3]  Michael Bohan,et al.  KINEMATIC ANALYSIS OF MOUSE CURSOR POSITIONING AS A FUNCTION OF MOVEMENT SCALE AND JOINT SET , 2003 .

[4]  Kim J. Vicente,et al.  An experimental evaluation of transparent menu usage , 1996, CHI.

[5]  Martina Ziefle,et al.  Psychomotor Efficiency in Users of Notebook Input Devices: Confirmation and Restrictions of Fitts' Law as an Evaluative Tool for User-Friendly Design , 2004 .

[6]  C R Cavonius,et al.  Human Visual Acuity Measured with Colored Test Objects , 1966, Science.

[7]  Sang Joon Kim,et al.  A Mathematical Theory of Communication , 2006 .

[8]  W. Dixon,et al.  Simplified Statistics for Small Numbers of Observations , 1951 .

[9]  Morten Hertzum,et al.  How Age Affects Pointing With Mouse and Touchpad: A Comparison of Young, Adult, and Elderly Users , 2010, Int. J. Hum. Comput. Interact..

[10]  P. Fitts.  The information capacity of the human motor system in controlling the amplitude of movement. , 1954, Journal of experimental psychology.

[11]  Cbema Computer,et al.  Guide to the draft American national standard for human factors engineering of visual display terminal workstations , 1985 .

[12]  I. Scott MacKenzie,et al.  An error model for pointing based on Fitts' law , 2008, CHI.

[13]  Atsuo Murata,et al.  Extending Effective Target Width in Fitts' Law to a Two-Dimensional Pointing Task , 1999, Int. J. Hum. Comput. Interact..

[14]  Hiroshi Ishii,et al.  Transparent layered user interfaces: an evaluation of a display design to enhance focused and divided attention , 1995, CHI '95.

[15]  I. Scott MacKenzie,et al.  Towards a standard for pointing device evaluation, perspectives on 27 years of Fitts' law research in HCI , 2004, Int. J. Hum. Comput. Stud..

[16]  C. E. SHANNON,et al.  A mathematical theory of communication , 1948, MOCO.

[17]  W. Helsen,et al.  A century later: Woodworth's (1899) two-component model of goal-directed aiming. , 2001, Psychological bulletin.

[18]  J. Shawn Farris,et al.  Kinematic Analysis of Cursor Trajectories Controlled With a Touchpad , 2005, Int. J. Hum. Comput. Interact..

[19]  Yves Guiard,et al.  The problem of consistency in the design of Fitts' law experiments: consider either target distance and width or movement form and scale , 2009, CHI.

[20]  Martina Ziefle,et al.  Considerations on Efficient Touch Interfaces - How Display Size Influences the Performance in an Applied Pointing Task , 2007, HCI.

[21]  R A Abrams,et al.  Optimality in human motor performance: ideal control of rapid aimed movements. , 1988, Psychological review.