Fitts' law in two-dimensional task space
A traditional continuous Fitts' task may be described as a one-dimensional oscillation between two targets. The combination of two such oscillations along intersecting axes gives rise to a two-dimensional aiming task, allowing the study of the speed-accuracy trade-off in two-dimensional task space. In two experiments subjects were asked to draw as many ellipses as possible while passing through four targets, arranged around the extreme points of the two major axes of a model ellipse. In the first experiment, task difficulty was manipulated simultaneously along the two axes of the ellipse. Regardless of ellipse eccentricity and orientation, movement time (MT) was found to depend linearly on Fitts' index of difficulty (ID), which combines between-target distance and target width. In the second experiment, ID was manipulated independently for the short and the long axes of the ellipse. There was a strong linear relation between MT and ID averaged over the two axes, with the two independent measures of task difficulty exerting interactive effects on MT: the higher the ID on one axis, the smaller the effect of the ID on the other. The present results demonstrate that Fitts' law, only examinated so far in one-dimensional aiming tasks, generalises to two-dimensional task space.
Key wordsMotor control Speed-accuracy trade-off Two-dimensional task space Human
Unable to display preview. Download preview PDF.
- Abernethy B, Sparrow WA (1992) The rise and the fall of dominant paradigms in motor behaviour research. In: Summers JJ (eds) Approaches to the study of motor control and learning. North-Holland, Amsterdam, pp 3–45Google Scholar
- Crossman ERF, Goodeve PJ (1963/1983) Feedback control of hand movements and Fitts' law. Q J Exp Psychol [A] 35:251–278 (Original work presented at meeting of Experimental Psychology Society, Oxford, England, July 1963)Google Scholar
- Kelso JAS, Southard DL, Goodman D (1979) On the nature of interlimb coordination. Science 203:1029–1031Google Scholar
- MacKenzie CL, Marteniuk RG, Dugas C, Eiske D, Eickmeier B (1987) Three dimensional movement trajectories in Fitts' task: implications for control. Q J Exp Psychol [A] 39:629–647Google Scholar
- Meyer DE, Abrams RA, Kornblum S, Wright CE, Smith JEK (1988) Optimality in human motor performance: ideal control of rapid aimed movements. Psychol Rev 95:340–370Google Scholar
- Saltzman E, Kelso JAS (1987) Skilled actions: A task dynamic approach. Psychol Rev 94:84–106Google Scholar
- Schmidt RA (1988) Motor control and learning: a behavioral emphasis (2nd edn). Human Kinetics, Champaign, ILGoogle Scholar
- Schmidt RA, Zelaznik HN, Frank JS (1978) Sources of inaccuracy in rapid movement. In: Stelmach GE (eds) Information processing in motor control and learning. Academic, New York, pp 183–203Google Scholar
- Welford AT (1968) Fundamentals of skill. Methuen, LondonGoogle Scholar
- Woodworth RS (1899) The accuracy of voluntary movement. Psychol Rev [Mon Suppl 3] 3Google Scholar