Movement Time to an Array of Controls

Abstract

Two tasks in which subjects aim at an array of devices were considered: moving to one knob within an array and moving the finger on a numeric keypad. It was shown by a mathematical model based on Fitts' law, that when the array density is specified for the array of knobs or keys, there is an optimum control size for minimum movement time. The theoretical result was obtained by considering a two-element model of the movement, the first being a reach to the general location of the control and the second describing the insertion of the fingers into the space between adjacent controls. As the first element has a movement time that decreases with increase of control size and the second a time increasing with control size, there is an optimum control size where the movement time is a minimum.

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References

Alden

D.G.

Daniels

R.W.

Kanarick

A.R.

(1972). Keyboard design and operation: A review of the major issues. Human Factors, 14, 275–293.

Armstrong

Hoffmann

E.R.

(1990). Perceived relationship between elements of a complex display. Ergonomics, 33, 109–120.

Bradley

J.V.

(1969). Optimum knob crowding. Human Factors, 11(3), 227–238.

Bradley

J.V.

Wallis

R.A.

(1958). Spacing of on-off controls. 1: Pushbuttons. Wright-Patterson Air Force Base, OH: Wright Air Development Center. WADC-TR 58–2.

Card

S.K.

Moran

T.P.

Newell

(1983). The Psychology of Human-Computer Interaction. Laurence Erlbaum, Hillsdale, NY.

Chung

C.S.

(1983). A study of human arm movements with applications to predetermined motion time systems. Unpublished Master's thesis, University of Melbourne, Australia.

Drury

C.G.

(1975). Application of Fitts' law to foot-pedal design. Human Factors, 17, 368–373.

Drury

C.G.

Hoffmann

E.R.

(1992). A model for movement time on data-entry keyboards. Ergonomics, 35, 129–147.

Fitts

P.M.

Peterson

J.R.

(1964). Information capacity of discrete motor responses. Journal of Experimental Psychology, 67, 103–112.

10.

Gan

K.C.

Hoffmann

E.R.

(1988). Geometrical conditions for ballistic and visually controlled movements. Ergonomics, 31, 829–839.

11.

Hoffmann

E.R.

(1981). An ergonomics approach to predetermined motion time systems. Proceedings, Institute of Industrial Engineers, Australia, Ninth National Conference, 30–47.

12.

Hoffmann

E.R.

(1994). Effective target tolerance in an inverted Fitts task. To be published in Ergonomics.

13.

Wiker

S.F.

Langolf

G.D.

Chaffin

D.B.

(1989). Arm posture and human movement capability. Human Factors, 31(4), 421–441.