SSL-77-1_Evaluation_of_Mouse_Rate-Controlled_Isometric_Joystick_Step_Keys_and_Text_Keys_for_Text

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EVALUATION OF MOUSE,
RATE-CONTROLLED ISOMETRIC JOYSTICK,
STEP KEYS, AND TEXT KEYS
FOR TEXT SELECTION ON A CRT
BY STUART K. CARD, WILLIAM K. ENGLISH, AND BETTY BURR

APRIL 1977

SSL-77-1

ABSTRACT

Four devices are evaluated with respect to how rapidily they can be used to select text
on a CRT display. The mouse is found to be fastest on all counts and also to have the
lowest error rates. It is shown that variations in positioning time with the mouse and
joystick are accounted for by Fitts's Law. In the case of the mouse, the measured Fitts's
Law slope constant is close to that found in other eye-hand tasks leading to the
conclusion that positioning time with this device is almost the minimal achievable.
Positioning time for the key devices is shown to be proportional to the number of
keystrokes which must be typed.

KEY WORDS AND PHRASES

pointing device, target aquisition, step tracking, mouse, joystick, step keys, text keys,
text-editing, Fitts's Law

CR CATEGORIES

3.36, 8.1

XEROX
PALO ALTO RESEARCH CENTER
3333 Coyote Hill Road I Palo Alto I California 94304
An important element in the design of the man-computer interface is the
method of pointing by which the user indicates to the computer his selection
of some element on the computer display. This is especially important for