Human Factors Engineering Studies of the Design and Use of Pushbutton Telephone Sets

From the user's point of view, what are the desirable characteristics of pushbuttons for use in 500-type telephone sets? The studies reported bear on this question and also on questions of how people process information when keying telephone numbers. Four categories of design features were studied: key arrangement, force-displacement characteristics, button-top design and central office factors. The results indicate that considerable latitude exists for key set design in terms of user performance; however, the preference judgments are more selective. The studies also showed that the manner in which the person acquired and keyed the telephone number influenced performance appreciably. Technological progress in recent years has brought pushbutton signaling from the telephone set within sight of economic feasibility. What, from the user's viewpoint, are the desirable operating characteristics of the key set which should guide development and manufacture? And how do people process information when they key a telephone number?