David F. Loricchio’s research while affiliated with International Electronic Machines Corporation and other places

The IBM Design Center in Boca Raton studied an integrated pointing device for a personal computer keyboard. The device, a pushbutton, is a flat, round button that tilts and moves the cursor in the direction of tilt. We wanted to know if this device would be acceptable to computer users. Twelve participants used the pushbutton, a mouse, and the cursor movement keys to select targets and edit text. Participants without previous mouse experience hit significantly more targets with the pushbutton than with the mouse. Participants with previous mouse experience performed significantly better on both tasks with the mouse, and preferred the mouse over the pushbutton and the cursor keys. Several participants said that the pushbutton was too sensitive and difficult to control. The results suggest: 1. The pushbutton tested in this study would not be acceptable to users; 2. The pushbutton operation could be more accurate if the force-to-motion mapping were improved.

The IBM Design Center in Boca Raton studied the operating-point key force for a portable computer keyboard. Alden, Daniels, and Kanarick (1972) report that typists prefer operating-point key forces of between 25 and 150 grams. We compared different key forces that fell within the range recommended by Alden et al. The only difference between the keyboards we studied was the amount of force required to activate the keys. The first keyboard (58 keyboard) required 58 grams of force to activate the keys. The second keyboard (74 keyboard) required 74 grams of force to activate the keys. Sixteen skilled typists used both keyboards to enter text. Input speed was significantly faster on the 58–gram keyboard. A significant number of typists preferred the 58-gram keyboard. The results suggest that the optimal key force for portable computer keyboards is less than 74 grams.

As technology improves, portable computers become smaller and more compact. A clear design challenge is to provide a system that is as compact as possible without degrading system usability. The keyboard is still the primary input device for compact computers. Previous research has indicated that reduced key spacing adversely affects skilled typing. Therefore, a portable computer system should provide a keyboard with full-sized keys in the primary typing area. The purpose of this study was to determine if reducing key size and spacing adversely affects the usability of a numeric keypad. Skilled keypad operators compared a standard-size numeric keypad to two keypads that had reduced center-to-center key spacing. One of these keypads achieved its reduction primarily by reducing the key spacing. The other reduced both key size and spacing. (Note that the small changes in key size and spacing have little effect on the overall device dimensions of a numeric keypad.) Operators typed numbers faster with and preferred the standard keypad over the keypad with both reduced key size and key spacing. If a numeric keypad is offered as part of a portable computer, every effort should be made to provide full-sized keys. If reduced key spacing is unavoidable, wide keys are preferable to narrow keys.