This article was initially published in Today's Engineer on August 2006

Usability has gained a great deal of well-deserved attention in recent years, stimulated in large part by Web site design and usability. A number of large conferences are devoted to usability, books are written on the subject, and many companies hire consultants or have established entire departments to evaluate the usability of their designs.

Many early electrical pioneers seemed to have had an intuitive grasp of what we now call user-friendly design. The triumph of Morse's telegraph over competitors' models came about largely because of the usability of Morse code. Morse's competitors-- and originally Morse himself-- relied on numerical codes, which then had to be translated by means of a dictionary into letters and words. Not only was this cumbrous for the operator, it also meant time and expense on the part of the inventor.

Morse's assistant, Alfred Vail, thought it would make the telegraph much more efficient if the translation step could be dispensed with and the information transmitted by letter. Vail took the further user-friendly step of assigning the simplest and shortest code combinations to the most frequently used letters. In a brilliant grasp of user-friendliness, he counted the slugs in the compositors' type cases at the office of a newspaper in Morristown, New Jersey, to determine which characters were used most frequently.

The telephone-- one of the earliest electrical technologies intended to be used directly by the public (as opposed to the telegraph, where trained operators provided the interface between the customer and the technology)-- is another example of how usability influenced design and acceptance.

The 1882 three-box telephone, the first telephone manufactured by Western Electric, freed one of the user's hands by mounting the transmitter into the unit so that only one hand was needed for holding the receiver to the ear. A writing shelf was incorporated in the design, in deference to the fact that conversing by telephone frequently means exchanging information which needs to be written down. As early as 1877, it was recognized that ease of use would be further served if the transmitter and receiver were together in a hand-held unit. Two Englishmen, C. E. McAvoy and G. E. Pritchett, were awarded patents on such a handset, and Robert Brown obtained a U.S. patent for a combined handset the following year. However, in this case, it took some time for the technology to catch up with the convenience. The early handsets were vulnerable to acoustic feedback, as well as variations in performance if the user moved his or her head, causing the carbon granules to fall away from the electrodes. By 1919, these problems had been solved, and the combined handset was available.

Some other simple, but very important usability advances for telephone design were putting the numbers outside of the fingerwheel dial instead of behind the holes so that the fingerwheel would not obscure them while rotating (1949), and including a subscriber-operated ringer-volume control. Allowing the subscriber to adjust the volume meant a huge savings for the Bell System in reducing the amount of service calls which technicians had to make.

Edison's lightbulb socket, with its spiral screw, is another example of intuitive usability. For two years after the invention of the practical incandescent lightbulb, the fragile bulbs were difficult to install and were easily knocked loose. In order to become widely accepted, something less frustrating for the customer needed to be invented. What the Edison company came up with, however, was less a new invention than an adaptation of one which was sanctioned by years of familiar use: the screw socket.

The explanation for the design is that Edison-- or one of Edison's assistants who was standing near as Edison cleaned his hands with kerosene-- got the idea from the screw cap of the kerosene can. Not only did the simplicity of Edison's base advance customer acceptance of Edison's light bulb over those of rivals, its ease of use generated a market for lamp socket connectors which would allow electrical appliances to be plugged into the Edison-type lamp sockets, rather than having to be permanently wired into the building's electricity supply.

These are just a few examples of the many world-changing innovations which have benefited from their developers' grasp of the importance of the "human effect."