“Man-Computer Symbiosis”

“Man-Computer Symbiosis” is the title of a paper published in 1960 by American psychologist J. C. R. Licklider (1915–90). It outlines the author's personal vision of what in the following years became known as interactive computing. Licklider envisioned that “human brains and computing machines will be coupled together very tightly, and that the resulting partnership will think as no human brain has ever thought and process data in a way not approached by the information-handling machines we know today.” His vision has guided the development of artificial intelligence, hypertext, and other advances in computing.

The central idea of Licklider's paper is based on the fact that computers and humans have very different capabilities. Computers operate sequentially and quickly on narrowly defined tasks; humans can easily handle a much wider range of tasks, some even in parallel, but are considerably slower. When combined, the capabilities of humans and computers would complement each other, with the effect of dramatically increasing the intellectual capabilities of the computer user.

In order to accomplish this combination, according to Licklider, computer science would have to move beyond what had by then already been accomplished—namely, the partial automation of tasks formerly carried out by humans. Automation had been identified as an increasingly desirable technology during World War II, as mechanized battle systems gradually outpaced the reaction time and motor skills of the human operator. With the establishment of the SAGE (Semi-Automatic Ground Environment) early warning system of the 1950s, this kind of man-machine integration had become reality. SAGE used radar (Radio Detection and Ranging) and computers equipped with cathode-ray tube (CRT) screens and lightpens to help operators detect incoming airplanes.

Even though it served as an inspiration to Licklider, the SAGE system was not what he had in mind. His use of the word “symbiosis,” which literally means “living together,” points toward a much more active role for the machine component of the equation. Licklider's example of symbiosis, which involved a kind of larvae living in trees, is characterized by a mutual interdependence where both parties play an active role. In order to become more active, the machine would have to be able to contribute to the formation of conceptual models, and to acquire the kind of problem-solving skills envisioned by such artificial-intelligence researchers as Allen Newell and Herbert Simon. At the time of Licklider's writing, it was thought that true artificial intelligence was only a few years from realization. However, present-day computers still do not have such capabilities.

In addition to a more active participation by computers, the interchange between man and machine would have to proceed uninterrupted, or in real time. The cost of computers in 1960 dictated that they be shared by multiple users. The predominant mode of computer use was batch processing, which used punched cards or tape for data input and output, as well as printed paper for output. Users were allocated computer time based on the priority of their jobs, and frequently had to wait for hours or days before receiving results. In contrast, real-time computing required sub-second response times for which other input/output devices were clearly needed, such as the screen, keyboard, and mouse of present-day personal computers. Users of real-time systems still had to share the computer between them, but it switched so rapidly between users as it served them that each user had the illusion of being the only one using the computer. This process, referred to as time-sharing, was used extensively in the 1960s and 1970s but has mostly been replaced by the use of personal computers.

...