Proceedings of the Annual Meeting of the Cognitive Science Society

We review the major phenomena of skilled typing and propose a model of the control of the hands and fingers during typing. The model is based upon an Activation-Trigger-Schema system in which a hierarchical structure of schemata directs the selection of the letters to be typed and, then, controls the hand and finger movements by a cooperative, relaxation algorithm The interactions of the patterns of activation and inhibition among the schemata determine the temporal ordering for launching the keystrokes To account for the phenomena of doubling errors, the model has only "type" schemata -- no "token" schemata - with only a weak binding between the special schema that signals a doubling and its argument. The model exists as a working computer simulation and produces an output display of the hands and fingers moving over the Keyboard and it reproduces some of the major phenomena of typing, including the interkeypress latency times, the pattern of transposition errors found in skilled typists, and doubling errors. Although the model is clearly inadequate or wrong in some of its features and assumptions, it serves as a useful first approximation for the understanding of skilled typing.