Skilled Finger Movements in Typing.

Abstract : Six skilled typists were studied while they transcribed English text. The typists showed stable patterns of performance, but with significant individual differences among the typists. Inter-Keypress latencies for 2-finger digraphs (typed by two fingers on the same hand) were particularly variable among typists. Two typists showed large differences in 2-finger digraph latencies, but similar overall typing speeds. Finger movement trajectories, determined from analysis of videotapes of these typists, indicated that the differences in 2-finger digraph latencies correspond to differences in the independence of within-hand finger movements. A high-speed film of one typist showed that finger movements of this typist almost always overlapped. The starting times of movements were six times as variable as the ending times, suggesting that it is the completion rather than the initiation of the movements that is controlled in skilled typing. These studies demonstrate the importance of considering individual differences in constructing a theory of skilled human performance, even in a highly automatized task such as transcription typing. (Author)