Evidence against a Central Control Model of Timing in Typing.

Terzuolo and Viviani, in widely cited research, propose a central control model of timing in typing, in which keystroke times are generated in parallel from centrally stored, word-specific timing patterns. Differences in overall time to type a given word are attributed to a multiplicative rate parameter, constant for a given typing of the word, but varying from one typing to another. Three major lines of evidence are cited for this model: (a) keystroke times expand or contract proportionally when words are typed slower or faster; (b) in a word; (c) the times to type a given digraph exhibit word-specific differences. My analyses show that (a) keystroke times do not expand proportionally; (b) the apparent constancy of variances is an artifact of the method that Terzuolo and Viviani used to transform the keystroke times; (c) the effects of surrounding character context are sufficient to explain differences in digraph latencies and these effects cross word boundaries, showing that they are not word-specific. (Author)