Drawing typists' attention to their hands by asking them to type only letters assigned to the left or the right hand disrupts their performance, slowing the rate of typing and increasing errors. In this article we test the hypothesis that slowing occurs because typists watch their hands to determine which hand types which letter. Skilled typists were cued to type letters of one hand or of both hands while they could view their hands on the keyboard and while their vision was blocked by a box placed over the keyboard. Typing was slower when letters of one hand were typed than when letters of both hands were typed, and the slowing was greater when the hands were covered than when they were not. This supports the hypothesis that slowing occurs because typists watch their hands. However, typists were able to type letters of one hand when the keyboard was covered, so typists must have monitored kinesthetic information as well.

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