Effects of Randomly Delayed Visual and Auditory Feedback on Keying Performance†

Abstract

An experiment is reported, which assessed the effect on keyboard performance of increasing the length of time intervening between depressing a key and the associated activation of the printer mechanism, termed ‘ delay time’ Sixteen skilled subjects keyed text on a teletype under conditions in which delay time was manipulated as the independent variable. The increase in delay time resulted in significantly worse keying performance as reflected by measures of both speed and accuracy. The data suggested that efficiency of performance was reduced by the delay to both visual and auditory feedback, as well as by the limit imposed on the output rate of the teletype. The results are related to the assumed functions of visual and auditory feedback under normal keying conditions and the advantages and disadvantages of the insertion of a buffer-store between teletype and transmission system are discussed. Ways of reducing performance impairment are proposed.