KEYBOARD USER VERIFICATION - TOWARD AN ACCURATE, EFFICIENT, AND ECOLOGICALLY VALID ALGORITHM

This paper proposes new measures of individual differences in typing b ehaviour which provide a means of accurately verifying the identity of the typist. A first study examined the efficacy of a multivariate mea sure of inter-key latencies and a probabilistic discriminator statisti c in conjunction with an individual filtering system which eliminates occasional disfluent keystrokes. The results indicate that, under opti mum conditions but with a very small test sample, these measures lead to better typist verification than measures suggested earlier by Umphr ess and Williams and then Leggett and Williams. A second study validat ed the improved algorithm under more ecologically valid conditions and showed that when training and test sessions were separated by one wee k, typist verification using the new algorithm achieved combined false -acceptance and false-rejection rates of 0.9% and 3.8% for test sample s of 300 and 50 digraphs respectively. (C) 1995 Academic Press Limited