Vigilance and Signal Detection Theory: An Empirical Evaluation of Five Measures of Response Bias

Three experiments were conducted to determine which of five response bias indices (β, c, B", B' H and B" D ) defined by the theory of signal detection provides the most effective measure of the observer's willingness to respond in a vigilance task. The results indicated that the traditional parametric bias index β was an inadequate measure of response bias in every respect, whereas the newer parametric measure c was the most effective of all five indices. When the three nonparametric measures (B", B' H' and B" D ) were examined separately, B" D emerged as the most effective nonparametric index. We recommend that vigilance researchers use c rather than β to measure bias when a parametric model is involved and B" D instead of B" and B' H when a nonparametric model is used.