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.