ABSTRACT
Unfortunately for the experimenter, not all detection tasks involve signal and noise distributions with equal variances. In these cases we cannot infer the entire ROC curve from a single pair of hit and false alarm probabilities but need a set of points for the curve. This means that while a single yes no task is sufficient to estimate in the equal variance case, a series of yes-no tasks, or a rating scale task, is necessary to determine sensitivity when variances are not equal.
