Influence of sensitivity on response bias in taste and audition

A detection theoretic analysis was employed to examine sensitivity and resp onse bias in two modalities. In Experiment 1, 6 tasters made same-different judgments about the concentration of either sucrose or quinine in pairs of tonic water samples. The beverages were colored, but color was not predict ive of the concentration of the sweet or bitter ingredient. When same-diffe rent ratings were collapsed to approximate the outcome of a categorical dec ision, tasters with poorer sensitivity appear to have adopted more extreme response criteria than did tasters with greater sensitivity, irrespective o f taste quality, color, or whether pairs of solutions comprised the same or different colors. In Experiment 2, 3 individuals discriminated pairs of 10 00-Hz sinusoids differing in amplitude. Six amplitude differences were test ed. Rating-scale versions of two paradigms: The single-interval yes-no task and the two-interval same-different task were used to measure sensitivity and bias. There was a preponderance of "same" responses in the same-differe nt task. Estimates of bias obtained from collapsed ratings in both tasks we re unaffected by sensitivity, but a consideration of the range over which s ets of criteria were spread suggested a general tendency toward more conser vative response biases as sensitivity declined.