THE MEASUREMENT OF TASTE DISCRIMINATION WITH THE SAME‐DIFFERENT TASK: A DETECTION‐THEORY ANALYSIS

Abstract

ABSTRACT The biases to which the same‐different task is prone can be accounted for by having subjects rate their confidence that two stimuli are the same or different. The rating method of detection theory was therefore used to study the discriminability of two concentrations of a fruit drink. A model in which the decision variable was the difference in sensory strength of the two samples provided a satisfactory fit to the Receiver Operating Characteristics of four of the five subjects. The bias‐free index of discriminability, d′, was estimated for each subject. A combined operating characteristic, derived from jackknifing the data of the individual subjects, revealed an asymmetry characteristic of the differencing model. The results suggest that the same‐different task, which is readily understood by subjects, can provide an unbiased measure of the discriminability of foods or beverages.