A Theoretical Note on Difference Tests: Models, Paradoxes and Cognitive Strategies

A simple nonmathematical introduction is given to Thurstonian modeling and its application to difference testing. The theoretical treatment explains differences in performance noted for various difference test protocols and the so‐called paradox of discriminatory nondiscriminators, whereby a slight change in instructions to the judge can alter the proportion of tests performed correctly. From this, the assumptions in the use of binomial statistics for analyzing difference tests and their shortcomings, are discussed. New ideas on the generality of the paradox of discriminatory nondiscriminators are discussed, along with the effects of the cognitive strategy adopted by the judge during testing.