Establishing the Consumer Relevance of a Sensory Difference Using the Same-different Method

John Castura
Vice President of Research & Innovation

Establishing the consumer relevance of a sensory difference is essential to reach a conclusion of “similarity” or “difference”. Rousseau and Ennis (2013) propose conducting a designed same-different study using a Thurstonian-derived model to obtain discriminal sensory distances (d’) and the consumer-based threshold tau. This threshold corresponds to a decision boundary where a momentary sensory distance between two products will result in a "same" response if smaller than tau, a "different" response otherwise. Thus, tau may be interpreted as a quantification of consumer relevance.

We conducted an empirical consumer study to evaluate this proposal. In addition to collecting same-different data from consumers, we collected tetrad results in order to compare the discriminal distances estimated with each method. Results indicate that d’ estimates from the tetrad method are lower than those from the same-different method (this could be due at least in part to increased perceptual noise) and that the tau estimate from the same-different must be adjusted if it is to serve as the consumer relevance threshold when using the tetrad test method. In this presentation, we will outline the successive steps that were followed and provide suggestions for future consumer relevance investigations.