http://repub.eur.nl/res/aut/36613/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/26644/ 2012-01-01T00:00:00Z The A-Not A difference test can be used to measure the overall sensory difference of two or more products from a reference product. It is an economically efficient method for difference testing because it is more statistically powerful and less prone to working memory problems than the triangle or duo-trio tests. With the A-Not A test, subjects are required to be familiar with the reference product to stabilize their cognitive decision criteria. An effective familiarization procedure is needed. In the present study, the effects of four different familiarization procedures were investigated: (1) 2-AFCR, (2) no-additional familiarization, (3) repeated tastings of the reference, and (4) repeated tastings of the reference with a brand image provided. Two products were discriminated from a reference using 12 subjects over repeated sessions. Comparisons of the test performances, analyzed with d' estimates, showed that there was a tendency toward better discrimination when repeated tastings of the reference were accompanied by a brand image. http://repub.eur.nl/res/pub/30727/ 2011-10-01T00:00:00Z To investigate more flexible methods for measuring overall sensory differences, the performance of three nonattribute-specified difference test methods was compared using Signal Detection Theory. A-Not A, 2-AFC, and 2-AFCR tests were performed with experienced subjects over repeated sessions. Learning effects were investigated to determine how much training would be needed before subjects could perform these tests consistently. Results in d' showed that in early sessions, the 2-AFC and 2-AFCR performed better (higher d') than A-Not A and that after two sessions, the test performance stabilized on that level. Learning effects for the A-Not A test were poorer in the earlier sessions, with performance levels increasing, even after six sessions. In business situations where the tested products frequently vary, the use of 2-AFC and 2-AFCR would be recommended because they are more sensitive in the earlier sessions, requiring less training time than A-Not A. PRACTICAL APPLICATIONS: Sensory difference tests are important tools for business decision making. Food companies may save a lot of money by employing more effective methodologies. For sensory difference tests to be used accurately and efficiently, test performances need to be investigated with consideration for food discrimination constraints and objectives. This article explored the performance of nonattribute-specified 2-AFC and 2-AFCR tests over several sessions in comparison to the results of a standard signal detection measure, A-Not A, to use the differences between these methods as a basis for inference concerning the cognitive strategies and relative test effectiveness of nonattribute-specified 2-AFC and 2-AFCR for food discrimination, in practical situations when both the reference product and test product(s) change frequently. This article suggested the applicability of a nonattribute-specified 2-AFCR procedure for discriminating small differences without much prior training.