Cognitive Decision Strategies Adopted in Reminder Tasks by Trained Judges When Discriminating Aqueous Solutions Differing in the Concentration of Citric Acid

Abstract

Four sensory difference tests -A-Not A, two-alternative forced choice (2-AFC) and their reminder counterparts, A-Not A with reminder task (A-Not AR) and 2-AFC with reminder task (2-AFCR) -were applied to pairs of aqueous solutions containing different concentrations of citric acid to determine the decision strategy adopted by judges in the reminder tasks, and which of the four tasks has the greatest test sensitivity. Three solution types, each containing a different number of compounds, were employed to determine if the strategy adopted or test sensitivity is contingent upon the number of compounds in solution. Auditory and visual research suggests that observers adopt a tau (t) strategy for simple stimuli (which could be likened to a solution containing a few compounds) and a beta (b) strategy for complex stimuli (which could be likened to a solution containing several compounds). Results suggest that the strategy adopted for the 2-AFCR task is fairly consistent across judges and solution types, whereas that for A-Not AR is fairly consistent across judges but depends on solution type. All four tasks were found to have similar test sensitivity. The results highlight the need for caution when using difference tests when the decision strategy being used by judges is not known. Relatively large errors in estimates of performance can result from an incorrect assumption. PRACTICAL APPLICATIONSChanges to ingredients, processing and storage methods frequently challenge manufacturers who strive to maintain products that will appeal to consumers. Difference tests can assist the manufacturer in determining the effect of such changes on perception. Difference tests need to be effective in use and must produce valid and reliable results. A-Not A and 2-AFC tasks are sensitive to sensory differences, and are frequently used, but require a time-consuming familiarization procedure. A-Not AR and 2-AFCR do not require this, as they provide a comparative reminder stimulus on each trial. Comparisons of these four tasks showed all to be equal in test sensitivity, a component of validity, however, not equal in reliability. Of the reminder tasks, A-Not AR was less reliable, as decision strategy depended on stimulus type, whereas in 2-AFCR, decision strategy was more consistent, particularly for stimuli containing more components.

Sensory discrimination by consumers of multiple stimuli from a reference: Stimulus configuration in A-Not AR and constant-ref. duo-trio superior to triangle and unspecified tetrad?

“…Yet, in recent publications, the relative efficiencies of different overall discrimination test methods have been actively discussed using only a fixed design where the stimuli to be http://dx.doi.org/10.1016/j.foodqual.2015.06.021 0950-3293/Ó 2015 Elsevier Ltd. All rights reserved. discriminated from each other include only a pair of stimuli (2 stimulus types) (Choi, Kim, Christensen, van Hout, & Lee, 2014;Ennis & Christensen, 2014a, 2014bKim, Chae, van Hout, & Lee, 2014;McClure & Lawless, 2010;Olivas, Lopez-Malo, Angulo, & O'Mahony, 2014;Stocks, van Hout, & Hautus, 2013, 2014van Hout, Hautus, & Lee, 2011). Also, the relative test power of the various discrimination test methods have been only investigated based on the same numbers of tests (Bi, 2011;Ennis, 1993;Ennis & Jesionka, 2011;Jesionka, Rousseau, & Ennis, 2014;Kim et al, 2014;Schlich, 1993).…”

Comparing motion capture cameras versus human observer monitoring of mammal movement through fence gaps: a case study from Kenya

“…The observers at our study site were highly trained, but their judgments were, by necessity, based on incomplete physical evidence. All human judgments are subject to some degree of error (Harris, 1915;Diefenbach, Brauning & Mattice, 2003), even in skilled observers (Taylor, Skourides & Alvero, 2012;Stocks, van Hout & Hautus, 2013). However, it is unlikely that the disagreement or detection differences were due entirely to human error.…”

Optimal difference test sequence and power for discriminating soups of varying sodium content: DTFM version of dual-reference duo–trio with unspecified tetrad tests

“…more powerful than both specified and unspecified tetrad tests. For the 2-AFCR method in SDT, either the 2-AFC β/τ-strategy or the 2-AFCR τ-strategy were proposed (Hautus et al, 2009), and recently, these models have been confirmed by using trained subjects who evaluated the samples over several days to discriminate various simple food systems in a fixed experimental design (Stocks, van Hout, & Hautus, 2013, Stocks, van Hout, & Hautus, 2014; van Hout, Hautus, & Lee, 2011).…”