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RISS 인기검색어
- 검색키워드
- 저자 : Hautus, M. J. (검색결과 6 건)
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Variants of A Not-A and 2AFC tests: Signal Detection Theory models
Hautus, M.J.,van Hout, D.,Lee, H.S. Longman Scientific Technical ; Elsevier Science Pu 2009 Food quality and preference Vol.20 No.3
Signal Detection Theory provides an approach to modelling difference test procedures that allows an estimate of the sensory difference between products to be obtained independently of the response bias and decision strategy used by the judge, and of the test procedure used to estimate that difference. The estimate of sensory difference obtained, d', is therefore much closer to a 'true' estimate of sensory difference than many other measures employed by sensory scientists. The methods used to generate models based on Signal Detection Theory are standard, and these methods are applied to the development of models for two test procedures (A Not-A and 2AFC) and their reminder equivalents (A Not-AR and 2AFCR). 2AFCR is procedurally identical to the duo-trio procedure with a constant reference; however, it is shown that there is more than one decision strategy available to the judge in this task.
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Shin, H.K.,Hautus, M.J.,Lee, H.S. Published on behalf of the Canadian Institute of F 2016 Food Research International Vol.79 No.-
<P>Using signal detection theory (SDT) and Thurstonian analysis, it has been possible in the food industry to make various business decisions such as reformulations and cost reductions based on the degree of consumer sensory discriminability by applying equivalence/difference testing. To achieve more efficient decision-making, it is important to investigate a theoretically and operationally more powerful consumer discrimination test method. Cognitive decision strategies used in discrimination methods largely determine relative test power and thus are of theoretical and practical significance. The goal of this study was to investigate if test procedures using a constant-ref. duo-trio design enable untrained/naive subjects to use a powerful 2-AFC strategy. Although previously the constant-ref. duo-trio design showed operational superiority to other unspecified test methods, the 'comparison of distance' (COD) strategy which is conventionally assumed for the duo-trio, lacks theorized power. The tested variables included two versions of duo-trio design, different familiarizations, instructions and experimental session designs. Three different iced tea samples were discriminated from a reference by 263 untrained/naive subjects using 5 different duo-trio test procedures. Results showed that untrained/naive subjects were able to perform the duo-trio with the reference presented twice, first and middle (DTFM) as a 2-AFC procedure, even with multiple pairs in a block design, after only two reference tastings with the information of the constant-reference. The duo-trio preceded by specified tetrad tests also showed potential as another efficient two-sequence test design. These results suggest that such constant-ref. duo-trio protocols using a 2-AFC strategy can be an alternative to the unspecified triangle and tetrad test. (C) 2015 Elsevier Ltd. All rights reserved.</P>
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Lee, H.S.,van Hout, D.,Hautus, M.J. Longman Scientific Technical ; Elsevier Science Pu 2007 Food quality and preference Vol.18 No.6
The performance of three different discrimination tests (A-Not A, 2-AFC, same-different) was investigated to explore the effects of varying aspects of the test protocols, such as the familiarization procedure and retasting of the reference (A), during testing on discriminability and the cognitive decision strategy used in the tests, when discriminating between the two different margarines. Seven judges, who were not familiar with margarine products, each gave 24 ratings for each of six protocols, resulting in 168 ratings in the pooled data, and from which R-indices and d' estimates were calculated. When both test products were presented beforehand for familiarization, judges adopted the beta cognitive decision strategy. When only the reference (A) was presented to the judges beforehand for familiarization, and the reference (A) was retasted before the test product either by prescription or at will, the tau cognitive decision strategy was adopted. When the number of samples tasted within a test increased, discriminability was considerably decreased. Such differences between test protocols were explained in terms of the concept formation of the test products, carry-over and fatigue effects, and memory problems caused by longer time-intervals between tastings.
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Jeong, Y.N.,Kang, B.A.,Jeong, M.J.,Song, M.J.,Hautus, M.J.,Lee, H.S. Longman Scientific Technical ; Elsevier Science Pu 2016 Food quality and preference Vol.47 No.1
<P>In the food industry, overall discrimination tests are used with untrained/naive consumer subjects to compare multiple test stimuli against a fixed reference, such as a company's gold standard or a stimulus familiar to the consumer. Such tests are used for various objectives, including reformulation and cost reduction. Yet, studies on relative discrimination power and efficiency have been limited to experimental designs with a fixed pair of stimuli and method comparisons based on the same numbers of tests. In the present study, two reminder methods, A-Not A with Reminder (A-Not AR) and 2-AFC with Reminder (2-AFCR), were investigated as potentially better methods for experimental designs including comparisons of multiple pairs of stimuli for consumer discrimination. 2-AFCR is procedurally equivalent to a constant-reference duo-trio test with the reference presented first (DTF) and thus this test is referred to as the constant-ref. DTF/2-AFCR test in this paper. The practical efficiency of these two reminder methods, attributed to their effective stimulus configurations in replicated tests (i.e. using a fixed reference and lower number of different stimuli required in a test), was tested in comparison with the two most commonly used balanced reference classification methods, the triangle test and the unspecified tetrad test, by equalizing the number of stimuli required for the different methods. Namely the relative operational discrimination power was studied based on the same number of stimuli rather than the same number of tests. 180 naive consumers performed a set of 12 replicated triangle tests and, based on the results, were divided into one of three equally-performing groups. A related-samples design was implemented for comparison between the triangle and the other three methods. An independent-samples design was implemented across the three groups to compare the A-Not AR, constant-ref. DTF/2-AFCR, and unspecified tetrad methods. Statistical ratio comparisons of d' estimates obtained from different methods revealed that discrimination performance in the reminder methods was better than in both the tetrad and triangle methods. No discrimination difference was found between the triangle and tetrad tests having all possible test sequences, although the triangle test considering only the optimal test sequences, which were the same as those in the constant-ref. DTF/2-AFCR, resulted in superior discrimination than the tetrad test. Collectively, these results suggest that when assessing the discriminability of multiple stimuli from a fixed reference, the reminder scheme is the superior research design. (C) 2015 Elsevier Ltd. All rights reserved.</P>
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Stocks, M.,Shepherd, D.,Lee, H.S.,van Hout, D.,Hautus, M.J. Published on behalf of the Canadian Institute of F 2017 Food Research International Vol.97 No.-
<P>Discrimination tests are used in food companies to quantify small differences between products. Within the diversity of methods available, some are quicker to conduct, whereas others are more sensitive or statistically powerful. One class of methods includes the reminder tasks in which the reference product is given before tasting the actual test stimuli. During the task, such a 'reminder' can be compared directly to each test stimulus, or alternatively, only serve to prime the memory of the judge without being taken into account in decision-making. Previous research with trained judges provided evidence for the latter process while research with untrained consumers has provided some evidence for the former process. Two studies were conducted with untrained consumers using the A Not-AR and 2-AFCR reminder tasks. Objectives were to determine the decision strategies used in, and the relative sensitivity of the tasks. In addition, the use of an 'authenticity test' was explored to see if this has a positive effect on test performance. In the first study, mayonnaise and ice tea with small stimulus differences (d' < 1) were used in A Not-AR and 2-AFCR. Results were compared to those from A Not-A and 2 AFC tasks, with and without an authenticity test. It was difficult to draw clear conclusions on the decision strategy used, though the use of an authenticity test increased the sensitivity for these small differences, as it improved the performance of 6 out of 8 tests. In the second study, ice teas with larger stimulus differences (at two levels) were tested using the A Not -AR and 2-AFCR tasks, in comparison to the same-different task. The results showed that consumers use the less optimal strategies and that the authenticity test decreases performance, which is contradictory to the results of the first study. It seems that for very small stimulus differences the authenticity test can improve performance, but with larger differences the authenticity test decreases performance; it seems to confuse the judges.</P>
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