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Determining critical attributes associated with consumer perceived benefit and choice is essential for the fast moving consumer goods industry. The goals of the present study were to develop a lexicon specific to usage process for kitchen cleansers using a novel consumer test and to test usage stage-dependency of the lexicon. Holistic usage process of kitchen cleansers was classified into purchase moment, during use and completion point. For a series of projective interviews, a semantic/language library, a collection of attributes relevant to kitchen cleansers was used as response options. Ethnographic observations/interviews were also incorporated into the consumer test to evoke consumers' natural usage process. Comparisons of the developed lexicon revealed differences of consumers' evaluation processes across different usage stages. At the purchase moment, attributes associated with Convenience and Functionality categories were found to be more important, whereas at completion point, attributes associated with Sensory Quality and Sentimental Consequence were more important. [ABSTRACT FROM AUTHOR]

A new paradigm of the duo-trio difference-preference (DT-Preference) test was developed as alternatives to the paired-preference test with a no preference option, to correct the overestimation of preference responses. Triadic sample presentation in a preference test elicits odd sample bias, i.e., preferring the sample selected as the same as the reference. In the two replicated DT-Preference test applied for fermented milk product testing using 208 consumers, this psychological bias in preference responses was apparent in the first test. This bias referred to as the tried first reference bias was eliminated by treating those responses that changed depending on which reference was presented as though no preference had been expressed, leading to more reliable sample preferences, meaningful to consumers. The perceptual discriminability in DT-Preference tests was not decreased in comparison to the sole difference tests, while when the preferred sample was used as a reference, the discrimination increased. Practical Applications Consumer acceptance mainly determines the sensory quality of products. Paired-preference test with a no preference option is a broadly used sensory acceptance test method. Yet this preference test method suffers from preference bias caused by the order of sample presentation and/or hidden demand characteristic of the preference test. Such a psychological bias can generate preference responses toward either product presented in a pair for slight or no differences in sample preference, which is not meaningful for consumer behavior. The new paradigm of the duo-trio difference-preference test with a perceptual reference introduced in this article uses another type of psychological bias - odd sample bias - as a means to regulate such biased preferences expressed in a predictable manner. Using this approach, the validity and reliability of preference data analysis can be improved by finding more accurate response proportions of two-way preference responses versus no preference responses. [ABSTRACT FROM AUTHOR]

For the paired difference or preference test applied to consumer research, the 2-Alternative Choice (2-AC) method that allows a "no difference" or "no preference" option is more suitable. For this method, using both test and placebo pairs is seful for estimating the degree of response bias among the consumers using the test and accurately estimating the degree of difference or preference between the test pairs. This paper proposes a Thurstonian model for the 2-AC for both test pairs and placebo pairs in a test method. Maximum likelihood estimations are used for the parameters: d', a perceived distance of difference or preference, and τ, a criterion and a decision parameter. Three methods are used for estimations of the covariance matrix for the parameter estimators: (1) using the built-in functions in the S-Plus and R packages, which are based on maximum likelihood and observed Fisher information; (2) the delta method, which is based on the Taylor series approximation; and (3) the bootstrap method, which is computer-intensive with resampling. Statistical tests are discussed for d' and vectors of responses for test pairs and placebo pairs in both a monadic design and a paired design. R/S-Plus codes are developed and provided for the calculations. [ABSTRACT FROM AUTHOR]

Psychometric functions for discrimination tests, which connect probabilities of correct response, pc, with Thurstonian discriminal distances, d′, are of theoretical and practical significance. This paper uses a computer-intensive approach to produce simulation-derived psychometric functions for the ' M + N' test, which is a generalization and can be considered as a framework of many forced-choice methods. The paper demonstrates and describes chance probabilities in different situations for the ' M + N' test. The paper compares the performances of the specified and unspecified ' M + N' test with the M = N test. The paper provides novel tables for pc and d′ for four specific versions of the ' M + N' test: the specified 'two-out-of-five' test (i.e., the ' M + N' test with M = 3 and N = 2); the unspecified 'one-out-of-four' test (i.e., the ' M + N' test with M = 3 and N = 1); the specified and unspecified octad tests (i.e., the ' M + N' test with M = N = 4). The corresponding B values, for calculation of the variances of d' for the tests, are also provided. The concept and practice of pseudo-correct response, i.e., forgiveness introduced by Ennis, are discussed and generalized. Practical Applications Considering the constraints imposed by the products and the circumstances of the business objective, different forms of various difference test method might be selected as the most suitable design. The proposed Thurstonian modeling approach using a simulation-derived psychometric function makes it possible to drive psychometric functions for any one of the more than 40 different versions of the ' M + N' test. This paper shows that a simulation-derived psychometric function is compatible with an exact psychometric function. R/ S-Plus codes for the simulation-derived psychometric functions are also developed and provided. Using this technique, various versions of commonly used sensory difference test methods, including the 2- AFC, triangle and tetrad, can be compared with many more versions of difference test methods. In addition, using the supplied R/ S-Plus codes, the Thurstonian sensory difference measure, d′, can be computed easily and quickly for various forms of the ' M + N' test. [ABSTRACT FROM AUTHOR]

The A- Not A with reminder ( A- Not AR) is a relatively new method in the sensory literature. This paper derives and demonstrates the function illustrating the relationship between the area under the receiver operating characteristic ( ROC) curve and d′ for the A- Not AR with the differencing strategy. This function shows that the area under an ROC curve for the A- Not AR is equal to the maximum proportion of correct responses in an A- Not A. This theoretic function can be used to estimate d′ and its variance from the ratings of the A- Not AR. A simulation study shows that the nonparametric estimation based on this function is close to those obtained by using the maximum likelihood estimation. The estimation of the variance of d′ based on the delta method is close to that obtained by using the bootstrap method. R codes are provided for the estimations of d′ and its variance as well as simulations. Practical Applications The A- Not AR is a variation of the conventional A- Not A method, which is used in the sensory field for discrimination testing. This method is particularly useful when it is difficult to have an adequate familiarization procedure for the test samples for panelists before a test. This approach also offers the potential for applying such a method to problems like hedonic, purchase intent, and consumer concept measures in addition to other measures in the sensory and consumer science field. This paper provides a new nonparametric method and R codes for estimating d′ and its variance from the ratings of the A- Not AR. [ABSTRACT FROM AUTHOR]

Ratings are widely and frequently used in sensory analysis. However, ratings from different methods cannot be treated equivalently because they represent different types of data generated from different cognitive mechanisms. Ignoring this fact may lead to misleading conclusions about true sensory difference or treatment effects obtained from the ratings data analysis. The receiver operating characteristic ( ROC) curve in signal detection theory is used in this paper to model the ratings of the A- Not A and the same-different methods. This paper comprehensively discusses statistical analysis of the ROC curves for the methods, including presentations of the ROC curve functions, estimations of d′s and their variances, goodness-of-fit tests, difference and similarity tests, testing powers and sample sizes, etc. The paper also discusses alternative indices of sensory difference derived from the ROC curve, including the R-index and Gini index. It is appealing to rethink the significance of the R-index, not only as a powerful test statistic but also as a useful sensory measure. R functions are provided for implementing all the analyses discussed in the paper. Practical Applications This paper provides a variety of approaches and R functions for statistical analysis for the ratings of the A- Not A, and the ratings of the same-different methods. The measures of d′s and other indices, which are method-independent measures of sensory differences and treatment effects, can be estimated from different types of ratings data. [ABSTRACT FROM AUTHOR]

ABSTRACT 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. [ABSTRACT FROM AUTHOR]

Besides responses to the target pair of stimuli being tested in a paired preference test, comparison with responses to a putatively identical "placebo" pair can be used for a test of significance, to determine whether the response frequencies elicited by the target pair are different from those that would be obtained had there been no preference. Yet, preference responses elicited by the placebo pair can also be used as a way of identifying consumers who bias avoided the "No preference" option and thus generated biased response. Such consumers can then be eliminated. Yet, using this approach greatly reduces the sample size. However, using some response options associated with purchase intent rather than liking can reduce the number of consumers that are eliminated. This was confirmed for potato chip, milk and orange juice stimuli. From psychology, the concepts of operational preference and types of response bias appropriate to preference testing were introduced and discussed. PRACTICAL APPLICATIONS: The measurement of preference and acceptance of foods is important for product development and decisions regarding the launching of new products into the market. The paired preference test has some issues associated with its design and analysis, and these must be considered if preference tests are to give valid and reliable data. One of the problems is that the majority of consumers tend to report preferences even when the stimuli are putatively identical; here, a "No preference" response would seem more appropriate. Such consumers would seem to be reacting to the extraneous conditions of the preference test rather than the sensory characteristics of the putatively identical stimuli under consideration. Such responses could be termed "biased response." Yet, the consumers' responses to the target (different) stimuli under consideration could be trusted more if the consumers had shown that they did not have this tendency to give "biased responses." They would show this by selecting a "No preference" response to putatively identical stimuli. This paper shows that the tendency to give "biased response" can be reduced by manipulating the wording of the preference question. This does not furnish a complete solution to the problem but it indicates one possible step toward solution and adds valuable information to the body of knowledge that is being built with a view avoiding the difficulties associated with preference testing. [ABSTRACT FROM AUTHOR]

The four-alternative forced choice (4-AFC) is one of a family of m-AFC tests used in Psychology. Based on a detection-theoretic model, for a given d′ it is slightly more powerful than the 3-AFC and 2-AFC. Although its potential use in sensory food science is limited, there are occasions when it will be used. Accordingly, tables of d′ values for given proportions of correct responses (pc) along with corresponding values of B, for computing variances, are given in this paper. Power comparisons are also made between 2-AFC, 3-AFC and 4-AFC tests. PRACTICAL APPLICATIONS For sensory difference testing, the choice of test will depend on several factors such as statistical power as well as various physiological and cognitive effects. Because of the wide variation in the sensory effects that food and personal product stimuli can have on judges, it is important to have a wide variety of test methods available. Therefore, even less common tests need to be considered. The 4-AFC can be used on occasions and it is certainly suitable for visual judgments. Accordingly, for this method, it is appropriate to have tables of d′ and B for computing variances. [ABSTRACT FROM AUTHOR]

The literature includes many studies that use the shape of the receiver operating characteristic (ROC) curve derived from the same–different test to ascertain the decision strategy used by the judge: a symmetrical ROC curve indicates a β -decision strategy, and an asymmetrical ROC curve indicates a τ -decision strategy. These studies have not considered the effect that breaches of the assumptions that underlie the standard same–different model would have on inferences drawn from the shape of the ROC curve. Three such assumptions are investigated: the equal-variance assumption; the assumption of no stimulus order effects; and the assumption that the discriminability of the two stimuli is the same when presented first or second in the test sequence. Simulations indicate that the shape of the ROC curve is very tolerant of the breach of these assumptions. Consequently, inferences about the decision strategy used by a judge are fairly robust, and confidence in published results is upheld. PRACTICAL APPLICATIONS The same–different test is frequently used to determine the decision strategy adopted by judges. There are several assumptions made about the same–different test that may, if they were breached, undermine this test's ability to indicate the judge's decision strategy. The simulations conducted in this research indicate that the shape of the same–different ROC curve is very robust to breaches of these assumptions. Consequently, food scientists can maintain their confidence in the inferences made in the research already published on this topic, and in their own future research and development of sensory testing methods. [ABSTRACT FROM AUTHOR]

Although the infusing condition of green tea is critical in determining green tea quality, the green tea industries lack a validated standardized tea preparation procedure. The objectives were (1) to develop an effective sample preparation and presentation procedure to conduct an objective sensory analysis; and (2) to elucidate the effects of green tea types and infusing conditions on the sensory characteristics of green tea. The optimum infusing times for green tea at two temperatures (60 and 80C) were determined using the just-about-right scale evaluated by consumers. Then, a descriptive analysis was conducted. The panelists developed 16 descriptors, and determined the reference samples and the tasting procedure. The optimum infusing time–temperature combinations are approximately 3 min at 60C or 1 min at 80C. The intensity of fermented-like flavor increased, but cut grass and floral flavor decreased with the lower-graded tea leaf. Samples infused at 60C–3 min were sweeter but less bitter than samples at 80C–1 min. PRACTICAL APPLICATIONS The sample preparation method and evaluating conditions developed in this study have been validated using both analytical and consumer studies. The protocols showed to be powerful in discriminating the sensory characteristics between the samples when conducting objective sensory analyses. The sensory lexicons and standards established should be useful to researchers and product developers who are working with flavors of green tea. Additionally, the sample preparation method and evaluation procedure introduced in this study are relatively straightforward, thus, making it possible for the general sensory scientist group to use an effective standardized method when conducting objective sensory analyses of green tea. [ABSTRACT FROM AUTHOR]

Preference tests were performed for varieties of potato chips, orange juices and chocolate chip cookies using three response protocols: the traditional paired preference test with the “no preference” option, a 9-point hedonic scale and a 6-point hybrid hedonic/purchase intent scale. The different stimuli to be assessed were presented in pairs, but putatively identical stimuli were also presented as a “placebo” pair. Performance on the placebo pair with identical stimuli provided a measure of the hidden demand characteristics of the test protocol. The presentation of the different pairs provided a measure of preference accompanied by such hidden demand effects. Comparison between the two allowed a better measure of preference per se. The order of presentation of the identical and different pairs did show occasional slight evidence of contrast effects. For the placebo “identical” pairs, a majority of consumers reported false preferences. Liking questions with the hedonic and hybrid scales elicited fewer false preferences than preference questions with the paired preference protocol. Yet, the effects tended to be slight. The 6-point hedonic/purchase intent scale exhibited the fewest false preferences in the placebo condition, and this was because of its fewer categories rather than any cognitive strategy change elicited by its different labels. PRACTICAL APPLICATIONS A problem with paired preference testing is the tendency of consumers to give false preferences, which produces the seriously misleadingoverestimation of the proportion of consumers who have preferences for one or other of the products being assessed. The placebo condition is an important control for alleviating this problem. The statistical analysis can be improved by finding a protocol that maximizes the proportion of “no preference” responses in the placebo condition. The key finding here is that using hedonic or purchase intent questions rather than preference questions may possibly provide a way of achieving this aim. [ABSTRACT FROM AUTHOR]

ABSTRACT Coffee served at temperatures recommended by the hospitality and food literatures for brewing and holding are above thermal pain and damage thresholds. Yet, consumers do not report pain or damage on drinking coffee at such temperatures. To investigate this discrepancy, the temperature of hot coffee before and during sipping was investigated for 18 subjects. Coffee temperature was continuously monitored by thermocouples in the cup, in the coffee bolus in the oral cavity and on the surface of the tongue. There was minimal cooling as the coffee entered the mouth from the cup, yet the coffee temperature was still above threshold for inducing burn damage. It is hypothesized that during drinking, the bolus of hot coffee is not held in the mouth long enough to heat the epithelial surfaces sufficiently to cause pain or tissue damage. [ABSTRACT FROM AUTHOR]

ABSTRACT Stimulus frequency context effects were noted for stimuli with positive, negative and no skew, using aqueous NaCl stimuli of different concentrations as a model system and orange juice stimuli with added amounts of sucrose as a beverage system. The hypothesis that analysis by signal detection Δm values, rather than individually rated intensity values, would result in the absence of the context effect, was not confirmed. [ABSTRACT FROM AUTHOR]