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Abstract: The objective of this research was twofold: first, the performance of the tetrad protocol was compared to that of the triangle test under conditions that could possibly lower its sensitivity, consequently resulting in the loss of its theoretical power advantage. Second, the same samples were compared with a preference test to investigate whether a no difference conclusion obtained with a discrimination test would consistently result in a non-significant preference (consumer relevance). The investigation involved sensory differences that could be deemed small (d′ values less than 1.0) as well as the comparison of resampling vs. no resampling conditions. 456 consumers performed tests using apple and orange juices for which slight sensory differences were created through dilution. In all conditions, the tetrad always exhibited a greater number of correct answers than the triangle, confirming its greater statistical power. Therefore, it was concluded that even for small sensory differences, and in conditions where sensory fatigue could play a greater role (resampling allowed), the tetrad test sill appears like a good alternative to the triangle. Also, the theoretical increase in performance predicted when allowing sample resampling was confirmed. For the preference study, the same stimuli were evaluated by 208 subjects. Consumer relevance was defined as a significant result between two products in a preference test (assuming no population segmentation). Such significant preferences were found for three out of the four conditions, including the one with the smallest difference for which a significant result had not been found with either the tetrad or triangle. The non-significant preference in the fourth condition was attributed to segmentation in the population. Therefore, this investigation confirmed further that the tetrad test is a viable alternative to the triangle test, as it exhibits a greater statistical power even in conditions that could potentially affect it negatively. Also, it was shown that a non-significant sensory difference can still result in a significant preference test, outlining the necessity to go beyond the simple use of a ‘more powerful’ discrimination test when making decisions and to define the actual consumer relevance of an underlying sensory difference. [Copyright &y& Elsevier]

Abstract: Paired preference tests of liking require consumers to specify which of two foods are preferred or whether there is no preference. For ‘Buying’ preference tests, consumers specify which of two foods they are more likely to buy or whether they might buy either or neither. For ‘Choosing’ preference tests, consumers specify which of two foods they are more likely to choose when offered both, or whether they might choose both or neither. The first test is designed to predict greater degrees of liking, the second to predict buying behavior and the third to predict choice behavior. Yet, test results may not necessarily predict ‘real life’ behavior once consumers have left the testing situation; the ‘test’ preferences may not be ‘operational’. To validate the predictive ability of such tests, consumer behavior should be monitored for several months. Another approach is to allow consumers to take away some of the foods used in the test and observe what they take away. Consumers of potato chips were required to taste chips whose flavor and appearance were obviously different. A first group (N =107) were given ‘Liking’, ‘Buying’ and ‘Choosing’ preference tests for two palatable types of chip. After the test, out of sight of the experimenter, consumers were presented with two rows of plain plastic ‘snack’ bags, filled with the chips used in the test. They could take away either two bags of the same type of chip (a ‘Take Away’ preference) or one of each type (no ‘Take Away’ preference) or take neither (rejection). They were also subtly questioned regarding whether they were going to consume the chips themselves or were going to share them with friends. A second group (N =103) repeated the experiment. However, for these consumers, one type of chip was unpalatable. In general, ‘Buying’ preferences corresponded more to ‘Take Away’ preferences while ‘Liking’ and ‘Choosing’ preferences showed little correspondence. For the palatable chips, the preferences were spread more evenly than for the case where one type of chip was undesirable. In this latter case, approximately 50% of consumers were consistent over all tests in choosing the palatable chip. This might suggest operational preferences. ‘Take Away’ preferences suggested low predictability for paired preference tests of liking, choosing and buying. ‘Take Away’ preferences are not a substitute for monitoring consumer behavior for several months but they are a step in the right direction. [Copyright &y& Elsevier]

Abstract: Paired preference tests of liking require consumers to specify which of two foods are preferred or whether there is no preference. For ‘Buying’ preference tests, consumers specify which of two foods they are more likely to buy or whether there is no operational difference in likelihood to buy. The former test is designed to predict choice behaviour, the latter, buying behaviour. To validate the predictive ability of such tests, consumer choice and buying behaviour should be observed for several months. Another approach is to allow consumers to take away some of the foods used in the test and observe what they take. Consumers of potato chips were required to taste chips whose flavour and appearance were obviously different. A first group (N =109) were given a traditional paired preference test of liking. A second group (N =108) were given a preference test of buying. A third group (N =101) were given both tests. After the test, out of sight of the experimenter, consumers were presented with two rows of plain plastic ‘snack’ bags, filled with the chips used in the test. They could take away either two bags of the same type of chip (a ‘Take Away’ preference) or one of each type (no ‘Take Away’ preference) or take neither (rejection). ‘Liking’ preferences predicted what was taken away for only 48% of consumers for the first group and 45% (third group). For ‘Buying’ preferences, the correspondence was 56% (second group) and 60% (third group). Using buying tests separately or together with liking produced some differences. More reliably, approximately 60% of consumers in all groups chose one bag of each. ‘Take Away’ preferences suggested low predictability for paired preference tests of liking and buying. ‘Take Away’ preferences are not a substitute for following a consumer for several months but they are a step in the right direction. [ABSTRACT FROM AUTHOR]

An unspecified number of consumers who used a 9-point hedonic scale were frustrated because they could not express preferences for products with the same ratings. Accordingly, consumers were required to rate samples of yogurt on a 9-point structured hedonic scale. Consumers were able to express preference judgments because the testing was performed one-on-one with the experimenter. Thus, it was possible to determine the proportion of consumers who had given the same hedonic response to yogurts but still had preferences for one or other of the stimuli. Further testing, which included a pair of identical yogurts among the stimuli, allowed the proportion of preference and no preference responses elicited by identical stimuli to be determined in this context. Such data are useful as a control condition in preference testing, to assess the proportion of false preferences induced by the experimental conditions. PRACTICAL APPLICATIONS Consumer liking for various products is typically measured using the 9-point structured hedonic scale. Sometimes, consumers will give the same score to two products yet prefer one to the other. Such preferences are not recorded if the consumer is isolated from the experimenter and has no means of reporting them. However, the situation is easily rectified if the experimenter interacts one-on-one with the consumer. Sometimes, false preferences can be obtained from a hedonic scale. This tendency can be monitored by including identical stimuli in the measurements. The present study investigated the extent of such problems so that methods could be devised to address the problem. [ABSTRACT FROM AUTHOR]

For the triangle, duo-trio, same-different and 2-AFC methods, using a model system, mean d′ values for the same subjects, discriminating between the same taste stimuli, were not significantly different. This confirmed the postulated cognitive strategies used for these methods in their respective Thurstonian/signal detection models. Introduction of perceptual variance as a result of the effects of sequences of tasting within a test, forgetting stimulus perceptions and τ- criterion variation resulted in the 2-AFC eliciting a significantly higher d′ than the other three methods. Yet, after a warm-up procedure, which not only significantly increased values of d′ for all methods but also aligned subjects' τ- criteria, the same-different test had a d′ comparable to that of the 2-AFC, while both d′ values were significantly higher than those of the triangle and duo-trio. This suggested that effects of memory were more important those of sequence of tasting. [ABSTRACT FROM AUTHOR]

Three groups, each comprising 200 consumers, performed paired preference tests between two flavors of potato chips. For one group, a “No Preference” option was allowed, while for the second group, it was not. For a third group, a “No Preference” option was allowed while the preference responses were differentiated as “Strong Preference” and “Weak Preference.” For all three groups, d′ values representing overall strength of preference did not differ significantly. [ABSTRACT FROM AUTHOR]

Abstract: The original 9-point scale, developed by the U.S. army for menu planning for their canteens, consisted of a series of nine verbal categories representing degrees of liking from ‘dislike extremely’ to ‘like extremely’. For subsequent quantitative and statistical analysis, the verbal categories are generally converted to numerical values: ‘like extremely’ as ‘9’, ‘dislike extremely’ as ‘1’. Yet, sometimes what is termed a 9-point hedonic scale is an unstructured numerical scale, labeled at the ends with ‘dislike extremely’ and ‘like extremely’. The former scale requires consumers to categorize foods according to how much they are liked or not; the latter requires the consumers to differentiate numerically between the foods in terms of the relative degree of liking for each. Foods that were placed in the same verbal category for the former scale might be given different numerical scores on the second scale. To illustrate this, consumers rated five chocolates, in a series of experiments, on these two types of 9-point scale (verbal categories only vs numbers only) and the proportion responding differently to the two scales ranged from 100% to 79%. This indicated that numerical data obtained from both types of 9-point scale were not interchangeable. It also suggested that consumers were using different cognitive strategies for verbal categories and numbers. To check that the difference was not caused by the fact that the verbal categories were bipolar and the numbers unipolar, the experiment was repeated using a bipolar number scale (–4 through 0 to +4). The same results were obtained. For comparison, a 9-point hedonic scale including both verbal categories and numbers together, was also used. The results for this scale showed a greater similarity to the version of the 9-point scale consisting only of verbal categories than the unstructured numerical version. Stimulus equalizing bias was used as a tool to make a preliminary investigation into the cognitive strategies involved for the two versions of the scale. The hypothesized relative strategy was confirmed for the unstructured numerical scale but the hypothesized absolute strategy was not confirmed for the scale using only verbal categories; the strategy appeared to have relative elements. Regardless of the precise nature of the cognitive strategies used for two versions of the scale, they do not give the same results and data obtained from each version should be compared with caution. [Copyright &y& Elsevier]

Abstract: Two experiments were performed in which untrained judges were required to perform a descriptive analysis, using a serial monadic protocol and an attribute-by-attribute protocol. They reached ‘criterion’ performance more rapidly using the attribute-by-attribute protocol, indicating that they were using a relative scaling strategy. Criterion performance required judges to rate all attributes according to the rank order of their physical strengths. Later, they reached criterion performance with the serial monadic protocol, indicating that during experimentation, they had learned to establish sufficient intensity exemplars for an absolute scaling strategy. [Copyright &y& Elsevier]