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An experiment on taste sensory analysis was conducted to explore the effects of manipulating signal intensity and response incentives on sensitivity and decision processes when evaluating basic tastes under high ecological validity conditions. Salt concentration (0.07%, 0.1% or 0.75%) and payoff matrices that were intended to produce lenient, conservative, or neutral response strategies were manipulated in a full factorial between-subjects design. Salt concentration only affected the sensory process (sensory index A’) while payoffs only affected the decision process (decision index B’ D ). The effect of the payoff manipulation on the decision index was symmetrical for lenient and conservative induced response strategies, though less extreme than the values predicted by Signal Detection Theory for an optimal performance under unbalanced payoffs. [ABSTRACT FROM AUTHOR]

Abstract: An experiment evaluated a Signal Detection Theory (SDT) approach to olive oil tasting research within laboratory conditions akin to ecological tasting situations. Participants confronted a tasting situation in which olive oil concentration (0.4%, 0.8% or 1.6%) and instructions (lenient or conservative) were manipulated in a full factorial between-subjects design. Results were analyzed using a variety of measures of sensitivity and bias, both parametric and non-parametric, as well as robust statistics. Olive oil concentration only affected sensory processes while instructions only affected decision processes. Non-parametric indices of sensitivity A′ and bias B′D, and robust analysis of variance were, both conceptually and methodologically, the most suitable for separately measuring sensory and decision processes in the context of olive oil tasting. [Copyright &y& Elsevier]

Abstract: Training schedules including progressive increments of difficulty lead to a better performance on a harder version of a discrimination task than non-progressive schedules that only include the hardest level of difficulty. A detection task in which participants had to detect whether the samples that they tasted contained a small amount of olive oil was used to test the relevance of this phenomenon in an olive oil tasting context. Two groups of participants received three training sessions with this task before receiving a final test of performance. In group hard-to-hard, olive oil concentration was kept low and constant throughout sessions and testing. In group easy-to-hard, olive oil concentration was high in the first training session. Olive oil concentration was progressively decreased across sessions, reaching the same level of the hard-to-hard group at the time of testing. Results showed better ability for detecting olive oil when participants were trained with progressively lower concentrations of olive oil than when the training program involved only the lowest (most difficult) one. Progressive training led participants to show a conservative bias that did not appear when training was only conducted with the most difficult discrimination. [Copyright &y& Elsevier]

Abstract: Sensory evaluation of olive oil has been conducted by using the Classical Threshold Theory perspective. This approach does not allow the separation of purely sensory processes from other factors that may affect performance such as tasters’ cognitive biases. Two experiments were conducted with the goal of developing a task that, using the logic of Signal Detection Theory (SDT), would allow sensory and decision processes to be separately assessed within an olive oil tasting task, overcoming the shortcomings of the traditional Classical Threshold Theory approach. Experiment 1a used classic psychophysics theory to establish the olive oil concentrations that were used later in Experiment 1b. Experiment 1b presents a taste task based on SDT (by using signal and noise stimuli) that allowed establishing ROC curves and the separate calculation of sensory and decision indexes. Non-parametric detection and sensory indexes, and robust analyses of variance are proposed to overcome the problems associated with the use of a limited number of trials involved. The advantages of the SDT approach in olive oil tasting are discussed. [Copyright &y& Elsevier]