Dynamics of sensory and decision-making processes in the evaluation of extra virgin olive oil by a consumer tasting panel

This study aimed to assess whether a Signal Detection Theory-based approach could separately evaluate sensory and decision-making processes in untrained consumers replicating expert olive oil tasting conditions. In Experiment 1a, participants compared four unique non-commercial extra virgin olive oils (EVOOs) as “signals” against a commercial EVOO as “noise.” Overall, participants' sensitivity, as evaluated using Grier's A' index, varied depending on oil attributes, with participants being able to distinguish green oils from the commercial EVOO. Meanwhile, decision bias, measured using Donaldson B'D index, remained neutral, indicating that participants' evaluations were not biased in the absence of expectancy manipulations. Experiment 1b used a Double Dissociation Additive Test, manipulating sensory variables (green vs. ripe oils) and decision bias (by adjusting Signal-Noise base rates). Regardless of the induced bias, participants were able to distinguish the green fruity EVOO from the noise, but failed to differentiate the ripe EVOO from the noise. Expectations biases influenced evaluations only for ripe oils, revealing an interaction between sensory and decision-making processes. There were no significant differences in the economic valuation of the different oils in either experiment, indicating a dissonance between participants' declared preferences for the oils and their economic valuation. These findings highlight the value of methods that distinguish sensory from decision-making processes in EVOO tasting studies. • Participants' sensitivity varied by oil traits; decision criteria remained neutral. • Expectations biased ripe oil decisions, showing sensory-choice interaction. • Preference for EVOOs did not affect willingness to pay. • The study emphasizes methods that isolate sensory and decision processes in EVOO.