Paired Preference “Placebo” Tests With “Identical” Stimuli: Does Introducing Graded Preference Responses Affect the Frequency of “No Preference” Responses?

In the “placebo” control condition for paired preference testing, “identical” stimuli are presented to consumers to determine the frequency of preference and “no preference” responses induced by the hidden demand characteristics of the testing condition. As a control for bias, induced by such hidden demand characteristics, these frequencies can be compared with the actual preference frequencies of the nonidentical test stimuli to be assessed for preference. It was hypothesized that the introduction of graded preference response options might reduce the frequency of “no preference” responses in the placebo condition. Using identical yogurt stimuli with related‐sample (single‐group) and independent‐sample (multigroup) designs, this hypothesis was not confirmed. PRACTICAL APPLICATIONS The “placebo” condition in paired preference testing provides a way to control the tendency of consumers to give false preference. The statistical analysis can be improved by finding a protocol that maximizes the proportion of “no preference” responses in the placebo condition. This can be done by increasing the number of response options that imply no preference. Yet, there is sometimes a desire to increase the number of preference options by using graded responses for preference strength. Does this alter the dynamics of the ever‐important placebo condition by reducing the number of “no preference” responses? This project found that any effect was minimal.