This study tested the prediction that preferences induced by hidden factors would be justified and even accelerated by other factors that seem to be plausible determinants as causes but, in fact, do not have any influence on the preferences. Participants were repeatedly exposed to a variety of product logos of detergents and then asked to choose one from a pair of detergents with different logos. For half of the participants, information on product quality was available at choice; for the other half, only logos were available. The participants showed a tendency to prefer detergents with the logos that were more frequently exhibited, and this tendency was stronger when information was available about the product quality. The participants seemed to believe that they based their decisions on the relative superiority of quality between the pairs as well as their logos. Provided with convincing, but incorrect, reasons to make a choice, the participants were encouraged to select the detergents whose attractiveness had actually been manipulated by exposing the participants to their logos.