Predecisional distortion of product information

Two consumer choice experiments reveal distortion of product information. When relatively equivocal information about two hypothetical brands is acquired one attribute at a time, the evaluation of a subsequent attribute is distorted to support the brand that emerges as the leader. This distortion in favor of the leading brand occurs in the absence of any prior brand preference and even when no choice is required. In the latter case, brand preference is formed spontaneously and privately. The magnitude of this predecisional information distortion is roughly double the well-known postdecisional distortion due to cognitive dissonance. A second study shows that, even when the product information is diagnostic, substantial distortion remains. Furthermore, when the diagnostic information leads to a reversal of the currently preferred brand, distortion reappears in support of the new leading brand. The implications of predecisional distortion of product information are discussed for the presentation order of brands, the presentation format of product attributes, and the potential bias in preference assessment techniques, such as conjoint measurement, that rely on pairwise choices.