Consumers’ Beliefs about Product Benefits: The Effect of Obviously Irrelevant Product Information

When consumers try to assess the performance of a product on a key benefit, their information search often reveals both diagnostic information and irrelevant information. Although one would expect irrelevant information to have little impact on predictions of product performance, we present evidence that the irrelevant information systematically weakens consumers ’ beliefs that the product will provide the benefit. We show that this dilution effect persists after subjects have acknowledged the irrelevance of the additional information but that it does depend on whether the product information is processed with the desired benefit in mind. We conclude that consumers are selectively looking for information that suggests the product will deliver the desired benefit and that they categorize any additional evidence, be it irrelevant or disconfirming, as not confirming. As a consequence, irrelevant information weakens consumers ’ beliefs in the product’s ability to deliver the benefit. When consumers evaluate products or services, they often search for diagnostic information on specific product benefits. A natural consequence of this search for diagnostic information is exposure to obviously irrelevant information—information that consumers perceive as clearly uninformative about the desired benefit. Normatively, the presence of irrelevant information should not change consumers ’ assessment of the product’s ability to deliver the desired benefit. Yet, studies on social judgment have demonstrated that adding obviously irrelevant information to diagnostic information may lead to less extreme