The doctrine of informed consent rests on empirical claims. This is true particularly of what commentators have characterized as the "strong" model of informed consent. This model assumes that if adequate information is given to a competent individual, understanding will result and, permitted to make a voluntary decision, the individual will make a rational decision. However, the "therapeutic misconception" posits that individuals may confuse the goals of research with those of treatment and may make decisions that do not rest on adequate understanding. This article reviews research suggesting that this may in fact be true, and concludes that, as a result, traditional notions of informed consent may not yield results consistent with the assumptions on which the doctrine of informed consent rests.