Déjà vu is a memory phenomenon widely experienced by the general public and is often cited in the popular literature. While the experience was described in the scientific literature as early as the mid-1800s, researchers used a variety of different terms to describe the experience (e.g., paramnesia) until the middle of the twentieth century. A standard definition of déjà vu used today was provided by Neppe (1983, p. 3): "any subjectively inappropriate impression of familiarity of a present experience with an undefined past."

Survey research indicates that between half to two-thirds of individuals have had a déjà vu experience, although this estimate varies considerably (30 to 97 percent) across three dozen investigations. Of those who experience déjà vu, nearly all have had more than one, and most experience one or more each year. A déjà vu experience...