It is a discussion that seems familiar. But new findings show that people who travel frequently are more likely to experience déjà vu. Political liberals report more déjà vu experiences than conservatives do. And déjà vu becomes less common as people grow older.
Most of us have experienced déjà vu, which means “already seen” in French, yet few scientists have studied it. Understanding its causes, however, promises to explain other mysteries of the brain, says Alan Brown, professor in the SMU Department of Psychology in Dedman College and a leading researcher on memory.
“The community of research psychologists is largely silent on the topic, but findings from such research could expand our understanding of routine memory functions,” Brown says.
Many explanations for the déjà vu experience have been connected to the supernatural, he says. In a new book, “The Déjà Vu Experience: Essays in Cognitive Psychology” (2004, Psychology Press), Brown surveys scientific research as well as popular notions of déjà vu from the early 19th century.
From the scientific studies, Brown has identified common facts about déjà vu. A majority of people experience déjà vu, some two-thirds of the population. The frequency of déjà vu decreases with age and is most common among people ages 15 to 25. People with higher incomes and more education have more déjà vu experiences. Déjà Vu appears to be associated with stress and fatigue. Those who travel have more déjà vu experiences. For some, déjà vu experiences appear to repeat prior dreams.
Although there are no definitive answers for what causes déjà vu, Brown offers four scientifically plausible possibilities: two cognitive processes become momentarily out of phase; a brief dysfunction in the brain, such as a seizure, or disruption in the speed of normal neuronal transmission; a memory that we forgot connects with part of the present experience; and an initial perception under distracted conditions is quickly followed by a second perception of the same thing under full attention.
Déjà vu research presents a unique challenge for Brown.
“There is a thrill of examining something that seems to be on the fringes, then pulling it into the scientific realm,” he says.
Brown, who joined the Psychology Department in 1974, is the author of four books, including “Maximizing Memory Power: Using Recall in Business” (1986, John Wiley & Sons).