Across All Cultures, Dreams Affect Behavior

They may rarely predict future events, but most people believe they are meaningful.

"Psychologists' interpretations of the meaning of dreams vary widely," lead author Carey Morewedge, an assistant professor at Carnegie Mellon University, said in an American Psychological Association news release. "But our research shows that people believe their dreams provide meaningful insight into themselves and their world."

For example, 149 university students in the United States, India and South Korea in one survey largely agreed that hidden truths present themselves in their dreams, a theory a nationally representative sample of Americans also supports.

Dreams also affect how people act when they awake, another study found. A survey of Boston train commuters found that when they dreamed of a plane crash the night before a scheduled air trip, they would be more likely to change their travel plans than if they had had a dream about an increased terrorist threat or consciously thought about their plane crashing. Dreaming about a plane crash also caused them as much anxiety as would a plane disaster actually occurring on their planned route shortly before their trip.

While most people said dreams rarely predict future events, they still found them meaningful, even if they were uneventful or plain bizarre, Morewedge said.

Not all dreams are equal, though. When asked to recall a dream about a person they knew, 270 Americans taking an online survey gave more significance to pleasant dreams about someone they liked than bad dreams about someone they didn't like.

"In other words, people attribute meaning to dreams when it corresponds with their pre-existing beliefs and desires," Morewedge said.