Millions of Americans believe in conspiracy theories — including plenty of people who you might expect would be smart enough to know better.

Despite mountains of scientific evidence to the contrary, at least 20% of Americans still believe in a link between vaccines and autism, and at least 37% think global warming is a hoax, according to a 2015 analysis. Even more of us accept the existence of the paranormal: 42% believe in ghosts and 41% in extrasensory perception. And those numbers are stable. A 2014 study by conspiracy experts Joseph Uscinski of the University of Miami and Joseph Parent of Note Dame University surveyed 100,000 letters sent to the New York Times and the Chicago Tribune from 1890 to 2010 and found that the percentage that argued for one conspiracy theory or another had barely budged over time.

Now, a study published online in the journal Personality and Individual Differences provides new insights into why so many of us believe in things that just aren’t true: In some cases, we simply want to believe.