James McNulty, of Florida State University, did a study finding that newlyweds subconsciously know whether or not their marriage will fail.

The study was done using a photo of the spouse with both positive and negative word to get a so called automatic attitude.

The researchers would show a picture for a third of a second: just long enough to realize who the photo was, but not enough time to over analyze the photo. Then, participants in the study would say both a positive and negative word. The spouse had two buttons they could push: one positive and one negative. Their response led to their automatic attitude.

The study tested 135 couples, with 12 couples having divorced after the honeymoon phase wore off.