In a study of yearbook pictures, an e-mail invitation sent to approximately 18,000 alumni resulted in 428 people completing an online questionnaire, with 79 individuals removed due to no yearbook photos.
The remaining sample of 225 females and 124 males who graduated between 1948-2005 ranged in age from 21 to 81, 96 percent Caucasian. All photos for an individual were evaluated using a smile intensity score.
In a similar study, the researchers asked adults age 65 and older to provide photos from their youth and these photos were evaluated for smile intensity. The study subjects were asked if they had ever been in a committed relationship and divorced.
The findings, published in the journal Motivation and Emotion, indicates 11 percent of those with the biggest smiles divorced and 31 percent of the frowners had divorced.
Study leader Matthew Hertenstein, a psychologist at DePauw University in Indiana, says the current investigation demonstrates that from extremely thin slices of behavior, the divorce status of individuals may be ascertained.