'Envious' Reigns As Most Common Personality Type

The majority of people fall into one of four personality categories, a recent study from Spain finds. In the study, researchers categorized about 540 people as belonging to four personality types — optimistic, pessimistic, trusting and envious — by asking them to play a series of games in pairs. People who were found to have an optimistic personality included those who believe that cooperating with their partners would lead to positive choices for them both, according to the study.