Look at a photo of yourself as a teenager and, mistaken fashion choices aside, it’s likely you see traces of the same person with the same personality quirks as you are today. But whether or not you truly are the same person over a lifetime—and what that notion of personhood even means—is the subject of ongoing philosophical and psychology debate.
The longest personality study of all time, published in Psychology and Aging and recently highlighted by the British Psychological Society, suggests that over the course of a lifetime, just as your physical appearance changes and your cells are constantly replaced, your personality is also transformed beyond recognition.
The study begins with data from a 1950 survey of 1,208 14-year-olds in Scotland. Teachers were asked to use six questionnaires to rate the teenagers on six personality traits: self-confidence, perseverance, stability of moods, conscientiousness, originality, and desire to learn. Together, the results from these questionnaires were amalgamated into a rating for one trait, which was defined as “dependability.” More than six decades later, researchers tracked down 635 of the participants, and 174 agreed to repeat testing.