How Old Is Your Soul, Really?

Personality moves, and it moves in a direction

The folk assumption is that character sets like plaster in your twenties. Longitudinal research says otherwise, and it says so consistently. In 2006 Brent Roberts, Kate Walton and Wolfgang Viechtbauer pooled 92 longitudinal samples covering the whole adult lifespan and looked at how average trait scores shifted with age. The pattern they found is now called the maturity principle.

People tend to grow more conscientious and more emotionally stable, with the sharpest movement between roughly twenty and forty. Agreeableness climbs too, though later, often into middle and older age. Assertiveness rises in early adulthood. Openness rises through adolescence and drifts gently down again in later decades. In other words, the average person becomes steadier, warmer and less easily rattled with each passing decade, which is not the story most of us tell about getting older.

Two different questions about changing

When someone asks whether people really change, they are usually running together two questions that have different answers. The first is about rank order: if you were the most organised person in your school year, are you still near the top thirty years later? Broadly yes. Relative standing is remarkably persistent, and it becomes more persistent as people age.

The second question is about mean levels, and here the answer is a clear yes. Everyone can drift upward on conscientiousness while keeping their position relative to everyone else, the way a whole class can improve without changing who sits at the front. Both facts are true at once, which is why the same body of evidence gets quoted to prove that people never change and that they always do.

One likely explanation is unglamorous. Taking on work, partners, dependants and mortgages seems to pull behaviour towards reliability, and the trait scores follow. Researchers call it social investment, and it fits the timing of the shifts rather well.

So how old is your soul, then

Not a question psychology can answer, and this quiz is not attempting to. Seven items about weekends and bedtimes sort you into one of four brackets written to be recognisable and flattering. There is no scale here with published reliability, no evidence the result would repeat next month, nothing to compare your answers against beyond the author's judgement.

The genuinely interesting finding sitting behind the joke is that the version of you answering these questions is not the finished article. Ask again at forty, at sixty, and the honest answers are likely to have shifted in a direction the research can already predict.