Reading focus
Syllabus: What Can Individual Differences Predict?
Compare mortality, divorce, and occupational attainment, attending to differences in measurement, study selection, and adjustment across predictors.
Why you’re reading it. Give personality and cognitive ability a place in a broader account of consequential differences, while examining how the comparison is constructed.
A question to consider. Would similar average associations for personality and socioeconomic status show that both add equally useful information to the programme’s existing records? What joint comparison is missing?
Why this reading
The paper that answered the question "do personality traits matter?" with a comparison rather than an assertion. Roberts and colleagues gather prospective longitudinal studies and compare how well personality traits, socioeconomic status, and cognitive ability predict three outcomes that few would dispute matter: mortality, divorce, and occupational attainment. Traits predict about as well as the other two. The comparison illustrates individual-differences reasoning: what it means to say that a measured difference between people is consequential, and how such claims are made comparable.
Before you read
The Big Five describe broad dimensions of personality: openness to experience, conscientiousness, extraversion, agreeableness and neuroticism. They describe variation in characteristic thoughts, feelings and behavior, rather than five types of people. A correlation describes the direction and strength of an association. Here, ask what an association's size means for the outcome and period being studied, rather than treating the word “small” as a conclusion about its importance.
Notice that the evidence is prospective and observational. Traits are measured first and outcomes later, but no one is assigned a personality at random.
Read for
- The decision to compare traits against SES and cognitive ability, and why that comparison is more persuasive than reporting trait correlations alone.
- How the authors argue that correlations of the size they find are practically important, and whether the argument is convincing.
- The mechanisms proposed for how traits could influence life outcomes over decades. Which are tested here, and which are conjecture?
- The limits the authors acknowledge: measurement quality varies across predictors, and prediction is not explanation.
Consider afterwards
- A trait predicts an outcome thirty years later. List three different causal stories that could produce that association, only one of which runs from the trait to the outcome.
- If personality matters as much as socioeconomic status, should policy respond to it in the same way? What would that require knowing?
Editorial context
The comparison concerns predictive associations assembled across studies; it does not establish that personality, socioeconomic status, and cognitive ability have interchangeable causal effects. Differences in measurement reliability, predictor breadth, adjustment, and follow-up complicate comparisons. Return to the paper's own inclusion decisions and effect-size conversions when assessing its conclusion. The open author manuscript provides the methods behind the headline comparison.