Stability and Change

Personality Over Time

Mini Review

  • A trait is a difference between people in the ABCs that holds across situations and over time.
  • Stability AND Change is our core theme about time: personality is stable across time and still changes in predictable ways.
  • This deck explains how both can be true.

Learning Goals

  • Remember:
  • Explain:
    • Distinguish rank-order stability from mean-level change.
    • Distinguish score reliability from rank-order stability.
    • Describe the main ways average trait scores change as people age.
    • Explain why average trait scores tend to change over time.
  • Apply:
    • Identify rank-order stability and mean-level change in every day examples.
    • Apply the core themes of personality to stability and change.

Discussion: Are You the Same Person You Were?

  • In what ways have you changed since middle school?
  • In what ways are you still the same person?

A Person’s Change and a Group’s Change

  • Your answers describe how one person changed or stayed the same.
    • Ex: “I am calmer than I used to be.”
  • As a class, your combined answers describe how the class as a group changed or stayed the same, on average.
    • Ex: “Our class is less extroverted, on average, than it used to be.”
  • Researchers are interested in both of these questions.
    • Over time, do people keep their positions on a trait compared with one another?
    • Over time, does the average group score on a trait change?

Three People Measured Twice

Conscientiousness at 20 Conscientiousness at 40
Lorenzo 2 3
Alaya 3 4
Renee 4 5
  • Did anyone’s score change?
  • Did the group’s average change?
  • Did anyone change position?
  • Everyone rose one point and the average rose from 3 to 4. Lorenzo is still lowest, Alaya is still in the middle, and Renee is still highest.

Rank-Order Stability

  • Rank-order stability: The degree to which people keep their position compared with others on a trait over time.
    • Ex: Mari becomes more conscientious between ages 20 and 40, but she remains less conscientious than most of her peers.
    • Ex: The students who scored highest on extraversion as freshmen are mostly still the highest scorers as seniors.
  • Rank-order stability does not require anyone’s score to stay exactly the same.

Mean-Level Change

  • Mean-level change: A change over time in a group’s average score on a trait.
    • Ex: A class is, on average, more organized at graduation than it was at orientation.
    • Ex: The average neuroticism score of a group falls between ages 20 and 40.
  • The average can move while people keep their positions.
  • The average can also stay the same while people trade positions.

The Same Data Answer Two Questions

Rank-Order Stability Rises With Age (2000)

  • Roberts and DelVecchio (2000): Combined 152 studies that measured the same people’s traits twice, years apart.
    • Finding: The correlation between the two measurements was about .3 in childhood, .5 during the college years, .6 around age 30, and .7 between ages 50 and 70.
  • A higher correlation means people kept more similar positions.
  • Personality becomes more stable as people get older, but it never becomes fully fixed.

Reliability and Stability

Average Changes in the Big Five

  • Roberts, Walton, and Viechtbauer (2006): Combined 92 studies that followed the same people over time.
    • Finding: Conscientiousness and emotional stability rose most between ages 20 and 40.
    • Finding: Social dominance, one part of extraversion, also rose in young adulthood.
    • Finding: Agreeableness rose mainly later in adulthood.
    • Finding: Openness tended to fall in late adulthood.
  • NOTE: A rise in emotional stability means a fall in neuroticism.

Average Changes in the Big Five

The Maturity Principle

  • Maturity principle: The tendency for average conscientiousness and agreeableness to rise and average neuroticism to fall across adulthood.
    • Ex: The average 40-year-old meets deadlines more often than the average 20-year-old.
    • Ex: A group measured at its twentieth college reunion will probably have a lower average neuroticism score than it has today.
  • The maturity principle describes an average pattern. It does not describe every person.

A Group Trend Is Not a Rule for a Person

  • Every study reports a group average.
  • Inside each group:
    • Some people changed more than the average.
    • Some people changed less.
    • Some people changed in the opposite direction.
  • The maturity principle tells us how the average moved. It does not tell us what happened to one person.

Why Do Average Scores Change?

  • The Situation: Social roles can reward certain ways of acting at different points in our lives:
    • Ex: Jobs and parenting often reward being more reliable (conscientiousness) and patient (agreeableness).
    • Ex: Being financially independent can provide opportunities for new experiences (openness).
  • The Person: Personality can also affect which roles a person enters to begin with.
    • Ex: People high in extraversion more often choose jobs that involve talking to strangers all day.
    • Ex: People high in openness more often move to new cities or study abroad.
  • Correlation, not Causation!

Can People Change on Purpose?

  • Yes, by degrees, although it requires continued effort to make changes last.
    • Openness: Visit new places; join a club or organization; purposively take a different perspective in a discussion.
    • Conscientiousness: Make a daily schedule; break assignments into steps; complete tasks before their deadlines.
    • Extraversion: Start a conversation; speak during a group discussion; invite someone to do something.
    • Agreeableness: Listen without interrupting; keep a gratitude journal; intentionally look for compromises during disagreements.
    • Emotional Stability: Practice slow breathing; question overly negative thoughts; attend therapy.

Practice

For each example, decide whether the people kept their positions and whether the group’s average moved.

  1. Ten years after a high school class was first surveyed, the same students rank in nearly the same order on openness, but they all scored higher than they did in high school.
  2. Over ten years, a church choir’s average extraversion has been the same. But the quiet members have become the talkative ones, and the talkative ones have gone quiet.
  3. “Everyone in our unit got more careful after the accident,” the foreman says. “The careless ones are still the careless ones.”
  4. The maturity principle states that the average neuroticism score fell between ages 20 and 40. Dylan’s score rose.
  5. Twenty years after graduation, five roommates have the same average agreeableness they had in college and remain in the same order.
  6. The firm’s new hires are more agreeable on average than the people they replaced.

Practice: Answers

  1. Positions held and the average moved: rank-order stability and mean-level change.
  2. Positions changed and the average held: low rank-order stability and no mean-level change.
  3. Positions held and the average moved: rank-order stability and mean-level change.
  4. The group’s average moved down, but Dylan’s score moved up. We do not know whether Dylan kept his position compared with the other people.
  5. Positions held and the average held: rank-order stability and no mean-level change.
  6. Neither applies. Two different groups were measured once. Stability and change require measuring the same people more than once.

Applying the Core Themes

  • Stability AND Change: People can keep their positions compared with others while the group’s average changes. Both can happen at the same time.
  • Degrees, NOT Types: Personality change is movement along a spectrum, not a switch from one personality type to another.
  • Person AND Situation: Adult roles may help change average scores, but the same role can affect different people in different ways.
  • Limited Self-Knowledge: People judge their own change by comparing their present self with a remembered past self. Measuring them at both times gives us better evidence.

Next Time

  • Personality becomes more stable with age, but it never becomes fully fixed.
  • People also differ in how much they change.
  • What produces the stability, and what produces the change?
    • Next: genes, environments, and twin studies.