The controversy continues today as to whether personality remains stable across the life span or whether it changes. Given that personality traits have been shown to be important predictors of mental and physical health as well as psychological well-being, potential changes in personality can have important implications for gains and declines in such life outcomes. However, as this chapter indicates, there is no clear evidence for one position or the other. An important aspect to consider in this controversy is the level of analysis in which stability and change is determined. Typically, stability and change are examined through mean level comparisons over time. In other words, does an age group’s mean level on a particular personality trait such as extraversion remain stable from one point in time to another (say 10 years apart) or does it change?

Mroczek and Spiro (2003) suggest that examining change in mean levels of a personality trait does not adequately address stability and change at the level of the individual.

In other words, a group mean hides the extent to which individual people change. In their recent work, they examine the extent to which each person in their longitudinal study changes or remains the same over time. This allowed them to ask the questions "Do some people remain stable whereas others change?" and, if there are people who change, "Do some people change more than others?" They examined individual patterns of change for 1,366 men over a 6-year period. They ascertained personality change and stability by examining each individual’s change pattern, called an individual growth curve. They then grouped each individual into categories of no change in the personality trait, increases in the personality trait, and decreases in the personality trait. Preliminary findings indicate that over a 6-year period, a large proportion of older men remained stable with respect to extraversion, whereas a smaller but substantial proportion of men changed. In addition, among those who changed, an equal number of men increased and decreased in extraversion. The researchers found similar results for neuroticism. These findings indicate important individual differences in the extent to which men change.

This approach allows a more detailed answer to questions of stability and change. When we rely on the major longitudinal approaches such as McCrae and Costa’s (1994), we see that at the group level there is primarily stability. However, when we examine individuals’ growth curves, we see a more complete picture of personality development. Whereas a large proportion of individuals may remain stable, there is a substantial group of individuals whose personality traits either increase or decrease over time. Perhaps we can see a resolution to this debate in the future as more intraindividual studies on personality development emerge.

that may be linked to increased stability, such as a stable environment or identity integration, account for age and trait stability (Roberts & Del Vecchio, 2000; Roberts et al., 2002).

Another important issue for future research is the role of life experiences. If a person experiences few events that induce him or her to change, then change is unlikely. In this view a person will be at 60 very much the same as he or she is at 30, all other factors being held constant. As we will see later, this idea has been incorporated formally into other theories of personality. On the basis of dispositional traits, then, we should have little difficulty knowing our high school classmates many years later.

Personality 325

Concept Checks

1. What are the five dimensions of the five-factor model?

2. What criticisms are aimed at the five-factor model?

3. What were the main findings from more current research on changes in dispositional traits?

4. Are dispositional traits stable over time?