People tend to maintain their distinctive patterns of behavior throughout life. A child who is more extraverted than most other children is likely, when she gets older, to be more extraverted than most other adolescents, more extraverted than most other adults, and finally, when the time comes, more extraverted than most fellow residents of the Golden Acres Retirement Home. Likewise, a child who is either more or less neurotic, agreeable, conscientious, or open than his peers is likely to maintain this distinction throughout life, too (Costa & McCrae, 1994). Psychologists call this kind of stability rank-order consistency. Like the consistency of personality in general (see Chapter 4), it does not mean people do not change over the years. It just means they tend to maintain the ways in which they are different from other people the same age.
Evidence for Stability
The evidence for this kind of stability is widespread and impressive. In one study, personality trait scores from the same people measured 10 years apart correlated between r= .60 and r= .90, which are high numbers by any standard (Hopwood et al., 2013). In another study, elementary school children described by their teachers as especially “adaptable” were seen (in a videotaped interview) to act in a relatively cheerful and intellectually curious manner when they were middle-aged adults, and children rated as “impulsive” were seen, decades later, to talk more and in a louder voice than most other adults the same age (Nave, Sherman, & Funder, 2010). Even people who experience natural disasters such as earthquakes often turn out to be resilient; despite everything, most manage to maintain their core personality traits (Milojev, Osborne, & Sibley, 2014).
It is also possible to predict adult life outcomes on the basis of personality ratings in childhood. For example, 4- to 6-year-old children rated as more “inhibited” than most of their peers were slower to find a stable romantic partner and slower to find a first job 19 years later, compared to children rated as less inhibited (Asendorpf, Denissen, & van Aken, 2008). In general, children with extreme scores on trait ratings, or those who were rated as especially “difficult,” tend to have problems after they grow up (Van den Akker et al., 2013).
Personality disorders are generally stable across the life span—though not as stable as basic personality traits—and being in therapy doesn’t seem to make much difference (Ferguson, 2010; Hopwood, et al., 2013; see also Chapter 17). On a more positive note, 8- to 12 year-old children who received high ratings on traits such as “mastery motivation” (the desire to learn from failure) and agreeableness were found, 20 years later, to have greater achievement in school and at work, less antisocial conduct, and better relationships with their romantic partners and friends (Shiner, Masten, & Roberts, 2003).
Causes of Stability
What keeps personality so stable over such long periods of time? There are several causes.
FROM TEMPERAMENT TO PERSONALITY First, and perhaps most obviously, many aspects of the individual that affect his or her personality remain constant for years. Some of these pertain to the individual’s physical body, including his or her DNA.2 The personality that one begins with—which is traditionally called temperament in young children—is to some degree determined by the genes inherited from one’s parents. Fundamental behavioral and emotional tendencies stem from that very early root, and persist throughout life. However, the effects of these fundamental tendencies change with age, a process called heterotypic continuity (Caspi & Roberts, 1999). For example, a shy child at a social gathering might hide behind a parent; a shy adult is unlikely to do that, but still might avoid conversing with strangers. An aggressive child might express disagreement by kicking a playmate; an aggressive adult is more likely to get into a verbal argument than a physical one (though adults get into physical fights too).
According to one analysis, the three basic aspects of childhood temperament are positive emotionality, negative emotionality, and “effortful control” (Vroman, Lo, & Durbin, 2014). Positive emotionality may be the precursor (via heterotypic continuity) of the adult trait of extraversion, negative emotionality the precursor of neuroticism, and effortful control the precursor of conscientiousness and agreeableness (Ahadi & Rothbart, 1994). Much more will be said about the biological and genetic foundations of personality in Chapters 8 and 9.
PHYSICAL AND ENVIRONMENTAL FACTORS Beyond one’s genes and internal biology, visible attributes of the body are no doubt important as well. Whether you are physically female or male, tall or short, or meet your culture’s conventional definition of attractiveness—these are facts that you can do little or nothing about; they will affect the kind of experiences you have and therefore the kind of person you become, and they will remain the same throughout much or all of your life. Other consistent influences reside in the world that surrounds you. You might be rich or poor, or you might live in a city or in the country, or you might come from a large family or small one. These facts, too, are largely, if not entirely, out of your control, and will continuously affect how you think, feel, and behave—the three elements of the personality triad introduced in Chapter 1.
BIRTH ORDER One long-lasting fact about you, over which you had no influence whatsoever, is your birth order. But does it really matter whether you were the firstborn in your family, or came along later? Psychologists have argued about this question for years (Rodgers, Cleveland, van den Oord, & Rowe, 2000). Much of the debate centers around a proposal by the psychologist Frank Sulloway, who says that parents tend to lavish the most attention and resources on their firstborn child, who then becomes likely to identify with the parents’ values and goals, and may even take on the role of “assistant parent” in raising the siblings who come along later (Sulloway, 2001). The later born child, however, has to find a niche in the family not already occupied by the child (or children) who came before, has fewer responsibilities within the family, and so is more likely to draw on other sources for relationships and values. As a result, firstborns grow up to favor “the establishment,” are conventionally ambitious, and support traditional values. Laterborns are more likely to be independent, open-minded, and even rebellious.
While this proposal sounds reasonable, research to establish whether it is actually true has turned out to be difficult. For one thing, it is not enough to simply compare firstborns with laterborns if they come from different families, because families are often dissimilar to each other in many ways that might be important. Unless the researcher is careful, effects that appear to be due to birth order could stem from factors such as family size, family income, or parental genetics. But at least one study that attempted to carefully account for these variables did find that firstborn children were more conscientious than second born children (in families that had at least two), and that the second born children were higher on openness to experience. Both of these findings are consistent with Sulloway’s proposal (Healey & Ellis, 2007). A review of the literature written by Sulloway himself concluded that in addition to firstborns scoring higher on conscientiousness, later born children tended to score higher on extraversion, openness to experience, and agreeableness—but neuroticism showed no difference at all (Sulloway, 2010). However, none of the effects were very large—the overall correlation between birth order and conscientiousness, which was the largest one among the Big Five traits, was r= –.18.3
Another study found no relationship at all between birth order and rebelliousness, contrary to the prediction that laterborns would score higher than firstborns on this trait (Cundiff, 2013). And, perhaps finally, a recent and very large study of several thousand people in about a thousand different families directly contradicted Sulloway’s hypothesis, finding no differences whatsoever in the personalities of earlier and later-born individuals (Rohrer, Egloff, & Schmukle, 2017).4 I said “perhaps finally” just now because I actually don’t think the idea of birth order being important will go away so easily; people just seem to intuitively believe, or want to believe, that it matters. So I expect the debate to continue. If you have sisters or brothers, you might do a small informal study of the effect of birth order within your own family. In what ways are you different from your older or younger siblings, and why?
EARLY EXPERIENCE Early adverse experiences can have consequences that persist for many years, especially for children who are already sensitive and vulnerable (Slagt, Dubas, Deković, & van Aken, 2016). Adults who remember being rejected by either of their parents, as children, have difficulties in forming relationships throughout their lives (Khaleque & Rohner, 2012). Similarly, the experience of being bullied in childhood (at age 11) can lead to symptoms such as anxiety, paranoid thoughts, and disorganized thinking in late adolescence (at age 16). Children who were already somewhat depressed, anxious, or impulsive have especially bad reactions to experiences such as being kicked, called names, or rejected by their peer group (Singham et al., 2017). Other kinds of stress during childhood, such as growing up in poverty or being maltreated, can produce a lifelong pattern of chronic (biological) inflammation, which can lead to frailty, fatigue, and general ill health (Fagundes & Way, 2014). These outcomes, in turn, create a long-term tendency to have stronger emotional reactions to ordinary, daily stress (Glaser, van Os, Portegijs, & Myin-Germeys, 2006). The effects of early bad experiences can be difficult to undo. Romanian orphans who spent more than 6 months in an orphanage, and then were adopted into prosperous British families when they were 6 years old, nonetheless suffered increased risk of later difficulties relating to their social group, low educational achievement, and unemployment (Sonuga-Barke et al., 2017).
Fortunately, some parents are successful at creating environments for their children that promote good outcomes. Highly educated parents appear to be especially likely to succeed at this. A large study of seven samples that examined a total of more than 60,000 people from the ages of 7 to 95 found that parents with more years of education had children who turned out, as adults, to be more open, extraverted and emotionally stable—but not more conscientious! This finding held for both biological and adopted children, which indicated that it really was the environment that mattered, not just the genetics of the parent (Sutin, Luchetti, Stephan, Robins, & Terracciano, 2017). What the study did not reveal is exactly what the better-educated parents did that produced these favorable outcomes for their children. What do you think it might have been?
A hint might come from another study, which looked at relationships between the childhood family environment and adult self-esteem in 8,711 American participants who were followed from ages 8 to 27. The environments of the children who grew up to feel good about themselves were characterized by cognitively stimulating activities such as being read to, physical comfort, the presence of the father, and all-around prosperity (Orth, 2018). Is this kind of environment more likely when the parents are better educated?5
PERSON-ENVIRONMENT TRANSACTIONS One reason personality remains stable over the years is that people respond to, seek out, and even create environments that are compatible with, and may magnify, their personality traits. These processes are called person-environment transactions.6 There are several types (Caspi, Elder, & Bem, 1987; Roberts, Wood, & Caspi, 2008; see Table 7.1). As an example of an active person-environment transaction, an aggressive person may be attracted to (and be attractive to) similarly aggressive friends, which may put that person into environments where conflict, fights, and even delinquency are common. A more scholarly person, by contrast, may prefer to hang out with fellow denizens of the library, and in that environment develop a strong academic record and perhaps a successful professional life. Of course, such environments are not always completely freely chosen. Someone who gets arrested did not exactly choose the jail environment, but the experience may affect her personality. And even the most studious scholar may find that he failed to be admitted to the college of his choice. So happenstance—luck—plays a role here, too.
Table 7.1PERSON-ENVIRONMENT TRANSACTIONS THAT CAN MAGNIFY PERSONALITY TRAITS OVER TIME
Transaction
Process
Examples
Active person– environment transaction
Person seeks out compatible environments and avoids incompatible ones
Aggressive person goes to bar where fights are frequent; introvert avoids social gatherings
Reactive person– environment transaction
Different people respond differently to the same situation
Extravert finds party enjoyable; introvert finds same party unbearable
Evocative person– environment transaction
Aspect of an individual’s personality leads to behavior that changes the situations he or she experiences
Conscientious person tells group “it’s time to get to work”; disagreeable person starts argument over minor matter
The reason people tend to seek out environments compatible with their traits is that they may find other kinds of environments unpleasant. A true extravert might feel miserable sitting quietly on the porch, while a true introvert suffers just as much at a noisy party (Lucas & Diener, 2001). This kind of pattern of differential response to situations is called a reactive person-environment transaction.
People do not just choose their environments; they change them.
People do not just choose and experience their environments; they change them. This process is called an evocative person-environment transaction. For example, parents who are emotionally positive and uninhibited tend to be highly responsive to their 3- to 6-year-old children. At the same time, children of this age who are emotionally positive and self-controlled evoke better responses from their parents (Wilson & Durbin, 2012). The path of influence from parent to child is a two-way street; depending on their personalities, each draws out behaviors from the other in a way likely to magnify the effect on the child’s development over time.
Similar transactions occur at every age. The atmosphere of a study group or a work team can change in a moment if just one person says, “Let’s stop working so hard and go get some beers,” or says, “Let’s quit fooling around and get something done for a change.” The person who does either of these things affects the environment of the people around him, but also—and probably consistently—affects his or her own environment, too. Over time, the second person will inhabit environments that promote achievement; the first person, not so much. Long-term consequences of persistent patterns like this can be significant. People described as “ill-tempered” (low in agreeableness) chronically create situations where people are arguing or fighting with each other and, as a result, are more likely to suffer outcomes such as divorce and unemployment (Ozer & Benet-Martínez, 2006).
Individual differences in personality become more consistent as one gets older.
CUMULATIVE CONTINUITY AND MATURITY According to one major summary of the literature, the correlation coefficient reflecting consistency of individual differences in personality is .31 across childhood, .54 during the college years, and .74 between the ages of 50 and 70 (Roberts & DelVecchio, 2000).7 While all three figures indicate impressive stability, it does appear that individual differences in personality become more consistent as one gets older. This conclusion has been called the cumulative continuity principle. This principle asserts not only that personality traits are relatively stable across the life span, but also that consistency increases as a person matures (Roberts, Wood, & Caspi, 2008; see also Anusic & Schimmack, 2016, for a replication of this finding). One result is that people’s self-views of their own personality come to agree better with ratings by others as they mature between the ages of 14 and 29 (Rohrer et al., 2017). It’s easier to agree about what somebody is like when that person behaves consistently, and young adults are more consistent than adolescents are.
When traits do change, they tend to change together—one trait changes, and others do, too (Klimstra, Bleidorn, Asendorpf, van Aken, & Denissen, 2013). The flip side of this finding is that when one trait stays the same, so do the others—and this observation is especially true in older adults (specifically, older than 70). The main reason personality becomes more stable during the transition from child to adult to senior citizen seems to be that one’s environment also gets more stable with age (Briley & Tucker-Drob, 2014). Among other factors, older people are more likely to have finally decided where they live, who they live with, and what they do for a living. As the saying goes, they’ve “settled down.”
An intriguing and surprisingly hopeful recent finding is that people may be becoming more psychologically mature around the world!
But it’s not just a matter of age—stability stems from psychological maturity. From a psychological point of view, “maturity” generally refers to behavioral consistency and also to the specific traits that help a person to fulfill socially important adult roles such as being a spouse, a parent, or a worker. These traits include self-control, interpersonal sensitivity, and emotional stability. Adolescents with relatively mature personalities—in these terms—change less over the next 10 years than do others, the same age, who are less mature (Donnellan et al., 2007). An intriguing and surprisingly hopeful recent finding is that people may be becoming more psychologically mature around the world! You might have heard of the “Flynn effect,” which is the apparently robust finding that IQ is increasing slowly but consistently, everywhere (Pietschnig & Voracek, 2015). A recent study proposed that something similar may be happening in the domain of personality, with people around the world increasing gradually but consistently in traits such as self-confidence, sociability, leadership motivation, and achievement striving, among others (Jokela et al., 2017). There do not seem to be many indications that the world is becoming a better place, but maybe this is one.
THE END OF HISTORY? At what point does personality stop developing? Take a moment and ask yourself a couple of questions. Has your personality changed over the past few years? The answer might depend to some degree on how old you are. Most people about to graduate from college think they changed a lot over the previous 4 or 5 years, and they are usually right (Robins, Noftle, Trzesniewski, & Roberts, 2005). Fewer middle-aged people think they have changed significantly over the previous 6 years—in one study, about 38 percent of the respondents thought they had changed “a little”8 (Herbst, McCrae, Costa, Feaganes, & Siegler, 2000). But now ask yourself another question: Will my personality be different 10 years from now? According to some research, most people think the answer to this question is No (Quoidbach, Gilbert, & Wilson, 2013). From the perspective of the present moment, today looks like “the end of history” and we feel like finished products. We expect to change less in the future than we have in the past, or even not at all. But if we really do think this, it’s an illusion. The evidence indicates that personality continues to develop throughout the life span. You won’t always be exactly the way you are now—probably.
The term often used for the “personality” of very young, pre-verbal children. Aspects of temperament include basic attributes such as activity level, emotional reactivity, and cheerfulness.
The reflection of the consistency of fundamental differences in personality that changes with age; e.g., the emotionally fragile child will act differently than the emotionally fragile adult, but the underlying trait is the same.
The idea that personality becomes more stable and unchanging as a person gets older.
Notes
2. Although, the stability of the effects of DNA is not so simple. Recent work on epigenetics has shown that experience can affect how, when, or even whether a gene is expressed. More will be said about epigenetics in Chapter 9.
3. The negative sign on the correlation reflects that people with lower (earlier) birth order had higher conscientiousness scores.
4. The single exception was one item where people rated the degree to which they were “eager for knowledge”; first-borns rated themselves slightly higher, on average.
5. Yes, I think so. Stay in school. Your children will thank you someday.
6. The term “transaction,” in this context, means that one psychological factor is affecting the other, and vice versa. The person chooses or changes his or her environment even while the environment is changing the person.
7. Within each age range, personality was compared at two times about seven years apart.
8. Nine percent thought they had changed “a good deal,” and 53 percent thought they had “stayed the same.”