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Conscientious Adults: Then and Now

If our unexpected discovery about childhood conscientiousness and its relevance to long life is not a fluke, then we should also be able to find confirming evidence by studying conscientious adults.

Almost two decades after starting, in the summer of 1940, Dr. Terman approached Patricia and the other members of his select study again. He gave them an extensive new series of tests and measures with such questions as “Are you thrifty and careful about making loans?” and “How persistent are you in the accomplishment of your ends?” From these results we worked for months to construct and validate a new series of personality scales. At times, we also incorporated similar questions that Terman asked the participants in 1950.

Studies of health across the life span face an intriguing dilemma. In order to see whether personality in childhood and young adulthood predicts long life, a result that can’t be seen until decades later, we necessarily need to use “old” data. In our case, information from the early and mid-twentieth century is being used to predict longevity into the twenty-first century. But years later, new, improved measures are in vogue, and the dusty old measures and techniques are likely subject to criticism. As Dale Carnegie put it, “Any fool can criticize, condemn and complain, and most fools do.”

Short of time travel, how can we be sure that the measures we have from the 1920s, 1940s, and 1950s reflect what we understand about personality today? What at first seemed simple gradually became more and more complex. We decided to administer the Terman questionnaire items to a contemporary sample of people. More than a half century after Dr. Terman measured the personality of Patricia at thirty years old, we recruited a new group of young adults in California and asked them the exact same questions. We also recruited a sample of parents to rate their young children on Terman’s scales, just as parents of the Terman participants had done in the 1920s.

We then gave these new participants some modern, well-validated personality tests. Through a series of statistical analyses, we were able to check the old data against new data, thereby creating valid, modern personality measures for Patricia and her associates. It was almost as if we had gone back decades and measured Jess Oppenheimer’s personality by finding a modern-day doppelganger. We did this in the technical, statistical way, and then, just to be sure, we examined all the scale items in a rational, commonsense manner. Fortunately, all of the data analyses fit together quite well.7 Dr. Terman’s approach to personality holds up nicely and can help us predict our own futures.

Doing the right statistical analyses in such attempts to predict long life is much more difficult than might be imagined. Long-term longitudinal studies are especially challenging because participants come and go, rejoin or drop out, disappear or are discovered, and live or die. In addressing these and related statistical issues, we were fortunate to have Professor Joseph Schwartz as a key research collaborator. Joe has one of best analytic minds in this field.

Revenge of the Virtuous

Conscientiousness, which was the best predictor of longevity when measured in childhood, also turned out to be the best personality predictor of long life when measured in adulthood. The young adults who were thrifty, persistent, detail oriented, and responsible lived the longest. Patricia was one of these, having told Dr. Terman that she enjoyed “planning [her] work in detail” and tended to “drive [herself] steadily.” When asked about how she typically pursued goals, she indicated that she was persistent and that she had “definite purposes.” Patricia also reported being “thrifty and careful about making loans” and not at all impulsive. In fact, she had done very well in college and was expecting to have a highly successful career.

By the end of the twentieth century, 70 percent of the Terman men and 51 percent of the Terman women had died. It was the unconscientious among them who had been dying in especially large numbers. This confirmation in adulthood was particularly impressive because personality was being measured differently. Conscientiousness in childhood was measured by parent and teacher ratings. Conscientiousness in adulthood was measured by self-report questionnaires—our analyses of how participants described themselves and their activities. In both cases—childhood and adulthood—conscientiousness was the key personality predictor of long life.

Why Do the Conscientious Stay Healthier and Live Longer?

We thought of three possible reasons for why conscientious individuals tend to stay healthier and live longer. To our great surprise, all three are true. The first reason, perhaps most obvious, is that conscientious people do more things to protect their health and engage in fewer activities that are risky. They are less likely to smoke, drink to excess, abuse drugs, or drive too fast. They are more likely to wear seat belts and follow doctors’ orders. They are not necessarily risk averse but they tend to be sensible in evaluating how far to push the envelope.

The second, and least obvious, reason for the health benefits of conscientiousness is that some people are biologically predisposed to be both more conscientious and healthier. Not only do they tend to avoid violent deaths and illnesses linked to smoking and drinking, but conscientious individuals are less prone to a whole host of diseases, not just those caused by dangerous habits. We and others are uncovering this startling finding again and again—conscientious folks are less likely to die from all sorts of causes. While we are not yet sure of the precise physiological reasons, it appears likely that conscientious and unconscientious people have different levels of certain chemicals in their brains, including serotonin. Serotonin is the neurotransmitter targeted by antidepressant drugs like Prozac, Paxil, and Zoloft. Individuals with low levels of serotonin tend to be much more impulsive. Importantly, serotonin is also necessary to regulate many health-relevant processes throughout the body, including how much you eat and how well you sleep.

This is no cause for fatalism, however. Neurotransmitter levels can change over time, and being biologically predisposed toward certain physiological processes is not a death sentence any more than being predisposed to depression means you will absolutely fail to thrive and find satisfaction in life. As we will see, some Terman subjects who started out low on conscientiousness (i.e., who were impetuous and impulsive children) led long and healthy lives.

We’ve saved the best for last. The most intriguing reason conscientious people live longer is that having a conscientious personality leads you into healthier situations and relationships. In other words, it is not only that conscientious people have better health habits and healthier brains, but also that they find their way to happier marriages, better friendships, and healthier work situations. That’s right, conscientious people create healthy, long-life pathways for themselves.

In and Out of Conscientiousness

Some people do change, and they travel down a path that leads them far away from the habits of their youth—for good or for ill. While we found a consistent link between dependable kids and their future adult selves, we also confirmed that human beings can be inconsistent creatures. Some wild frat boys quit drinking the morning after their fortieth birthday. Cautious others abandon their sensible lifestyle in midlife and buy a red sports convertible. How is a change in long-term conscientiousness relevant to health?

We decided (with the advice of Dr. Joe Schwartz) to compare four kinds of people:

• The first is someone like Patricia who was highly conscientious (in the top quartile) in both childhood and adulthood.
• The second is an individual who was conscientious in childhood but turned unconscientious by adulthood.
• The third is someone, such as the tactful and charismatic James, who was decidedly low on this trait as a kid but became one of the most conscientious subjects by the time he reached young adulthood.
• The fourth kind was unconscientious in childhood and remained so in adulthood.