Rita's behavior encompasses many kinds of risk. In the long term, the most dangerous of her activities are smoking and drinking. There are nearly 80 times as many deaths per year from tobacco and alcohol as from cocaine and heroin. But Rita thinks only of today's gratifications, not their associated dangers.
Rita is a fictional character, but she represents a kind of general risk-taker, one whose behavior encompasses many different activities. Such broad-spectrum risk-takers not only exist, I have discovered, but have a distinctive personality makeup that is the product of both genes and experience. It is important to identify such people because they create significant public health problems, for others as well as themselves. But for all the danger they put themselves in, they personify—perhaps magnify is more precise—a human trait that is very much responsible for our survival as a species.
Over the decades I have studied a personality trait called sensation-seeking—the pursuit of novel, intense and complex sensations and experiences, and the willingness to take risks for the sake of such experience.
Risk-taking is not the main point of sensation-seeking behavior; it is merely the price such people pay for certain kinds of activities that satisfy their need for novelty, change and excitement. In fact, many of the things that high sensation-seekers do are not at all risky. They enjoy high-intensity rock music, view sex and horror films, travel to exotic places, and party without drugs.
Sensation-seeking can also extend to the physical, involving unusual or extreme sports such as skydiving, hang gliding, scuba diving, auto racing, rock climbing and whitewater kayaking. An interest in participating in such sports describes one subcategory of sensation-seeking: thrill- and adventure-seeking.
There are other kinds of sensation-seeking that are expressed not through physical action but through the casting off of inhibitions in a social setting (disinhibition), through deviant lifestyles (experience-seeking), and through the pursuit of change for change's sake (boredom susceptibility). This variety of sensation-seeking has been related to such risky activities as smoking, drinking, drugs, unsafe sex, reckless driving and gambling.
Some psychologists have suggested that risk-taking is linked to neuroticism, a personality trait. They see it as an expression of neurotic conflict, a form of acting out or counter-phobic behavior. Our previous research on physical risk-taking refutes such an explanation; it suggests that risk-takers do not expressly exhibit traits of neuroticism or anxiety.
It has also been suggested that high-risk behaviors like reckless driving, an antisocial activity if ever there was one, are a vehicle for expressing aggressiveness and hostility. Or perhaps risk-taking might be just an expression of a generalized need for activity itself, as is the case with hyperactive individuals, who provide their own stimulation through activity to overcome boredom.
Yet many risky activities, such as drinking and drug use, are done in a social setting. So it is possible that these activities, particularly in a college population, may be related to sociability. In a study, my colleagues and I looked at college students, many of whom were currently engaging in some or all six kinds of risky activities: smoking, drinking, drugs, sexual behavior, reckless driving and gambling. We attempted to answer two questions: Is there indeed such a thing as a generalized risk-taking tendency, as our earlier studies had suggested, and if so, what type of personality traits are associated with this tendency?
Our prediction was that many or all of the kinds of risky activities would be related to impulsive sensation-seeking. But we also looked at the role of neuroticism-anxiety, aggression-hostility, sociability and activity.
We measured these traits using the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ), a five-factor personality test that I developed with my colleagues.
We also assessed smoking, drinking, drug use, sex, driving and gambling on separate risk-taking scales related to each particular kind of risky behavior. The driving-risk scale asked about typical driving speeds, response to traffic signals and following distances at high speeds, among other factors. To assess risky sexual behavior, we asked about the number of sexual partners and whether or not a condom is used, and if so, how consistently.
The first question we sought to answer was whether the six arenas of risk are interrelated, pointing to a concept of generalized risk-taking.
As it turned out, smoking, drinking, sex and drugs work in tandem with each other. Among both males and females, students who did one tended to do the others. (We know from other studies that they also listen to rock and roll.)
Reckless driving, however, was related to only one other arena of risk: drinking. Unfortunately, this connection is often deadly.
Among males, gambling was related to drinking and sex. But among women, it was not related to any other kinds of risk-taking.
With the single exception of gambling among women, we felt justified in computing a generalized risk-taking score based on all six kinds of risk-taking. On the basis of their total risk-taking score, we divided the participants into high, medium and low risk-takers and compared these three groups on the five personality scales in the ZKPQ.
The results were similar for both men and women. The high risk-takers scored high on three of the five personality traits: impulsive sensation-seeking, aggression-hostility and sociability, proving them the most salient predictors of risk-taking personality.
Among the groups representing three levels of risk-taking, there were no significant differences on neuroticism-anxiety or activity, suggesting these traits play an insignificant role in risk-taking behavior.
There were, however, notable links between other personality traits and specific kinds of risky behavior. Heavy drinking was associated with all three of the personality traits related to general risk-taking tendency: impulsive sensation-seeking, aggression-hostility and sociability.
But smoking and drug use beyond marijuana were related only to impulsive sensation-seeking and aggression. That finding is interesting because in a previous study we found that the same two traits were also higher among prostitutes than among a control group. The combination of impulsive sensation-seeking and aggression was also related to antisocial personality disorder among male prisoners and to level of cocaine abuse.
Previous research has shown that the use of illegal drugs, even of marijuana, relates to a higher degree of sensation-seeking than is found among those who use only alcohol. The step from legal drugs (tobacco and alcohol) to illegal ones is one taken only by the higher sensation-seekers. The illegal drugs provide more novel and intense sensations and experience at the cost of greater legal and social risks.
In our study, as well as in others, men proved higher risk-takers than women. They also scored higher on impulsive sensation-seeking than women. When we analyzed the gender difference in risk-taking we found that it was entirely a function of the difference between men and women on impulsive sensation-seeking. This is only one of several pieces of evidence suggesting that impulsive sensation-seeking is a basic personality dimension.
Humans are a risk-taking species. Our ancestor Homo sapiens originated in East Africa, and within the relatively short span of 100,000 years or less spread over the entire globe. It turns out that explorativeness may be the key to the survival of the species.
The hunting of large and dangerous game by men required a type of thrill- and adventure-seeking that also contributes to the success of the human race. Over the millennia, men also found in combat and war an outlet for their need for adventure.
Mating, too, was a dangerous game that required risk-taking. The innate incest taboo drove men to seek mates outside their small groups, sometimes from unfriendly groups.
The fact that a trait like sensation-seeking characterizes our species does not mean that individuals don't differ in the degree to which they have that trait. Genetic assortment may maintain variation in a trait like sensation-seeking, which is most adaptive when it is in the middle range: Too much risk-taking leads to an early death, too little to stagnation.
Studies of the heritability of sensation-seeking in humans have used classical twin-comparison methods. Comparisons of identical and fraternal twins in which both siblings were raised in the same families show that sensation-seeking is about 60% genetic. That is a high degree of heritability for a personality trait; most range from 30% to 50%.
A study of identical and fraternal twins separated at birth and adopted into different families showed the same heritability. It also indicated that the environmental contribution to sensation-seeking (accounting for 40% of the trait, or less) is due not to the shared family environment but to the environment outside of the home, such as friends and accidental life experiences.
If children resemble parents or siblings in sensation-seeking, it is probably due to shared genes rather than the influence of the family. Friends and others outside of the home may provide behavioral models and reinforce the disposition carried in the genes.
Genes play yet another role in risk-taking: They influence two other personality traits associated with general risk-taking, including the traits of aggression, or its obverse, agreeableness, and for sociability, the main component of extroversion.
Molecular genetics has made it possible to identify major genes influencing personality and forms of psychopathology. A group of scientists in Israel were the first to find an association between novelty-seeking (a trait very highly correlated with impulsive sensation-seeking) and a gene that codes for a class of dopamine receptor, the dopamine receptor-4 (DRD4) gene.
Dopamine is an important brain neurotransmitter, active in pathways related to the brain's intrinsic reward and pleasure centers. It responds to stress, and enables people not only to see rewards but to take action to move toward them.
Two major forms of the dopamine receptor-4 gene exist, a long and a short version of the same base DNA sequences. The long form is found in a preponderance of those individuals who are high in novelty-(sensation-) seeking. The same form of the gene is found in a high proportion of opiate drug abusers, a high sensation-seeking group.
The particular gene accounts for only about 10% of the genetic variance. But now that the human genome has been defined, many of the other genes contributing to this and other personality traits may soon be discovered.
Genes, however, do not directly make traits. They make proteins that shape our nervous systems. Between a gene and a behavior stand, among other things, the structure and function of the brain and the biochemistry of neurotransmitter systems.
The greatest risk-takers are young males in their adolescent years—a fact reflected in their high rates of auto accidents, binge drinking, drug use and pathological gambling. The military has always preferred younger men for soldiers, not only because of their physical strength but for their willingness to risk their lives in combat.
Young men of this age are also at their peak on sensation-seeking. And, not surprisingly, they are at their peak in levels of the sex hormone testosterone. Testosterone correlates particularly with the disinhibitory types of sensation-seeking—those associated with drinking, drugs, sex and antisocial behavior. It is also associated with normal traits like dominance, sociability and activity. As testosterone levels drop, men's aggressive, antisocial tendencies begin to mellow. Sensation-seeking scores of men aged 50 to 59 are half those of males aged 16 to 19.
Women also have testosterone, but less of it. Still, the hormone is linked to behaviors in women similar to those in men, such as assertiveness, aggression and sexual arousal.
Another biological correlate of sensation-seeking is the enzyme monoamine oxidase (MAO), active in the brain. Monoamine oxidase functions as a regulator, keeping neurotransmitters in balance. It could also contribute to the gender and age differences in sensation-seeking and risk-taking.
A form of monoamine oxidase called type B is particularly related to sensation-seeking—and to regulation of dopamine. The link between MAO and dopamine is notable in light of the fact that the dopamine-4 receptor gene has been connected to sensation-seeking, and another dopamine receptor, D2, has been connected with substance abuse, a particular form of risk-taking behavior.
The enzyme monoamine oxidase is low in high-sensation-seekers, implying a lack of regulation. What is more, levels of MAO are known to be higher in women than in men, and MAO levels in brain and in the blood rise with age. Further evidence that MAO is involved in sensation-seeking is that low MAO levels are also found in forms of psychopathology characterized by impulsive tendencies to seek immediate rewards without regard for consequences.
Sensation-seekers who are drug users have found a direct pathway to activate the brain's pleasure centers. Others seek the same arousal through exciting stimuli and experiences. Risk is not a necessary requirement for sensation-seeking, although it does intensify the thrill for a high sensation-seeker.
Although risk-taking has negative aspects and can even prove fatal, it is a positive force as well. Without risky experiences, humanity would stagnate; there would be little impetus for discovery. Risk-taking was obviously adaptive in earlier hominids. The trait persists—but there is little left to explore. What is more, work is anything but exciting for many people.
Modern life, with its protected cultures and curtailment of war, has not wiped out the need for excitement. Some people find it through other people, in relationships and sex. Others need more of a thrill, and go hang-gliding or bungee-jumping, although the most common everyday outlet for sensation-seeking is reckless driving. My work has shown that people have basic need for excitement—and one way or another, they will fulfill it.