 Well, the nature of science today is that it really is no longer possible for any one person to do it all. Modern science is now a cooperative venture, best conducted by teams of specialists, each contributing part of the solution to very complex puzzles. Unravelling the genetic and environmental interaction underlying human developmental psychology is no exception to this. Abshalam's Caspi is a great exemplar of a team scientist. He's involved in several multi-discipline long-term projects in three different countries studying complex puzzles of personality development. Dr. Caspi recognises the value of different methods and has incorporated molecular and epidemiological techniques to gather biomedical and genetic information, as well as a broad range of more traditional psychosocial and behavioural measures for his studies. Dr. Caspi has a concurrent appointment at the Social Genetic and Developmental Psychiatry Research Centre at the Institute of Psychiatry at King's College London and at the Psychology Department at the University of Madison, Wisconsin. He's also involved in the Dunedin Multidisciplinary Health and Development Study in New Zealand. The titles of these research centres speak to the multi-discipline nature of Dr. Caspi's work and I think the locations to his love of travel. Long-term studies are the best way to study development, but they're not the easiest to plan or to conduct. Such projects often defy funding cycles and it's entirely possible that the project may extend beyond the career of one individual. You need to plan carefully before you start a programme that may take 10, 20 or even 50 years to come to fruition. It's really not easy to start over. So choosing the variables that may prove interesting in the future is a bit of a gamble. Fortunately for us, Dr. Caspi has chosen a very steady stream of interesting questions to follow. What is personality? Where does it come from? Does it change as we age? What influence does it have on our relationships and on our health? These questions cut to the core of our being and I think are the source of fascination for so many students of psychology. In addition, he asks many of society's tough questions about maltreatment, mental health, violence and criminal activity. Now it's easy to see that all of these questions have societal ramifications. Now whether you view science as above the fray of policy or in the thick of it, it is clear that informed citizens are more able to participate in the necessary policy debates. And so that we may all become better informed, please join with me in welcoming Dr. Ashlan Caspi. Thank you. This is in fact my second visit to Gustavus Adolphus. I was in the audience where you are seven years ago when my wife had the honor to deliver the John Kendall lecture here. We had a wonderful time and it's a privilege for me to be able to experience the gracious hospitality of the community and the college again. This is a first class act, so thank you. I have to admit, however, that I was a lot more relaxed sitting in the audience seven years ago than I am standing in front of it today. So let's all take a deep breath. The title of my talk, some of you may have recognized, is taken from a poem by William Wordsworth. And when the poet wrote this, he was saying that a child's character will shape who the child will be when he grows into an adult. Like the poet, like Wordsworth, we all think that we have a personality that defines us throughout our lives. Each of us believes that we have a unique personality. And what I'll try to do in this lecture is explore just how special it is in fact to have a personality. Specifically, what I'm going to do is try to tackle three questions. The first question that I'd like to ask and hopefully answer is what are the most important features of our personalities? Second, what are the origins of personality differences between people and how early can we tell what your personality will be like? Third, how early, or rather how do early emerging personality differences shape the course of our lives? In doing this and trying to answer these questions, I'm going to summarize some of my own work as well as the work of others. And if any of the topics that I present capture your imagination, you can write to me and I've given you my email address here. And I'll be happy to correspond with you, hopefully not all 3,500 of you, but just the curious ones please. Now, the foundation of all good science, including psychology, is measurement. And as a branch of psychology, personality research has the more specific goal of measuring personality differences between people. It's exactly for this reason that many consider Sir Francis Galton, the English scientist and statistician, to be the real father of personality psychology, equal to if not more so than say Freud or Bulby. For Galton claimed that the character which shapes our conduct is a definite and durable something and therefore it's reasonable to attempt to measure it. Now, this is not an easy task. English, we know, contains some 18,000 different terms that can be used to distinguish the behavior of one human being from that of another. But measuring personality turns out is not just a semantic nightmare. In fact, over the past 20 years, personality researchers have shown that the most important personality differences between people can be captured in five distinct traits. And I'll walk you through them. Openness to experience is a trait that describes the depth, complexity and quality of a person's mental and experiential life. Basically, whether a person is curious and open or narrow and closed-minded. And there are huge individual differences on this particular psychological trait of openness to experience. Conscientiousness, second trait, describes the extent and strength of impulse control. Whether a person is able to delay gratification in the service of more distant goals or is unable to modulate impulsive expression. Extroversion, describes the extent to which a person actively engages the world or avoids intense social experiences. Agreeableness, fourth trait, describes a person's intrapersonal nature on a continuum from warmth and compassion on the one extreme to antagonism at the other extreme. And finally, neuroticism, describes the extent to which a person experiences the world's threatening and distressing. Acrosticly, what you can see is that these five personality traits spell ocean, which is a convenient way of remembering what these traits are all about. And that describe the breadth of our personality as well. Now, these traits exist throughout the world. In different cultures, whether we look in Finland or in South Africa and in different language families, whether you go from Tagalog to Hebrew to English. This is an important discovery because if personality traits, think about it, represent variations in basic human ways of thinking, behaving and feeling, then the structure of personality should be universal across cultures. And it is, we can observe all of these five traits throughout the world in different cultures. These five traits can also be measured throughout the lifespan, starting in the elementary school years and into old age. And as a result of this, child psychologists, organizational psychologists, psychiatric geneticists and gerontologists have increasingly turned to these big five traits in order to make headway in understanding how personality develops and how it is that personality differences between people come to shape many consequential outcomes in our lives. And an important and perhaps the first question for developmental research is to ask what gives rise to these personality differences between people? Why do people vary on these big five traits from one another? The answer, and this shouldn't surprise you after two days, is nature and nurture. Now, that's a hardly satisfying answer. It'd also make for a very brief final lecture, wouldn't it? So let's take a closer look at just what it means to say that nature and nurture shape these individual differences between people. If we look at heritability, which refers to the proportion of personality variation between people that can be explained by genetic factors, what you can see in red is that 50% of the variance can be explained by the effects of multiple genes. This is true note for all big five traits for ocean as we go across. And these genetic effects, importantly, are uniformed the world over. In studies from the United States, from the United Kingdom, in Germany, throughout Scandinavia, even down in Australia, we get the same genetic effects, uniformity in the heritability of these traits throughout the world. In fact, to my knowledge, no personality trait reliably measured has ever shown no heritability. Now, the fact that personality traits are heritable should not surprise me. I've known about the heritability of behavior since man began domesticating and breeding animals. And as Ploman has already noted, it's unlikely that there are any single gene effects on personality. Rather, the genetic effects that we observe here represent more likely the sum of many genes or small genetic influences operating additively. I don't want to rehash all of that, but I do want to bring something else to your attention, which is that these estimates of heritability that have been presented here and that have been presented previously today and yesterday include not only genetic effects proper, but also they include gene by environment interactions. That is, genes are most likely to influence personality development not directly, but rather by exacerbating or by buffering environmental influences on development. And when we talk about these genetic effects on personality, what is in fact concealed in these estimates of additive genetic influences are also gene environment interactions. I'd like to turn for a moment to show you just how gene environment interactions work in shaping our personality. We recently demonstrated that one of the reasons not all maltreated children develop disagreeable and antagonistic or aggressive personalities is because of genetic differences between children. Let me walk you through this slide. We focused in our research on the MAOA gene, which encodes the MAOA enzyme, which metabolizes neurotransmitters that are involved in the stress response such as norepinephrine and serotonin, rendering these neurotransmitters inactive. And as you can see if you look on your left, maltreated boys who are shown here in the color red grew up to develop disagreeable and antagonistic personalities if they had a polymorphism right here of the gene which is associated with low MAOA activity. But if you look on your right what you'll see is that maltreated boys with a polymorphism or a variant of the MAOA gene which is associated with high MAOA activity were less likely to develop disagreeable and antagonistic personalities. To my knowledge what you're looking at right now is the first demonstration of a measured gene by environment interaction in psychology. And it's a finding, I tell you that not to boast, but rather to remind you that this finding needs to be replicated. But more generally if this is right and if this particular finding replicates, my bet in fact is that the most likely way the genetic effects operate in psychological development is in fact by not by shaping behavior directly but rather by influencing our sensitivity to environmental inputs just as we see in this particular study. Namely that not all children respond to maltreatment in the same way and the reason they do not appears to involve genetic differences between children. Over the next decade through the prudent use of genetic research, personality psychologists I think are poised to make great breakthroughs not because we're going to discover the gene for personality. There is no such thing. But rather because what we will increasingly learn is how genetic differences modulate the effects the environment has on our psychological development and that's where the exciting action is going to be. Now having said that we shouldn't lose sight of the earlier bar chart that I've now put back on the screen but what I've also done here is I've filled it up. What you can see in green is that above and beyond genetic effects and above and beyond the gene environment interactions that are subsumed in these heritabilities the environment does in fact make a huge contribution to personality development. And what research has demonstrated is that what matters most about the environment are the unique experiences that each of us has in our families. That is the reason we differ from our brothers and sisters is because we have different or non-shared, unique environmental experiences. For example birth order, what schools we attend, who we marry later on in life all offer critical and unique environmental experiences that shape our personalities and that increasingly serve to make us differ from our siblings. In addition how we are treated relative to our siblings is profoundly influential in shaping our personalities. It's relative treatment that oftentimes may be so influential in our development. And especially powerful methodology for documenting just how the environment shapes personality is to study monozygotic twins who are reared together. Monozygotic twins as you will have heard by now are genetically identical and therefore any differences between them that we see must be due to unique environmental experiences. In England we are now conducting a longitudinal study of twins. It's a nationwide study involving 2,000 twins. And in this study what we're doing is we're paying special attention to a unique environmental experience that children have expressed emotion in families. That is to study how emotional attitudes that parents direct at their children shape their children's psychological development. The way we do this is we conduct home visits with these families and during the course of the home visit which lasts about three hours we also audio tape the twins mothers when the children were in preschool talking about their children and we later code the content of these audio tapes. Now mothers in fact express wide-ranging attitudes towards their children certainly across families but what's also truly astonishing is the extent of differences that we observe within families in expressed emotion. And I want to give you a sense if I may of the variation in expressed emotion that a mother manifests towards her children. Prepare yourself for an English accent. Okay. Let's first listen. Oops. Is there a reason? Pat. Single left click. There you go. Let me try it again. Sorry about that. I can reboot. It's not worth rebooting. Trust me that there are huge differences in how mothers talk about their children. Okay. It's funny. And I should tell you a little bit about what happens with this mother because she's not especially unusual in what she has to say. But the description of one child involves basically an admission or an expression of profound hostility towards the child. The mother clearly says, I hate this child. She's a cow. And it's a terrifying thing to hear. And when you hear the other child being spoken about, she is described as my little butterfly, you know, who makes me so happy when she sings and dances around the house. We see these profound differences. And here they're exaggerating this particular family, the profound differences in what is expressed, the emotional attitudes that are expressed by mothers towards their children. But my point in all of this is that there's actually something very revealing about these differences that we observe within families, which is the differences in a mother's expressed emotions predict differences in her monozygotic twins development. And this is summarized in this slide where what you see is that our research shows that the monozygotic twin who received more maternal negativism shown here went on to become a more neurotic child according to teachers who rated the children's personalities when they entered school. So in short, what we're seeing here is that relative to our siblings, the way we are treated relative to our siblings, has a profound influence on our personality development. And that is the point of actually demonstrating this particular study to you, where we see again that the monozygotic twin averaged across 1,000 twin pairs that we have been studying. The monozygotic twin who received more maternal negativism goes on to become the more neurotic child according to teachers' ratings of that child. Now nature and nurture may shape our personalities, but an outstanding question for developmental research, and I think one that frankly most everyone in the audience probably wants to know the answer to is how early can we tell the origins of personality. And to find out we are going to take a trip to yet another country, we're going to go to New Zealand. And the reason we're going to go to New Zealand is because this is the home to the Dunedin study, which is a longitudinal investigation of all the babies born in the city of Dunedin in 1972 and 1973. And as you can see, the 1,000 members of this sample of all the babies born in one city have been assessed on a regular basis from birth, from their birth in 1972-73 until most recently age 26. And we're gearing up now for the next assessment, which will begin next year. At each age, the study members participate in a day-long program that involves physical, dental, and mental health assessments. What I want to do is just follow with you the sample over time to show you what a longitudinal study looks like. And here are two members of our longitudinal study, a boy and a girl, who were born on the same day in 1973. And here they are again when seen at age 3, at age 5, as 7-year-olds, as 9-year-olds, as 11-year-olds, as 13-year-olds. 13 was rough for all of us. So no smirks out there. As 15-year-olds, as 18-year-olds, as 21-year-olds, and most recently when we interviewed them at age 26. Now when the children were age 3, they were observed in a 90-minute testing situation that involved a set of cognitive and motor tasks. And following the testing session, the examiners rated each child's behavior, which allowed us to identify several different types of children, including one group of children that we called under-controlled. These were children who were distinguished from the remaining groups by their irritability, by their impulsivity, by their recklessness, really, in approaching the examiner and the toys and the tasks in the testing session. A second group of children we called inhibited. These children were distinguished primarily by their reserve and reticence in the presence of the unfamiliar, which was in fact often severe enough to interfere with their testing behavior. And a final group we called easy or well-adjusted. These are children who displayed some initial caution in the new situation, but they became friendly during the data collection session. They attempted to cope with difficult tasks, but they did not become too upset if the task was too difficult, and they were capable of reserve and control when it was demanded of them. The question is, do these behavioral styles at age 3 offer us any clues about what their personality is like in adulthood? What this next slide shows you is the answer to that question. These are the age 26 big 5 personality profiles of the three groups of children, 23 years later. Now if you look on your left, what you'll see is that under controlled three-year-old children grew up to be characterized by low agreeableness, by low conscientiousness, by high neuroticism, and by low openness to experience. Basically, they were aggressive, impulsive, high-strung, narrow-minded adults. In contrast, when you look at the inhibited children in the middle, these children grew up to be characterized by low extroversion, by high conscientiousness, which here means really high impulse control, and by low openness to experience. They were unassertive and uncontrolled, or over controlled rather. They were not fond of leadership roles. They did not like to take risks, and they were not very curious about the world around them. Finally, we have here the well-adjusted group, which is on your right. It's not that this group doesn't have a personality, but rather when you look smack down the middle, that is the average score for the sample at age 26. So well-adjusted three-year-olds basically grew up to define normal functioning, as reflected by their average personality scores in adulthood. What probabilistically, and I underscore probabilistically, these data show is that the child is the father of the man. Moreover, what happens is that personality differences continue to consolidate and to stabilize with age. And this is illustrated in a recent meta-analysis, which is a statistical method for quantifying the results of many, many different studies that have been conducted. Brent Roberts here analyzed all the longitudinal studies of personality ever conducted, involving 152 different studies based on over 50,000 research participants who have been studied for various segments of time, ranging from early childhood into old age. And here are the results where what I've done is I've plotted stability coefficients by age. The stability coefficients here range from zero, which essentially means total unpredictability of your personality from time one to time two to 1.0, which means perfect continuity, personality continuity over time. And what the results show is that our personalities do become increasingly more stable over time. Personality stability, in fact, increases from around 0.4 during the childhood years to 0.6 around age 30, and then reaches a plateau of 0.7 at age 50. Personality traits do continue to change a bit throughout adulthood, but after age 50, change is very, very rare. Sorry. Now, to me, in fact, the most surprising feature of these longitudinal data is that there is so much continuity and predictability in our lives and our personalities, despite the myriad changes in our lives. There's so much predictability in our personalities, despite the fact that we move, we marry, we bear children, we change jobs. Think of all the environmental changes that we experience and yet observe the impressive continuity in our personalities. How is it possible for there to be so much personality continuity amidst so much environmental change? Well, personality, cognitive and social psychologists have learned that this is possible in part because what we actually do is bring the world into harmony with our personalities. That is what we do in the course of our lives is that we create environments that reinforce our personalities. And this is achieved in three ways, through evocative, reactive and proactive effects, which I'm now going to discuss in turn. Evocative effects occur whenever an individual's personality evokes personality congruent reactions from other people. And this kind of evocative effect begins already very early in life. So, for example, infants who squirm and fuss when you pick them up will evoke a lot less nurturance from a parent than will an infant who likes to be cuddled. This kind of evocative effect, in fact, continues unabated throughout the life course. And one of the most important ways that our personalities shape our environment is because we actually display our personalities to other people. And indeed, our personalities are often expressed in our face and displayed in facial expressions of emotions. These expressions, such as disgust, anger, fear, can also be analyzed. And they can be analyzed using a system called the facial action coding system, which is an anatomically based system for measuring visually discernible facial movements. And several studies using very different populations, including some of our own research with adolescents, shows that different personalities do indeed display different facial expressions of emotion. Essentially, we may wear our heart on our sleeve, but we actually wear our personalities on our face. So, for example, what we know is that extroverts manifest facial expressions of emotion that tend to promote social contact expressions like enjoyment and amusement. That is what extroverts do is that they exhibit emotions that evoke friendliness and reinforce their very extroversion. Disagreeable persons are likely to manifest facial expressions of disgust and anger, and these in turn often cause other people to reject and dislike them, reinforcing their very disagreeable and antagonistic nature. And finally, the personality trait of neuroticism is associated with facial expressions that are indicative of distress, such as fear. The fact that our personalities are expressed in our face actually shouldn't surprise us. The etymology of personality after all is the Latin persona, which refers to the actor's mask that they wear. But the more important point that I wish to convey here is that one of the reasons personality is in fact so stable across the life course, is that each of us expresses our personalities in ways that can be readily perceived by others and in turn that are responded to in kind thereby reinforcing our habitual styles of communicating with the world. Reactive person environment affects a second way in which we bring the world into harmony with our personalities occur because individuals who are exposed to the same environment often experience it, interpret it and react to it differently. That is, people basically process the world around them in personality congruent ways. This is the basic idea that in fact during the latter part of the 20th century, united the concerns of personality psychology with cognitive psychology. So barring at that time from cognitive psychology, what many personality researchers did is conceive of people, of personalities, of social information processing machines. And personality is really what shapes the processing mechanisms. That is, what personality really does is it guides what we attend to, what we remember, and how we interpret. So if you consider for instance aggressive children, what we know is that when aggressive children try to resolve a conflict that they may have with another child, aggressive children are going to attend to considerably less information about the conflictual situation. They are also more likely after the conflict to remember all the more the insults and slights that have been directed at them. And they're more likely to interpret ambiguous situations in ways that are consistent with their personalities. So for example, if their stack of building blocks is knocked over, is accidentally knocked over, aggressive children are much more likely to interpret the situation as having been motivated by malice, whereas non-aggressive children are likely to think that it was probably just an accident. The point is that each of us extract a, if you will, subjective psychological environment from our objective surroundings. And it's that subjective environment that shapes our subsequent interaction with the world. And this is the basic phenomenological tenet of personality, that if people define situations as real, they are real in their consequences. Now just as cognitive psychology inspired a deeper understanding of the dynamics of personality in the latter part of the 20th century, neuroscience is now leading the way to a fuller understanding of personality in the 21st century. And in particular researchers are beginning to use functional magnetic resonance imaging to explore whether there are personality differences in what the brain responds to. The initial work is suggestive, but I think very intriguing. Most recently, Ken Lee and his colleagues examined brain reactivity to emotional stimuli. And what they had their research participants do here was watch alternative blocks of emotionally positive pictures, a puppy, and of emotionally negative pictures, namely a cemetery. And what the brain imaging results showed is that in different personalities, different parts of the brain were activated. And that's illustrated in the red segments of this slide, which show you the low size significant associations between the traits of extroversion, neuroticism, and brain reactivity in this instance to positive stimuli. And what you can see in the top row is that when extroverts saw positive pictures, for example, of the puppy, there was activation in select regions of their brain, in particular the amygdala. But this didn't happen when neurotic people shown on the bottom were shown emotionally positive pictures. So although they encountered the same objective situation, the brains of different personalities were in fact differently activated by different emotional stimuli. This is preliminary work, but what it does serve to illustrate is that personality differences are fundamental to the way we react to the world. And also, not so incidentally, I think this serves to demonstrate how new technologies can move us forward in understanding just exactly how this may be happening. Now a third process that promotes personality continuity involves proactive effects. And this occurs when individuals select or create environments that are congruent with their personalities. And this process can best account for two interesting interrelated facts about personality development, namely that with age, personality traits become both more heritable and more stable. And this happens in part because as we grow older, we can increasingly choose situations that are congruent with our personalities. As children age, they can move beyond the environments that are imposed on them by their parents and begin to select environments of their own choosing. And as adults live longer, they can increasingly fine tune their environments in ways that actually correspond more and more to their personalities. For example, we can change our homes, we can change our jobs, we can change our spouses so that these better suit our personalities. Now when we choose situations, that's not a prescription by the way, it's just an observation. When we choose situations that are congruent with our personalities, what we also do is we create situations that reinforce our personalities. And this is in fact most apparent in the case of marriage. In general, most people tend to choose marriage partners who are similar to themselves. This is called assortative mating and basically what it means is that birds of a feather flock together. And an important question is however what are the consequences of assortative mating? We had the opportunity to explore this question by studying a sample of 120 couples over a 10 year period. And what this slide shows you is that personality continuity was clearly related to assortative mating. That is the greater the couple similarity at the outset, here shown in red, among those are the more similar couples. The greater the continuity of their individual personalities over time. And this was true for both the females and the males in each couple. When people select situations, in the case of marriage, that are inhabited by people who are similar to themselves, what they also do is that they increase the likelihood that those situations will reinforce and sustain their personalities. Or for that matter, they will inhabit situations that do not call upon them to change. And this is a result of marrying here in this instance people who are similar to ourselves. Evocative reactive and proactive effects help us to understand in many ways how it's possible for there to be so much personality continuity amidst a sea of environmental change in our lives. These three effects also underscore the fact that the course of personality development is in fact a very conservative course. Our personalities are much better tuned for maintenance than they are for change. And in fact the three processes that I've just described not only impair people's ability to change in the natural course of their development, but these processes also make people very resistant to change because it is so hard to break up the harmony that we create, sometimes on purpose, sometimes inadvertently between our personalities and our world, for both bad but also good. And I'll return to that theme. Now, personality traits are not simply stable features of our lives. They also shape our lives. They shape the life course. And from adolescence to old age, our personality influences our relationships, our personality influences our work, and our personality influences our health. And what I want to do now is summarize which personality traits matter most for which life domain and why. Now, finding someone to love and hopefully someone who will reciprocate is one of the most important goals in our lives. And our personalities can in fact either facilitate or hinder the realization of that goal. Negative emotionality, which is the toxic combination of neuroticism and disagreeableness, is the strongest and most consistent personality predictor of poor relationship outcomes, including dissatisfaction, conflict, abuse, and breakup or dissolution. And we know this from longitudinal studies, long-term longitudinal studies that have followed samples of children. I have no idea why that's beeping there. And it's terrible that it's happening on abuse, isn't it? Anyway, we know this from long-term studies that have been following up samples of children into adulthood, as well as I said from shorter-term studies that have traced couples from the point of courtship through marriage. A rather dramatic illustration of the influence of personality comes from our own research, where we have been studying 360 couples in order to understand why some intimate relationships become physically violent. And it turns out that the personality combination of neuroticism and disagreeableness, what we call negative emotionality, is highly discriminating in this regard. If the man in the couple among the 360 couples we've been focusing on was characterized by negative emotionality, there was down the road several years later a four-fold increase that the relationship would become violent. Interestingly, if the woman was characterized by negative emotionality, there was also a four-fold increase that the relationship would become violent. And if both members of the couple had high negative emotionality, the risk of domestic violence was increased sevenfold. Now, I mentioned this last finding because although personality traits are rather powerful predictors of behavior, we in fact often forget that many social behaviors like domestic violence are the product or not simply the result of one person's personality, but the summed product of multiple personalities interacting with one another. The question is, how does negative emotionality exert its effect on our love lives? Well, this comes about through several ways. First, it comes about through assortative mating, the tendency to select similar partners. And we saw the consequences of assortative mating earlier in relation to personality continuity over time and how it in fact promotes the continuity of our personalities. And here, we just saw it again in the earlier slide, namely assortative mating for negative emotionality creates, if you will, a dangerous liaison with profound health consequences. Second, people high negative emotionality also react to their partners and trait congruent ways. And in particular, during conflict, high negative emotionality partners are much more physiologically reactive and they are more likely to escalate negative affect during arguments. Basically, small time conflicts easily get out of hand. And third, people high negative emotionality evoke behaviors from their partners that contribute to their relationship problems. So in his detailed studies of couples, John Gottman has discovered that high negative emotionality people express for detrimental behaviors, behaviors that are detrimental to the relationship, namely they criticize their partners more, they express more contempt to their partners in interacting with them, they're much more defensive, and they stonewall their partners. And in these three ways, okay, not these four ways, but in these three ways, negative emotionality creates the background against which relationships often flounder and love is lost. Let's turn to another domain in our lives to work. Personality traits from the domain of conscientiousness, remember ocean, right? From the sea, from the domain of conscientiousness are the most important non-cognitive predictors of educational achievement, of occupational attainment, and of job performance. That is, even after we take into account people's social background and their intellectual capital, what we know is that children who are conscientious, that is, planful, attentive, and persistent, grow up to fare better in a market economy. Added to this mix, there is evidence that positive emotionality, which is this pleasing combination of extroversion and agreeableness, predicts educational achievement as well as job performance, especially in managerial jobs and in jobs that involve working in groups. And finally, openness to experiences associated with more creativity in the workplace. Question is, how does personality affect all of these educational, vocational, and professional achievements? Well, first, what we have to remember is that although we have some say in what kind of work we do, most of us are also selectively recruited into our jobs by virtues of our personalities. And such recruitment effects mean that some personalities are in turn more likely to succeed than others. And in this regard, it's important to remember how evocative effects work or operate. So research shows us that teachers do in fact devote more time and energy to extroverted and agreeable children because these children are more enjoyable to spend time with. And all other things being equal, employers do preferentially hire and promote extroverted and agreeable individuals. And that's how recruitment effects of personality into better positions and into greater achievement tend to work. Recruitment effects are complemented further by expulsion effects. Basically, workers are also released and dismissed from jobs because of their personalities. And these two processes, recruitment and expulsion, are interesting because they can also account for social mobility across generations. That is for why some children surpass their parents' social class and why other children do not. Here, what I've put up are the results from a longitudinal study where we studied two generations. And what we showed is that children who were disagreeable and low on conscientiousness, the children in yellow, achieved less than their fathers did, whereas children who were agreeable and conscientious achieved as they moved into adulthood more than their fathers did. We've heard mention of the fact that social class does shape many important outcomes in our lives. And in fact it does. It is equally important to remember that our personalities often shape our social class standing. And that's what this particular analysis shows you over two generations. And here this happened because children in yellow were recruited into bad jobs and could not also hold on even to those jobs. That is because of recruitment effects and expulsion effects operating over time. Finally, our personalities shape our work lives because they influence how we perform on the job and how we solve problems. In some instances I think this is quite obvious. For example, conscientious people are simply better organized and can solve problems more efficiently. But there are also some surprises about how personality influences what we do in the workplace. For instance, research shows that people who are extroverted and agreeable, that combination that I keep referring to is the pleasing combination of positive emotionality. These people are more flexible and they can think outside the box whereas people low on positive emotionality freeze on initial decisions and have a harder time thinking divergently. This is in fact one of the great virtues and functions of positive emotionality independent of IQ. Finally, I want to turn to health as another life domain to focus on. The best evidence that we have is that personality affects our health or the personality affects on our health. The best evidence we have come from life span studies in fact, studies that have followed samples of children from the first decade of life into old age. What these studies document quite clearly is that the personality trait of conscientiousness predicts longevity. For example, evidence from the term life cycle study which first assessed children in the 1920s, some 80 years ago, shows that even after taking into account their social and economic background, conscientious children, and these children here are shown in blue, those children who were prudent, planful, persistent and dependable, lived longer to an older age than children low on conscientiousness. In addition, personality traits related to disagreeableness are associated with greater risk of disease and this is most apparent in relation to anger and hostility. For example, a follow-up study of 1,000 young men revealed that those men in yellow who displayed the most anger in their early 20s were the most likely to suffer from cardiovascular disease, especially from premature cardiovascular disease that is disease occurring before the age of 55. Finally, we have the evidence concerning neuroticism in ill health and this evidence is rather mixed because in fact what research and health psychology shows is that neuroticism appears to be related to health complaints but not necessarily to symptomatology. And I'll show you some evidence about this in our own work. What we have found is that neurotic people are significantly more likely to report suffering from allergies and this you can clearly see on your left which shows that neurotic people simply report many more allergies. But if you look on your right, what you see is what happens when we tested them for various allergies via skin prick test. Basically we found no evidence whatsoever that neurotic people suffered adverse reactions to numerous allergens, dust, cat, horse, cladosporium and so forth. Neuroticism appears to dispose people to perceive health problems and to complain about those problems but it doesn't necessarily appear to be associated with measurable ill health. How does personality affect our health? This happens through at least three ways. First, some personality traits are in fact associated with a higher concentration of unhealthy lifestyles. Based on personality testing and some of our longitudinal work, we've identified in fact a group of adolescents who we consider to have health risk personalities. These are adolescents who were highly disagreeable, high on disagreeableness and low on conscientiousness. And when we followed these adolescents over an eight-year period, we found that they were four times more likely than other adolescents to smoke. There were two times more likely to drink and drive. There were three times more likely to engage in unprotected sex with multiple partners and there were five times more likely to get into fights. So apparently some adolescents gravitate toward lifestyles that compromise their adult health, that increase their risk of injury, that increase their respiratory ailments and that increase their risk of infectious disease. Second, some personality traits are related to pathogenesis, that is to mechanisms that actually promote disease. And this is most apparent in the case of the personality trait of hostility, a facet of disagreeableness. Let's look at the men in yellow in this particular slide. These are highly disagreeable and hostile men in yellow here. And when these men with this slide shows you were harassed, in this case these men were harassed as part of an experiment in which participants were harassed by a technician while they were asked to solve a puzzle. Hostile men in yellow showed large increases in heart rate and in blood pressure. That is disagreeable and hostile men show physiological hyper-responsivity to stress, but we do not see this reaction among men low in hostility. So apparently even relatively simple stressors evoke excessive sympathetic nervous system activity in hostile men, but not in non-hostile men. And it's this way in which personality is implicated or personality traits are related to pathogenesis to the mechanisms that promote disease. And finally, personality traits also affect how people react to illness and influence whether or not people adhere to recommended treatment programs. For example, research on tobacco dependence in fact shows that neurotic and disagreeable people, that is people high in negative emotionality, are three times more likely to relapse following participation and smoking secession treatments than are people without this personality profile. Personality traits affect not only how we react to a particular illness or in this instance whether or not people choose to or can adhere to particular recommended treatments. So apparently whether or not here one chooses to adhere to treatment is shaped by personality traits. In fact, future research on personality and health is probably one of the most exciting areas in the field of personality today. In terms of basic science, we need to delineate much more completely the path of physiological mechanisms by which personality affects health. And in terms of health care delivery, what we're now doing is actually reaching a point where we can begin to develop better targeted behavioral interventions that are based on psychological profiling of patient factors. Well, William Wordsworth, our poet, claimed that the child is father of the man. As a good hypothesis that he had and psychological research, longitudinal studies have, I think on the whole, proven him right. But I don't want this to be a bummer talk at the end of these magnificent two days, so I don't want you to despair. Although the child is father of the man, it's no reason to walk out of here hanging your head. First, although changing personality is hard, you will note that what I've tried to show you is that you can change how personality propagates itself over time. Second, although you may not have been able to choose your personality, you can control many outcomes in your life by changing what is not influenced by your personality. And third, although you can't make people what they're not, you can't channel what they are, as parents, teachers, into the most rewarding, satisfying and productive directions they can possibly go. And finally, let me leave you with a thought which is how terrifying and chaotic our lives would in fact be if our personalities were unpredictable to ourselves and to others across time. In fact, the last three lines of the poem by Wordsworth read, The child is father of the man, and I could wish my days to be bound to each other by natural piety. Thank you. We'll invite our panelists up for one last time. Again, if you have questions, would you please give them to the ushers, and we'll see if we can do a few of them here. Thank you, Jerry. I don't think you succeeded in dispelling our humor at the end, though. Aww. So we're going to somehow optimize these people who are so angry, disagreeable. Bring out whatever good traits are possible when you're angry and dissuade them. I think I'll wait just a minute. Okay, I think we'll begin. For those of you who are leaving, we'd appreciate it if you could keep the noise down so that we can hear the questions here. We'll begin by asking if the panels would have any comments or questions for Dr. Caspi. I have a wonderful talk. I just have one question, and that would be the premise that those are the five universals. I mean, if you think about history and think about cultures, I would think that if I were in classic China and I was a personality researcher, that loyalty to the family would be one of the big five. And if I were in another place, if I were the Yanamama, I might think that high energy. In other words, I know that the data you report are absolutely right. And when you give those questionnaires and do the factor analyses, those are the five factors. But you know as well as I do that that's a very specific source of evidence. And so I guess the question is, don't you think there is a bit of parochialism that doesn't take into account the enormous variety in human variation across history and culture, which in some cultures there can't be much variation in some of those five. That's my point. Let me share an anecdote with all of you before I try to answer that Jerry Kagan's question. My first job was at Harvard, an assistant professor in 1986, and my first assignment was to teach introductions to psychology, and I was to co-teach it with Jerry Kagan. And he was excellent. Jerry called me into his office and he said in his inimitable way, Av, Av, Av, what are we going to do? I looked at him blankly and he said, tell you what, you tell me what you want to teach, what you think you know, and I'll do the rest. I've dared not challenge Jerry Kagan since that day. Evolutionary psychologists have suggested that the reason these five traits exist in all languages and in all cultures is because these traits somehow capture adaptive problems that were confronted by ancestral human populations. And that's why we see these five traits emerging in all cultures. I'm not entirely happy with that answer probably because I'm not sure if it's really terribly testable. And I do fully agree that the big five do not provide a complete or understanding or sufficient information about personality. Human personality is both more nuanced and much more interesting than suggested by these five global traits. What the big five then is not all there is to personality, but rather what they are is the broadest and most general way that we have available for describing people. There will be variations across cultures and how personality, these personality traits may be expressed. We can think of this as kind of intra-cultural differences. That is there will be unique expressions of personality traits in different cultures. Likewise, there are inter-cultural differences, that is there are average differences in traits across cultures. What I've tried to emphasize in the slide in which we had stars that appeared throughout the world is a third question, which is a transcultural question. Are there human universals in trait structure? And the answer to that appears to be yes. And that is at least a good starting point that we have at the most broad and general way for describing people. Dr. Rappapur? Yes, that was a wonderful talk. And I was looking at your statistics about consistency of personality across ages. And Mike, I have a reaction a little bit the way Eleanor's reaction was when she sees, let's say, a 60% concordance rate in monozygotic twins. And she wonders about, well, what about the discordant ones? I have something of the same rate. You had high consistency, but not that high. And I wondered even at an anecdotal level if you'd looked at who are the ones that seem to have changed personalities and what you made of that. This may be wishful thinking, but I'm eager to know. Sorry, everyone can see me out there as I'm thinking. The reason I'm pausing here is because embedded in your question are actually two separate questions. One is a question about effect sizes or the magnitude of the consistency across time. And the other is a question really about change. So let me go to the first one first. How big does the continuity have to be in order for us to be impressed that it's big? The answer I guess has multiple parts to it. First of all, even small effect sizes are very meaningful and are very practical. Let me sort of work backwards here. Epidemiological and clinical studies repeatedly uncover associations whose effect sizes are between, say, 0.1 and 0.3. And that upper bound is exactly the type of consistencies that we've observed between age 3 and age 26. Many people would say, well, gosh, that's awfully small. That's not very meaningful. But those are, in fact, the associations, for example, that we observe between decreased bone mineral density and hip fractures, between nicotine patch and smoking abstinence. What I'm simply trying to say is that these coefficients may not appear awfully big to many of us, but let's just pause for a moment and consider the fact that, in fact, much of our life, and much of the regimens that we follow, because our doctors tell us to, are actually based on precisely that evidence base. So if you're taking care with a bone, you know, or concerned about bone mineral, or are actually trying to stop smoking, the reason you're doing so is because if you don't, those are about the same kinds of effect sizes that you'll observe down the road in terms of ill health. I guess that's point number one. Point number two is that although we see predictive associations at any point in time here that are relatively small, note that what I'm actually doing is just showing you correlations between one trait and one outcome. That's not the way the world works. Cardiovascular disease is not simply shaped by hostility. It's a multifactorial illness that is shaped by multiple factors, including multiple personality traits. So it is not, I think, correct to infer that the effects are small, simply because there's an association between one trait and an outcome that is small. Third, we have to remember that the effects of personality accumulate over time. Although most of us who do longitudinal research follow people up across multiple situations and across multiple ages, the way we actually look at our data, in fact, the way I've shown you much of the data from my studies, from other people's studies, has been to link one point in time with another point in time. And what that tends to do is it, in fact, is it tends to underplay, to minimize the extent of connectedness in development, because the contribution of personality from early life to later life is not in predicting a single outcome at a single point in time, but is in predicting cumulative outcomes. So consider an analogy. Differences between baseball players are trivial if you consider them on the basis of a single at bat, but they become much more meaningful over the course of a game, over the course of a season, over the course of a career. And that's how we vote, or well we don't, but whoever votes for the Hall of Fame makes the decisions on the basis of a whole career, not on the basis of a single at bat. So there are cumulative effects that are, in fact, much stronger than what we simply see here. Now, the second part of your question is about change. I'm positive that's going to come up in these other questions. So can I defer on that? Okay, can I come in here? I'm really fascinated by this universal trait structure and what it can mean. If I understand it, it means that every society that's been studied has some people who are higher than others in anger and disagreeableness. Others who are high in agreeableness and conscientiousness and so on. You would think that disagreeableness and neuroticism would drop out if it leads to shorter lives and more heart disease and being avoided by others and bad marriages and all these things. And yet that's been maintained in all these societies and it just makes me wonder, does every society need to have within it some conscientious people, some warriors? It's very curious. Could you please comment? Would it be great to say just yes or no? The answer is that these traits are not necessarily maladaptive. At any given point in time in any given period of history they may be associated with maladaptive outcomes but they may also be associated with many adaptive outcomes. In fact, if you really want to think about it with disagreeableness, sure it may be, hostility may be associated with premature or coronary heart disease but these are also the same people who marry more women and sire more children. So I mean that's sort of one answer to how it propagates. So I suppose that's actually the answer to why over generations it hasn't been eliminated. You win. All right, we have some questions here. We must have a number of professionals in the audience here. Do you believe that a trauma like rape or loss of loved one will change a personality? How about at or after the age of 50? I believe that it will change a personality. I believe that it can have a profoundly damaging effect on our health. Yes. Okay. Let me add to that. I also know from the empirical evidence that not all people respond to trauma in the same way and that's the important caveat here. And some personalities do in fact respond, are much more vulnerable to traumas than others. What are the predominant processes involved, genetic or environmental, when individuals do undergo some kind of profound personality change? Do that again. This is why I gave you my email by the way so I could just write to you. One of the questions was would you please repeat your email address? So we'll do that before the end here. All right, what are the predominant processes involved? Are they genetic or environmental? When individuals do undergo a profound personality change? If there is a profound personality changes due to genetic changes or environmental factors? I mean that's interesting because I think it goes back to the earlier question and in fact is a better answer to that or to the question previous to that is a better answer than the one I gave, which is both. You have both the trauma but also personality differences that are in part heritable that affect the response to the trauma. So the answer is at least in theory what we should be seeing is gene environment interactions in relation to that and I think that was exactly where I was going with the study on the MAOA differences in response to childhood maltreatment. Now here's one for the teachers in the audience. Please elaborate on how teachers can help a disagreeable neurotic children be shaped positively if you can't change them fundamentally. Well you know I'm not a parent and I've not been a very good teacher all the time. One of the hardest things about teaching different personalities, teaching different children, is that you often really have to suspend your own personality in order to deal with multiple personalities with other multiple children and by that I mean that there are instances in which one really does need to tailor the kinds of activities that we provide to children in the classroom in order to get compliance from the children, in order to get children to focus, in order to get children to concentrate. The difficulty that I think that most teachers have is again to suspend their own personality, their tendency to respond to the world in the same way and instead to focus on each child as an individual personality. The question with regards to this side, the child who is high in negative emotionality is not a prescription that is not too different from how one would structure educational settings for hyperactive children. Because in fact those two qualities, that negative emotionality is in fact one of the personality traits that we know is much more elevated among hyperactive children. Now here's one that comes out of the corporate environment. It says, are the types of personality tips currently popular in corporate enrichment training? For example, smile even if you don't feel like it. Is this useful? Don't people pick up on the fact that a person isn't projecting their genuine personality? It's an excellent question and the answer is yes. We can easily detect the false smile. There are actually very interesting differences in the musculature that is involved in a genuine smile and in a false smile and people can detect those differences. I don't think that you can actually simply train people to smile differently but you can actually, I think, do a fairly good job learning to modulate your emotional expressions. My wife's tried to get me to do that for years. Alright, here's one from the psychologist here. If personality doesn't change much over time, how are we clinicians able to help produce positive changes in our patients' lives and a corollary question here says, cognitive psychotherapy claims to be able to change negativity, pessimism to positive thought. Is this possible and to what degree? Different therapies have different goals. I think the best evidence that we have for effective treatments has to do with trying to alter the kinds of role behaviors that we perform inadequately in our lives. It has to do with trying to make people aware of particular cycles in which they easily get trapped and that elicit reactions from other people in unhealthy situations in ways. I don't think that actually many therapeutic programs do a very good job changing personality traits. What they can do is an excellent job in changing how we enact particular roles in the course of our lives in ways that make us more pleasant to be around. But I don't think that the evidence actually exists out there and I know that I'm not going to make many people happy here, especially the clinicians in the audience, but I don't think that there's actually very solid evidence for deep seated personality change in the course of psychotherapy. Just a couple more questions here. This one says fantastic speech. I agree. Do differences in culture predict how factors vary from country to country? Do they vary by culture, for example, Japanese compared to American? Yes, and this is a fascinating area in cross-cultural research. Thank you for saying that, by the way. Fantastic. Cross-cultural research has many different purposes. To me, in fact, I think the most interesting part of cross-cultural research is not to go on and ask whether or not these universals and traits exist throughout the world and in different cultures, but really to understand how the same traits have different expressions in different cultures. There's another one. Was the drop in the stability graph at age 49, the midlife crisis? That's good. I actually think it was just a little blip in the data because there aren't as many observations that went into the meta-analysis in that particular analysis. All right. Well, if you like that one, wait till this one. It was once postulated that old people become weird. Does your work not suggest that it was more likely that weird people become old? Very good. I think I'll pass on that one. I think we probably have just about exhausted our panel here. I think what I would like to do here is to thank you all for coming, and I would really like to thank all of my panelists here. I think a person that I ran into in the audience summed it up best. He said it was absolutely amazing how folks were managing to talk about 12, 20, 40 years of research and to somehow or another crystallize that into a 40-minute talk that actually most of us could understand. And this audience is beautiful. Thank you very much for coming. Have a safe trip home.