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Chapter 1 The Science of Personality A brother and sister look through a magnifying glass. © Mike Powell/Digital Vision/Thinkstock Learning Objectives After reading this chapter, you should be able to: Describe the beginning of personality psychology. Define personality and distinguish among the related terms of character, trait, factor, temperament, and mood states. Understand the importance of theory construction as it is related to personality psychology Explain the importance of using scientific methodology in the study of personality. Identify and describe ways to assess and measure data and research. Identify and describe the tools and methods used to collect data and conduct research. Be familiar with some of the ethical issues related to psychological testing. Introduction A judge is trying to determine whether a defendant is criminally insane. You read about a celebrity who can't seem to stop using drugs and getting into legal trouble and wonder what it is about their character that leads to the repeating of such mistakes. You wonder what makes people go out of their way to be kind or rude. Major corporations try to identify the best leaders to hire or employees that will stay with the company for a long time. Each of these questions (and many more) fall within the domain of personality psychology. However, there is a lot more to addressing these issues than simply formulating an opinion as to the answers. Theories can be developed and scientific studies designed to test the theories and maximize the prediction of outcomes. That is in essence the science of personality. In this chapter, the focus will be on how the scientific method is applied to the study of personality and how it has resulted in the development of a wide range of theoretical models. 1.1 Why Study Personality? An Overview of the Major Theories Christopher Dorner in a camouflage, Navy issue shirt, smiling and posing in front of an American flag. Getty Image News/Getty Images Christopher Dorner, former LA police officer who gunned down fellow officers and was subsequently killed. In your everyday life, opportunities arise for you to consider the uniqueness of others. Sometimes you have an encounter that leaves you wondering why an individual would choose to act kind or meanspirited. At times, we are even unsure as to the reasoning behind our own behavior. Although it is certainly rational to consider the role of situations in explaining behavior, it is also reasonable to consider the role of the individual's character to explain and predict important outcomes. Indeed, of particular interest is the interaction between the situational influences and individual differences (also known as personality). This text is dedicated to examining personality and the important theoretical, research, and applied questions that emerge from its study. Of course, a broad range of societal issues tend to grab our attention, especially high-profile criminal behavior, but regardless of the topic, it is typical for societal questions or problems to motivate the application of personality theory to real-world issues. Christopher Dorner, for example, was a former LA police officer who had also served in the Navy. He allegedly gunned down three fellow officers, apparently motivated by revenge for grievances related to his dismissal from the police force. After several killings and a Facebook manifesto riddled with threats, a massive manhunt ensued. Dorner was subsequently found, surrounded, and killed. Fortunately, such violent responses from disgruntled employees are relatively rare, even among the ranks of former police officers and those with military backgrounds. Thus, it is reasonable to ask what caused Dorner to act as he did—and can we predict and alter such behavior? This text will provide an overview of some of the major theories of personality, along with research that in some instances supports, and in other instances fails to support, aspects of those theories. Here is an overview of some of the dominant theoretical accounts of personality and how they might be applied to Dorner. Theoretical Perspectives on Personality There are seven primary schools of thought with regard to personality: psychodynamic neurobiological behavioral cognitive/social interpersonal/relational trait self-psychology (humanism/existentialism) Each of these perspectives is covered in detail in the chapters of this text. Here, we present a brief introduction to each view and how they might apply to the case of Christopher Dorner. For a list of general treatment considerations for the different perspectives, see Table 1.1. Psychodynamic Perspective Beyond the Text: Classic Writings Freud had a great deal to say about psychopathology, even suggesting that seemingly benign behaviors could be interpreted as problematic. Click here to read The Psychopathology of Everday Life (1901). Reference: Freud, S. (1901). The Psychopathology of Everyday Life. London: T. Fisher Unwin. Retrieved from http://psychclassics.yorku. ca/Freud/Psycho/ Psychodynamic theory, which was largely formulated by Sigmund Freud, suggests that we are driven to act by instincts that are sexual and aggressive in nature. This perspective suggests that we are constantly in conflict with ourselves and society. The theory posits that the rationale for all adult action can be traced back to how we related to our parents. Most importantly, the theory argues that the presence and exact nature of our motives (i.e., why we act in certain ways) is unknown to us. Was Dorner preoccupied with acceptance by his parents? Did he have a conflict-ridden relationship with his father, resulting in the "transference" of blame toward other authority figures? This perspective would also assume that Dorner would have little knowledge or insight as to the true motives behind his actions. Neurobiological Perspective One of the primary contributors to this perspective on personality was Hans Eysenck. He viewed humans as biosocial animals, and he sought to link the social and biological sciences within his theoretical framework. Eysenck suggested that the cause of behavior could be traced to brain functions; he focused specifically on differences in brain activation. For example, he believed that the ascending reticular activating system was the brain structure responsible for the manifestation of extraverted or introverted behavior. Significant advances in this perspective have been achieved with the advent of high resolution imaging techniques. Did Dorner have some basic brain structural or neurochemical problem that would have resulted in the incidence of impulsive and aggressive behavior? Was Dorner biologically predisposed to violence based on the presence of aggressive behavior in his ancestors? Beyond the Text: Classic Writings Watson wrote a classic paper that applies behaviorism to mental disease. Not surprisingly, he focuses largely on behavioral manifestations, but this is an important starting point. Click here to read Behavior and the Concept of Mental Disease. Reference: Watson, J. B. (1916). Behavior and the concept of mental disease. Journal of Philosophy, Psychology and Scientific Methods, 13(22), 589–597. Retrieved from http://psychclassics.yorku. ca/Watson/mental.htm Behavioral Perspective Rooted heavily in empiricism, the behavioral perspective has been influenced by the works of John Watson, Burrhus Skinner, John Dollard, and Neal Miller, to name a few. This perspective emphasizes the role of learning in personality; that is, it focuses on how we connect certain stimuli with specific behavioral responses. The concept of conditioning is especially central to this perspective, and much of the research is based on animal models (i.e., it was assumed that basic learning principles can be applied to all species of life). Was Dorner reinforced for violent behavior in his upbringing or, more recently, was he given attention for his extreme actions? Did he come to equate, through conditioning, the fear he instilled with the respect he demanded from his colleagues? Cognitive/Social Learning Perspective This perspective was informed by such individuals as Albert Bandura, Julian Rotter, and George Kelly. The cognitive perspective emphasizes how individuals uniquely perceive, interpret and recall events in their lives, and how this can shape their character. That is, this perspective highlights the importance of how reality is constructed by an individual, rather than being determined by an objective reality. The cognitive perspective has also been closely linked to social learning theory, which focuses on learning through modeling (i.e., observing the behavior of others). Beyond the Text: Classic Writings Bandura and colleagues have specifically studied how aggressive behavior in children is repeated after it is modeled for someone. Modern research has largely confirmed these findings, even for adults, and here you can read one of the first classic publications in this area. Click here to read one of his papers on modeling. Reference: Bandura, A., Ross, D., & Ross, S. A. (1961). Transmission of aggression through imitation of aggressive models. The Journal of Abnormal and Social Psychology, 63(3), 575–582. Retrieved from http://psychclassics.yorku. ca/Bandura/bobo.htm Had Dorner been exposed to examples of violent behavior in his own home or in popular media, and so he simply mimicked what he saw? What was his unique way of interpreting the events that led up to the killings and his own death? Interpersonal/Relational Perspective The interpersonal perspective emphasizes how interactions with others, especially dyadic interactions, drive personality. This is a departure from theories that largely focus on the individual because the focus is on the interaction with others. This approach includes the works of Harry Sullivan, Henry Murray, and Murray Bowen. Relationships, including relationships that may be more artificial in nature (such as the one that a patient might have with a therapist), are the primary focus, and these theorists think that they undergird personality development. Were Dorner's relationships with his former colleagues marked by deviant exchanges, during which he experienced confusing and contradictory emotions? Did he have problematic interactions with authority figures in his life? Table 1.1: Treatment considerations for theoretical perspectives Theoretical perspective Approaches for treatment Psychodynamic theory Can conflict in parent-child relationships be used to predict who has the greatest propensity for violent behavior as an adult? Can we intervene with therapy in the family of origin to minimize aggressive behavior later in life? Can making an individual aware of unconscious conflict allow that individual to redirect aggression toward safer, more appropriate expressions? Neurobiological Can the presence of neurochemical or neurostructural abnormalities be accurately detected? Can those with such problems be identified and treated to minimize aggressive behavior later in life? Behavioral Can token economies be employed to help individuals value prosocial, rather than antisocial, behavior? Can individuals who are engaging in aversive behavior be reconditioned to demonstrate more socially acceptable behavior? Cognitive/social learning Can long-term exposure to violence in television, movies, video games, and other forms of media entertainment predict the incidence of violence, and can we curb such violence by minimizing exposure? Is it possible to intervene by helping individuals interpret events differently (i.e., in a more favorable light)? Interpersonal/relational Can we examine an individual's interpersonal style with others to identify signs of problematic behavior? Is an individual routinely involved in attempts to control and blame others? Could complementary relationships be used to alter the structure of more problematic relationships? Trait Can the personality traits that predict the incidence of various forms of mental illness or violent and aggressive behavior be detected? Can we find more adaptive outlets for these traits? Self-psychology (human/existential) If an individual is provided with support and acceptance, is violence, or even the thought of violence, mitigated? Are feelings of isolation the root of anxiety and other disorders, and do feelings of isolation exacerbate extremist thinking? Trait Perspective The trait perspective has had many significant contributors, including Gordon Allport and Raymond Cattell in the early years and researchers such as Paul Costa and Robert McCrae more recently. This perspective assumes that there is a broad framework for organizing traits, which are essentially descriptive terms or labels used to characterize a person's personality. Trait theorists focus largely on measuring traits, understanding the associations between them, and investigating their underlying causes (most typically linked to biological mechanisms). In order to help organize the great many traits that have been employed to describe human behavior, researchers in this area have used advanced statistical techniques, such as factor analysis. In many ways, traits also represent the vernacular most used by lay individuals when describing personality. What traits would have made Dorner most susceptible to turning to violence? Did he have a longstanding tendency for violence or aggression that could have been predicted from other traits, such as dominance or poor frustration tolerance? Self-Psychology (Humanistic/Existential) Perspective This perspective reflects an attempt to conceptualize human behavior in a more favorable light, emphasizing our tendencies for growth, achieving our highest potential (ideal self), and understanding our existence (why we are here). Key early contributors included Carl Rogers, Abraham Maslow, and Rollo May. More recently, the positive psychology movement, which is dedicated to building thriving individuals and communities, has represented a resurgence of this perspective. Was Dorner feeling powerless until he began to take matters into his own hands by killing others and drawing attention to his cause? Had Dorner lost the ability to value life? Had he been placed in a situation where those around him only valued him if he engaged in specific behaviors? These general theoretical applications establish a framework upon which more specific questions can emerge. There are also important questions that can be applied to all perspectives. For example, to what extent was Dorner fully aware of his actions and their consequences? Was there anything that could have been done to intervene and alter Dorner's behavior? Was there a point in the sequence of events leading up to the first shooting after which no intervention was possible? Contemporary personality theorists and researchers provide us with a scientific basis to understand the most essential questions in life. The goal of this text is to not only demonstrate the importance of these questions, but more importantly, to establish a structure for how to optimally frame the questions and how to devise the best way to scientifically answer them. The Early Beginnings of Personality Theory Qualitative vs. Quantitative Research Critical Thinking Questions: How are qualitative and quantitative methods different? What are some of the advantages and disadvantages of qualitative and quantitative methods? The earliest pioneers of scientific work that has been associated with the field of psychology include Wilhelm Wundt, who used quantitative methods in studying perceptions, sensations, cognitions, and feelings. He considered these the "atoms" of conscious experience and thought that by understanding them he would understand the structure of the mind—hence the label structuralism for his school of thought. William James considered psychology to be a natural science and was largely responsible for introducing experimental psychology to the United States. However, the field of personality psychology began to coalesce in the 1930s, with the publication in 1937 of Gordon Allport's Personality: A Psychological Interpretation. During this same decade, the journal Character and Personality was established, which was one of the first psychology journals to use the term personality in its name, and the comprehensive works of Kurt Lewin and Henry Murray, two of the founding fathers of contemporary personality research, were published. Although individuals, such as Sigmund Freud and William James, whose life work would later be included in the personality domain, predated this time period, it was in the 1930s that the specialization of personality psychology emerged, growing out of the primary area of clinical psychology (see also Barenbaum & Winter, 2013). The earliest roots of personality theory emerged from clinical experience. Indeed, much of what we have come to understand about personality comes from clinical observation and psychometric testing of individuals with disordered personalities (abnormal psychology or psychopathology). Clinical observations, in the form of thousands of published case summaries, make up the foundation of some of the more well-known theories of personality, and these theories have contributed to the current system of classification of mental disorders. The understanding and advancement of personality theory is inextricably linked to developments in the field of psychotherapy, and a wide range of models have been proposed to explain the association between these two fields (see Mayer, 2004). Psychotherapy became a branch of psychology during the 20th century, and the birth of modern psychotherapy can be traced to Freud's developing a comprehensive theory of psychic functioning. Moreover, many important personality theorists were psychiatrists (Freud, Jung, Sullivan) or clinical psychologists (Carl Rogers, George Kelly). This resulted in a marriage between psychotherapy, one branch of clinical science, and the study of what makes us unique. The clinical perspective continues to be an important lens through which to view personality, largely because clinical work is concerned with behavior or personality change. Psychotherapy has traditionally provided one means of observing, measuring, diagnosing, and treating personality and related disturbances. However, personality is also relevant to nonclinical functioning, and has more recently been associated with the positive psychology movement, reflecting the optimal experience of life (e.g., Sheldeon, Kashdan, & Steger, 2011). In this respect, modern personality psychology is much broader than its predecessor, as it has been applied to all aspects of human experience. Applying Science to Personality Although humans have been conducting experiments in various less formal ways since appearing on the earth, it isn't until recent history that science has become more widely accepted (Lathrop, 1969). Science presents ways of experimenting that are potentially far less costly and more efficient than our primitive "trial and error" methods. Gordon Allport was one of the first to focus on the study of the personality, though his biggest contribution was not so much what would be the target of study in personality psychology, but, more importantly, how it would be studied. Allport advocated a clear shift toward studying the individual person within a social science framework (see Allport, 1937). The term personology, which was coined by Murray (1938), refers to the development of theoretical systems for explaining and understanding human behavior. As examples, consider the theoretical perspectives briefly introduced in this chapter that were used to explain the behavior of Christopher Dorner. These diverse theories offer markedly different explanatory frameworks for the same observations, and they emphasize different factors. Psychologists or social scientists who engaged in personology were identified as personologists. Murray specified that the methods of personologists are those of science, in that they make systematic observations and use scientific methods to test hypotheses. Although the term personology is used less frequently today, an emphasis on scientific methods remains central to the field (see Section 1.4, "The Scientific Method," for more details). Theoretical systems are generally based on scientifically established constructs. A construct is a tool—usually a concept, model, or idea—that is useful for organizing observations and making them meaningful. For example, conditioning is a construct (a model) that is used to understand various forms of learning. An important construct for understanding both normal and abnormal human behavior, the central subject of this volume, is the concept we know as personality (and, in pathological versions, personality disorders or dysfunctions). Personality theorists study personality using tools of psychological science to assist in the development of theoretical paradigms, or models, that attempt to explain human behavior. Researchers have developed a variety of theoretical models, reflecting their different perspectives, to explain how personality operates. These theories will be discussed in the chapters of this text, along with the scientific research used to establish, evaluate, and expand those theories. This first chapter will also introduce you to some of the primary scientific methods employed by researchers in this field. 1.2 Defining Personality The term personalityis a well-established part of everyday speech. Countless popular magazines feature articles about personality, promising to help us learn how to deal with difficult people, how to live with those who have personality disorders, how to become leaders and heroes and wonderfully thin and attractive people. We use the term personality in day-to-day language, and we invoke a wide range of adjectives to characterize others and ourselves. In this sense, personality has become an implicit construct for the general public; it is not fully or specifically defined in that context, but it is commonly understood and accepted, nonetheless. However, when we use the term within the scientific field, personality should be seen as a theoretical construct, invoked to help us understand individual differences. From a more formal standpoint, theorists and researchers have defined personality as a pattern of behavior, affect (emotional experience), or cognition (thoughts) that is typical of the individual, evidencing some degree of stability over time and across situations. The references to behavior, affect, and cognition in the definition also speak to the breadth of personality psychology as it attempts to encompass diverse contributions from subdisciplines within psychology as well as influences from other fields. The Stability and Change of Personality Beyond the Text: Research Spotlight How do researchers determine if your personality is generally stable or variable across the lifespan? In a recent study conducted by Terracciano, McCrae, & Costa (2010), a new approach to answering this question was employed. Their findings suggest that the stability of personality appears to increase with age, though this association stops at approximately age 30. After reading about this study, discuss the relative advantages and disadvantages to the approach used to answer this question. Read the article at http://www.ncbi.nlm.nih.gov/ pmc/articles/PMC2839250/ Our intuitive notions suggest that personality is stable, and this would be in keeping with most theoretical models of personality and its operational definition. Moreover, several researchers have devoted a significant part of their careers to establishing that personality is stable (e.g., Block, 1971; Kogan & Block, 1991; McCrae & Costa, 1994; see also Bleidorn, Kandler, Riemann, Angleitner, & Spinath, 2012), and this is now widely accepted as a central component of most personality theories. Of course, personality can change, even dramatically, though typically there are some unusual events that lead to such change. For example, in one of the most famous cases in neuroscience, Phineas Gage, while working on a railroad, had a steel tamping rod shoot right through the frontal lobe of his brain. As a result, he apparently experienced a dramatic change in personality. Whereas he had previously been a quiet, hard-working, dependable employee, he became childish, obstinate, self-indulgent, and given to excessive profanity. In some cases, brain-injured individuals who had been severely aggressive became more docile; others, like Phineas Gage, who were initially gentle and pacific, became extremely violent after suffering brain trauma. Case studies have also shown that the long-term influence of alcohol or drugs can change personality, and progressing dementia, such as Alzheimer's, can result in personality changes, such as individuals becoming more paranoid and even aggressive. Personality, Temperament, Character, Traits and Factors, and Mood States Central to the notion of personality are the related, but theoretically distinct, constructs of temperament, character, traits and factors, and mood states. Temperament Temperament generally refers to an individual's basic biological predispositions, which are thought to be present at birth. For example, most parents can discern clear temperamental differences in their children, despite their genetic relatedness. Some infants appear to be "difficult," whereas others are seen as being "easy." Some are outgoing and tend to explore the world easily, whereas others are more shy and introverted. Dimensions of temperament are thought to reflect a strong genetic basis, largely because the infant has had relatively little time for the environment to be a major influence. Given that temperament is defined as one's natural tendency to behave outside of extended environmental influence, there has been some debate as to whether temperament is actually synonymous with personality—whether the two are in fact one and the same. Recently, the argument has been made that the two concepts are more alike than they are different (e.g., Caspi, Roberts, & Shiner, 2005; McCrae et al., 2000). Specifically, Caspi and colleagues cite a confluence of research suggesting that personality and temperament both (1) show moderate genetic influence, (2) are influenced by environmental factors, (3) focus on differences in the experience of positive and negative emotions for the most central traits, and (4) characterize traits that overlap with nonhuman species. In fact, the more interesting question no longer appears to be whether personality changes during the lifespan (the general consensus is that it changes very little), but, instead, the focus is on determining the points in one's life where change is most likely to occur (Caspi et al., 2005). Character Character is a commonly used term that generally refers to basic, enduring traits related to moral or ethical qualities. Character might be described in terms of characteristics such as integrity, honesty, morality, and stability. Character assessment judges how a person acts in various contexts. For example, what type of character would explain an apparently remorseless individual? Explanations based on character are most often seen in the psychodynamic literature to describe the inner workings of such people. The term character was used early in the literature, whereas personality is now much more common. Traits and Factors Traits are specific, stable features of personality such as persistence, integrity, and honesty. Using factor analysis, trait psychologists have done extensive studies to group related specific traits into broader factors that can account for variations in personality. For example, the traits kind, affectionate, and sympathetic have been grouped into the main factor agreeableness in the "big five" factors of personality (Costa, McCrae, & Dye, 1991). Thus, the primary distinction between traits and factors is the level of study, with traits at the lower level, reflecting more specific constructs. In contrast, factors reflect broad aggregates of related traits, and they provide an organizational framework for traits. Mood States Mood states refer to conditions that fluctuate over time and across situations. Recall that a trait is a stable and predictable personality characteristic that is consistent in various situations and over time. These distinctions are important for understanding personality. For example, George, who is depressed today, may withdraw and appear preoccupied and difficult to engage interpersonally. If we assess his personality at this time, his depressed state (or mood) might lead us to the inaccurate conclusion that he is introverted (trait). Later, when he is no longer depressed, George might become more outgoing and socially responsive. Thus, a personality trait may be profoundly influenced by an affective state, or mood state. Although we can make a conceptual distinction between a state and a trait, there is some ambiguity when considering the extent to which behavioral, affective, and cognitive patterns must be present before they are labeled as personality, as opposed to the more transient mood state (Lecci & Wirth, 2006). In fact, no clear definition of stability has been articulated, but clearly the longer a behavior, affect, or cognition lasts, the more likely it would be characterized as personality. One can also examine measures of personality relative to measures of mood to find some of the practical differences. For example, when assessing personality, researchers will often ask how people think, feel, and act "in general." Whereas when focusing on mood-type constructs, the assessment tools might ask how people are thinking, feeling, and acting at that particular moment. Culture While temperament, character, traits and factors, and mood states are all important constructs, culture is another component that must be considered in the study of personality. Most of the theories we will cover in this text emphasize to varying degrees the importance of early experiences in the development of personality, and many scholars believe that parenting styles are determined to a high degree by the dominant culture of the parents (Chang, 2007; Keshavarz & Baharudin, 2013). Part of the socialization (parenting) process is passing on cultural values (Corsaro & Elder, 1995). Emile Durkheim’s (1912) seminal work “The Elementary Forms of Religious Life” sheds some light on this process. Durkheim’s basic argument is that shared enacted social practice is the foundation of both cognition and morality, and that religious practice is the best illustration of this dynamic. While the predominant thinking of his day was pragmatism, for Durkheim, the dynamic relation was inherently socially based, and the critical action was social action (mostly in the form of enacted social practice), not individualized problem solving. Social practice (which included religious practice) was a way for people to meet their personal as well as their social needs, and had a fundamental impact on the individual life experiences of the members of the social group. He believed that socially enacted practices create the individual experiences. Thus, the personalities of a child raised in a devout Amish community, one raised in a Jewish home, one raised in a commune, and one raised by atheists in a high rise in Manhattan are bound to have differences based on their cultural environment. And those are just examples from American culture. Bronfenbrenner’s (1972) research demonstrated how the then powerful communist culture impacted the socialization of Russian children. It is interesting to note that after a few generations, the family, the state, the school and the peer group all participated in socializing the conformity necessary to maintain the communist system. Even perceptions of temperament are affected by culture. What is considered an easy or a difficult temperament in children depends on cultural values. Dworetszky and Davis (1989) cite a study of easy and difficult children done in 1984 among the Masai, a nomadic tribe of African warriors. They found that, because of the harsh environmental conditions, those children that Westerners would consider difficult were actually more highly valued by their parents and had much lower rates of childhood mortality. In this case, the “difficult” behaviors actually increased the child’s chances of surviving to adulthood, while the easy (more passive—less demanding) children received less attention and died with much greater frequency. More recently, Haase, Jome, Ferreira, Santos, Connacher, and Sendrowitz, (2014) found that culture influences individuals’ capacity for tolerating information overload. Even idioms and proverbs in different cultures may reflect variations in what characteristics of the individual are most valued. We are familiar with the saying “the squeaky wheel gets the grease,” which suggests that an extroverted individual who is self-focused in their approach may be more adaptable. However, the Japanese proverb “the nail that stands out gets hammered down” might suggest that a more introverted and group-focused mentality is preferable. But culture is a difficult construct to include in a concise theory because culture does not describe one way of being; it describes thousands of diverse and nuanced ways of being that can change or be changed. Nevertheless, it cannot be ignored when looking at the development of personality (see Chapters 6–9 for specific examples of cultural considerations as they apply to different theoretical perspectives). A second way that culture impacts our study of theories of personality is to look at who is doing the theorizing. For the most part, the predominant theories in personality development come from Western thinkers. The inclusion of other cultures is a relatively recent phenomenon. In fact, a meta-analysis done by Henrich, Heine, and Norenzayan (2010) noted that “behavioral scientists routinely publish broad claims about human psychology and behavior in the world’s top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich and Democratic (WEIRD) societies. Researchers—often implicitly—assume that there is little variation across human populations or that the “standard” subjects are as representative of the species as any other population” (p. 1). This does not negate the value of psychological studies and their resulting theories. It is, however, important to understand the lens through which those theories were conceived. Nature and Nurture One of the oldest debates about human nature concerns how much of our personality can be traced to biology and genetics (nature) and how much depends on our upbringing, environment, and culture (nurture). Research suggests that part of this answer depends on which aspect of personality is being studied. For example, when considering the trait of neuroticism, it appears that there is a relatively strong genetic component, with genetics accounting for upwards of 60% of the variability in neurotic behavior (e.g., Saudino & Plomin, 1996; see also Plomin, Haworth, Meaburn, Price, & Davis, 2013). In contrast, traits like creativity (also referred to as openness to new experience) appear to be influenced to a greater degree by one's environment. However, the trend has been to move away from the traditional contrast of nature versus nurture. In fact, the nature-nurture debate has more recently been referred to as a false duality (Traynor & Singleton, 2010), such that, with few exceptions, we have come to understand that both the environment of the individual and the individual him- or herself are significant contributors to the resulting action. Indeed, taking the above examples of neuroticism and creativity, it is still the case that the environment plays a substantial role in neuroticism, and genetics are still influential with creativity. Within the field of personality psychology, the nature-nurture distinction was captured by the "person-situation" debate, which examined how stable a person's personality is across varied contexts. Researchers initially vied for who could explain more variability in human behavior (e.g., Bem & Allen, 1974; Epstein & O'Brien, 1985; Mischel, 1968). However, more nuanced questions subsequently emerged, focusing instead on the circumstances under which either nature or nurture may have a greater influence on behavior. The latter includes defining complex interactions, such as how some traits are especially salient for certain individuals and therefore demonstrate greater cross-situational consistency compared to those same traits in others for whom the traits are less salient (e.g., Cheek, 1982; Zuckerman, Koestner, Deboy, Garcia, Maresca, & Sartoris, 1988). Currently, the person-situation debate adopts an integrative perspective with a focus on the interaction between the two (e.g., Donnellan, Lucas, & Fleeson, 2009; Webster, 2009). Epigenetics While the nature verse nurture question has been a staple of psychological debate and research for years, the emerging field of epigenetics is rendering that dichotomy obsolete. Sigmund Freud believed that “anatomy is destiny,” that our gender and our genes determine who we become. On the other extreme, the early behaviorists believed that the environment was king, that we are little more than the response to whatever stimuli we encounter. If you want a different response, just change the stimulus. However, we now know that the two are not distinct and mutually exclusive forces leaving their mark on our development, but that environment actually triggers or lays dormant the expression of our genes. Epigenetics is a revolutionary and burgeoning field of scientific study. Scientists have discovered that our environment creates chemicals that work on the genetic code of our DNA, and it is the process of our DNA sending a message to our RNA (known as transcription) that becomes the template for protein synthesis. This is where the action and the outcomes occur. In Epigenetics: How Environment Shapes our Genes, Frances describes the process like this. Rather than the gene being the controlling executive in this process, think of it more like the gene is a “member of an ensemble cast of biochemicals, the interaction of which constitutes a cell. The executive function resides at the cell level; it cannot be localized in its parts. Genes function as material resources for the cell. In this view, each stage of protein synthesis is guided at the cellular level. But most fundamentally, the ‘decisions’ as to which genes will engage in protein synthesis at any point in time is a function of the cell, not the genes themselves” (Francis, R.C., 2011, p. 19). And these cellular decisions are affected by our environment and in some cases, the environments of our ancestors (Simmons, 2008). So it is really the interplay between our nature (our genes) and our nurture (our environment), rather than each one’s impact on us, that is important. Twin studies have long been used to study heritability. Monozygotic twins (identical twins) share exactly the same DNA, yet they don’t always develop exactly the same way. Epigenetics provides the explanation as to why one twin might develop schizophrenia while the other does not, even though they both would have inherited the predisposition and most likely share similar environments, at least in infancy (Carey, N., 2012). We will explore more about emerging neurosciences like epigenetics in Chapter 4. How Related Disciplines Have Contributed to Personality Personality is not only the province of the behavioral sciences and personality theorists.