Social psychology and personality psychology have the same job: to seek to understand the meaningful, consequential, and for the most part social behaviors of daily life. Cognitive psychology examines component processes such as memory, perception, and cognition. Biological psychology seeks to understand the physical underpinnings of behavior in the anatomy, physiology, functional organization, genetic basis and evolutionary history of the nervous system. Developmental psychology explores the roots of behavior in genetics and early childhood experience, and changes across the life course. All of these fields could be viewed as foundational for the common concern of social and personality psychology, which is to understand what people do every day. In this light, it is unsurprising that courses in social and personality psychology are among the most popular offerings on most college campuses; their subject matter is not only important, it is personally relevant and intrinsically interesting.
This division of labor makes a certain amount of sense, but problems arose as the fields gradually became so specialized that many practitioners of each field became unaware of the basic principles, findings and methods of the other, and grew worse when social psychologists began to suspect that personality psychology’s emphasis on individual differences was misguided. In his memoirs, the eminent social psychologist Roger Brown described one memorably awkward encounter between the two traditions:
Personality can be defined as an individual’s characteristic patterns of thought, emotion, and behavior, together with the psychological mechanisms – hidden or not – behind those patterns (Funder, 2007). The ultimate goal of personality psychology is to explain every individual from the inside out. The mission includes describing, measuring and explaining how people differ from one another, uncovering the conscious and unconscious thoughts and feelings that drive behavior, and predicting what people will do in the future, among other goals. But this mission has one problem: it is impossible. The complete study of the individual encompasses too many considerations at once to be feasibly pursued by investigators with human limitations of time and intelligence.
The Basic Approaches to Studying Personality
The biological approach to studying personality searches for the organic roots of individual differences using anatomy, physiology, genetics, and evolutionary theory.
Anatomy. Research focusing on anatomy attempts to identify brain structures that play a role in various personality traits. For example, research using functional magnetic resonance imaging (fMRI) has shown that shy people, compared to people described as more “bold,” respond to pictures of unfamiliar people with bilateral activation of the amygdala, and to pictures of familiar people with activation on just the left side of this organ (Beaton, Schmidt, Schulkin, Antony, Swinson & Hall, 2008). The challenge for the next generation of research will be to use these intriguing findings to illuminate aspects of personality that were not previously apparent, and to outline psychological processes and interactions among them that are not detectable from overt behavioral data alone. Modern imaging technology offers a theoretical promissory note that will someday be paid but, to date, remains to be cashed.
Physiology. Biological research on personality also addresses physiology, examining biochemicals (neurotransmitters and hormones) that might be associated with individual differences in behavior. Dopamine and serotonin are widely studied neurotransmitters. Research suggests that dopamine is involved in the experience of reward and the reinforcement of behavior (Blum et al., 1996), while serotonin plays a role in emotional regulation and feelings of well-being (Knutson et al., 1998). The hormone testosterone has received considerable attention and appears to play an important role in sexual behavior and aggression (Zuckerman, 1991; Dabbs & Morris, 1990, respectively). Cortisol, the well-known “fight or flight” hormone associated with anxiety, fear and aggressive response, appears to be surprisingly low in shy individuals (Beaton, Schmidt, Ashbaugh, Santesso, Antony, McCabe, Segalowtiz & Schulkin, 2006). But it also is low in people high on the trait of sensation-seeking, so the situation, as always, is complicated (Zuckerman, 1998).
Behavioral Genetics. Behavioral genetics and evolutionary psychology both focus on the inheritance of individual differences in behavior. For the good and the bad, we are more similar to people with whom we share more genes (e.g., our parents) than fewer genes (e.g., our cousins). We look like our parents, we are more likely to have high blood pressure if our parents do, and we even have an IQ level similar to our parents. Behavioral genetics extends this knowledge and studies the question: Are those who are more genetically similar (e.g., monozygotic twins) more similar in personality compared to those who are less genetically similar (e.g., dyzygotic twins)? Decades of research has established that most and perhaps all personality traits are heritable to some degree. Indeed, one authoritative researcher seriously suggested that “the first law of behavioral genetics” should be everything is heritable (Turkheimer, 1998, p. 789). Genes matter, to at least some degree, to any psychological outcome and certainly any personality trait.
Evolutionary Psychology. Evolutionary psychology studies behavioral patterns proposed to have been adaptive during the development of the human species. It assumes that behaviors that are common to humans (a) have a genetic basis and (b) increased the likelihood of survival and/or reproduction during evolutionary history. The more a behavior helps an individual to survive and reproduce, the more likely the behavior is to be genetically transmitted, and therefore, appear in subsequent generations. Evolutionary psychology has particularly focused on variation in sexual behavior between males and females. It is commonly hypothesized that gender differences in behavior that are still present today exist because, in the history of evolution, the behaviors that increased the likelihood of reproduction for males were different from the behaviors that increased the likelihood of reproduction for females.
While biological research seeks to identify the specific physical foundations of behavior and personality, the psychoanalytic approach often operates on a level of almost metaphysical abstraction – one that, nonetheless, leads to unique insights and, on occasion, testable hypotheses. Psychoanalysis seeks to understand personality at the deepest psychological level and takes on the unique challenge of explaining what is going on in the hidden and sometimes dark recesses of the human mind. From a psychoanalytic perspective, personality is shaped by early childhood experiences and behavior is ultimately determined by the outcomes of unconscious processes and conflict. The psychoanalytic approach focuses on constructs such as the unconscious mind, defense mechanisms, attachment, and ego-strength.
The humanistic approach was originally based on an even less scientific tradition than psychoanalysis. Early pioneers, such as Carl Rogers (1951) and Abraham Maslow (1987), believed that personality is a special entity that cannot be studied dispassionately from a distance. They argued that unlike rocks and trees, people can perceive, think, and feel, and this fact makes the study of people fundamentally different from other sciences and more difficult than is usually acknowledged. The humanistic approach proposes that the key to understanding behavior requires appreciating each individual from his or her own unique perspective. Humanism is also different from the other approaches in that it focuses on human strength, growth, and well-being, rather than human weakness.
Humanistic psychology’s core concern with how people construct their views of reality is echoed in cross-cultural research, which involves understanding the ways in which people from different cultures may have fundamentally different views of the world.
Classic behaviorists ignore concepts like happiness and construals of reality because their approach strictly dictates that they study only that which can be directly observed. Behaviorism is a learning-based approach to studying personality and it places heavy emphasis on overt behavior and the rewards and punishments in the environment that condition individuals to behave in certain ways. From this perspective, personality is simply the behaviors that an individual performs as a result of environmentally imposed reinforcement contingencies.
The cognitive approach, which evolved from and overlaps with the social learning theories, focuses on perceptual processes, thoughts and beliefs, and motivational processes that form the basis of personality and behavior. One way of conceptualizing personality traits is to think of them as dimensions along which people think and perceive information differently. For example, one person might have the disposition to have positive thoughts more readily accessible, whereas another person might have the disposition to have negative thoughts more accessible.
The trait approach to studying personality places individual difference constructs (i.e., personality traits) front and center. According to Allport (1931), traits are psychological mechanisms that determine people’s responses to stimuli. He believed that traits motivate and organize an individual’s behavior and knowing an individual’s traits requires observing his or her behavior repeatedly. Such observation will reveal the consistent behavioral patterns from which the underlying psychological mechanisms can be inferred.
From this perspective, traits are like gravity. Gravity is a concept that describes the force of attraction between objects and explains a wide range of astronomical observations (e.g., how planets orbit the sun). Similarly, traits are psychological concepts that are used to describe individual differences in behavior and give coherence to a wide range of psychological observations. Nobody has ever seen either gravity or narcissism directly, but perhaps their nature can be discerned from their effects.
Behavioral Assessment of Personality
The foundation of empirical personality psychology is the observation of behavior – the only way to examine a personality construct is to propose a behavioral manifestation and then observe it. This is true regardless of the nature of the construct, which, as we have seen, might be anything from stimulus generalization, to rejection-sensitivity, to self-esteem, to conscientiousness, to gender identity. The scientific study of personality rests on the following simple formula: P → B. A researcher might theoretically view P as causing B, or view P as a summary of B, but the method of study remains the same.
When a researcher develops a personality test that measures a single trait, the trait is usually one that that seems particularly important and a huge effort may be made to explore all possible implications. The traits that receive this kind of attention vary over the years, for reasons that may be less than clear. Some traits appear to become well-known and widely researched because they address a social issue that seems particularly important at the time.
Other widely-used personality tests measure a large number of traits at once. The “many-trait” inventories are typically used to examine the many possible psychological characteristics that are related to an important behavior or life outcome. For example, the California Adult Q-set (CAQ: Block, 1978, 2007; Bem & Funder, 1978) consists of one hundred descriptions of specific psychological attributes (e.g., Is critical, skeptical, not easily impressed; Is a genuinely dependable and responsible person).
Finally, some personality research is motivated by the question: Which personality traits are the most important? Currently, the most widely accepted answer to this question is the Big Five. The Big Five represent the culmination of more than a hundred years of research aimed at reducing the many possible personality traits to an essential few (Galton, 1884; Thurstone, 1934; Allport & Odbert, 1936; Cattell, 1943; Fiske, 1949; Tupes & Christal, 1961; Norman, 1967; McCrae & Costa, 1987; Goldberg, 1990; Digman, 1990). Research on the Big Five traits is based, in part, on the lexical hypothesis (e.g. Goldberg, 1981), which proposes that anything truly important to human life will be labeled with words. This idea suggests that the most important personality traits will be encoded in language. Therefore, researchers extracted trait-adjective words from the Oxford Dictionary and factor analyzed ratings of them, many times over, along with scores on a multitude of personality inventories.
Although self-report questionnaires have traditionally dominated the literature and probably deserve credit for having contributed most of what has been learned about personality, they entail two major disadvantages. First, people may sometimes be unwilling to reveal undesirable aspects of their personalities. Second, people are not always aware of every aspect of themselves. Several studies suggest that people rate themselves higher on socially desirable characteristics (e.g., trustworthiness) and rate themselves lower on undesirable characteristics (e.g., laziness).
Person Perception and Accuracy
The way that an individual is perceived by others is highly consequential. Reputation determines the opportunities that others will make available to the individual and the expectations they will hold. A person with a good reputation will be trusted and find that other people like him or her; a person with a bad reputation probably not get the job that he or she wants, not attract his or her love interest, and be generally disliked. Moreover, a people tend to live up or down to their good or bad reputations because they tend to behave in ways that confirm the expectations of others (Rosenthal & Rubin, 1978; Snyder & Swann, 1978). The study of how people perceive one another is a major research topic in social and personality psychology (Macrae, this volume). It is called “person perception research” within social psychology and “accuracy research” within personality psychology and the difference in labels is more than superficial. The two research paradigms are based on fundamentally different philosophical perspectives, focus on different aspects of social perception, and are studied using different methodologies.
Person perception research in social psychology is based on social constructivism, in the sense that it treats the views people have of one another as mental constructions, a property of the social perceiver rather than of the person who is described. Therefore, the focus of person perception research is on the cognitive processes that underlie the construction of impressions.
Accuracy research within personality psychology follows a fundamentally different strategy. It is based on critical realism (Rorer, 1990), a philosophical approach which asserts that the best way to assess a judgment is in terms of multiple fallible external criteria that probabilistically indicate the degree to which it is a true reflection of reality.
Methods of Accuracy Research. The primary methodology involves comparing multiple sources of information about a person in order to evaluate the degree to which a personality judgment is accurate. For example, if Person A is judged to be high in extraversion by his or her acquaintance, we can evaluate this judgment by comparing it to Person A’s self-judgment of the degree to which he or she is extraverted, to direct observations of Person A’s behavior (e.g., does Person A talk more than others?), and to relevant life outcomes (e.g., does Person A successfully engage in an occupation that requires being outgoing and energetic?). Accuracy research differs from person perception research in that the typical study uses real people as the target of judgment and gathers personality judgments from people who know them in real life along with other indicators such as self-judgments, behavioral observations and life outcomes.
Although the accuracy and person perception paradigms differ in many ways, they are potentially complementary. It is not difficult to imagine an interdisciplinary effort that combined social cognition and accuracy research into one big theory that ultimately explained how people perceive one another. However, deep philosophical and methodological differences between social and personality psychology have stood in the way of this integration.
Towards a Cooperative Social-Personality Psychology
The most useful way to consider situational and personal variables is as interactional partners. This view was operationalized in Lewin’s (1936) well-known formula: B = f (P,S), which explicitly defines behavior as a function of the person and the situation. This equation implies that if we knew all of the relevant psychological properties of a person and all of the relevant properties of his or her situation, we could predict with high precision what the person would do.