Unlike laypeople, psychologists believe people can measure personality using reliable scientific tools. Indeed, the whole field of psychometrics is dedicated to measuring differences between people in various psychological concepts, including personality. Personality assessment combines a variety of theories and methods, including common sense, probability theory and statistical testing. Life record data (L-data) deals with a person’s life history or biographical information. The main task of personality psychologists is to demonstrate that the assessment methods they use are, in fact, measuring specific personality traits, and that they are accurately doing so. In recent years, there has been an increased interest in alternative methods for objectively assessing personality. One compelling example is the Implicit Association Test (IAT). An aim of psychophysiological measurement is to elucidate the biological processes underlying factor-analytically derived dimensions of personality. There are several scientific investigations of the reliability and validity of astrology as a tool to assess personality.

This chapter presents the most salient psychological theories of personality. Personality is a core determinant of individual differences in everyday behaviors. The chapter discusses the difference between what psychologists broadly refer to as normal and what they regard as abnormal or clinical/mental illness. If one looks for an Elvis among personality psychologists, Sigmund Freud would be the one. During the mid-20th century, behaviorism emerged as a dominant paradigm for understanding human behavior, including personality. Although the social cognitive theory of personality has its origins in the radical behaviorist tradition, it emerged in clear opposition to it. According to the lexical hypothesis, historically, the most important and socially relevant behaviors that people display will eventually become encoded into language. Indeed, personality disorders are defined as long-standing, pervasive, and inflexible patterns of behavior and inner experience that deviate from the expectations of a person’s culture.

This chapter discusses the implications of using personality inventories in the context of identifying bad or problematic traits, such as narcissism, machiavellianism, and psychopathy. Evolutionary theory states that behaviors, traits, and genetic materials survive only if they are adaptive to the environment the organism finds itself in. As evidence has revealed, conduct disorder in children is a good marker for predicting psychopathy and antisocial outcomes in later years. Although personality tests are rarely used for the purpose of educational selection, scores on these tests correlate with several educational performance outcomes. The chapter examines current trends in online personality profiling in the context of consumer behavior. The market for online dating is huge and growing and an increasing number of single individuals subscribe to these services in order to find their ideal partners. Faking is an important criticism as many organizations will ask new applicants to undergo a personality assessment.

This chapter suggests some new directions that personality research is, or should be, taking as well as the future agenda of this research. In contrast, personality psychology provides us with a solid evidence base that people can lean on when searching for answers about human nature. Personality refers to the stable and consistent patterns we observe in how people behave, feel, and think. Associations between personality and intelligence have been found on the measurement level and hypothesized at a conceptual level. It is supposedly human nature not to trust humankind to provide the unselfish responses in questionnaires, or to possess an adequate level of self-awareness. Admittedly, this trend has been changing. An increasing number of organizations are using self-report personality measures and even laypeople seem to accept the notion of questionnaires more kindly than before.

This chapter reviews the literature that shows how, and the extent to which, personality impacts our personal lives. Indeed, research indicates that healthy romantic relationships play a key role in fostering emotional well-being and physical health. Typically, psychologists have viewed nonphysical factors in interpersonal attraction as trivial in understanding initial attraction. It seems likely that the observer’s personality should influence interpersonal attraction. The chapter discusses the possibility of our personality affecting an arguably less obvious outcome, namely, our health. Several meta-analyses have also shown Neuroticism to be negatively related to health outcomes. Specifically, high neuroticism combined with high conscientiousness may lead to protective behaviors. The preferred term in psychology to refer to happiness is subjective well-being. It seems that factors such as health, income, educational background, and marital status account for only a small amount of the variance in well-being measures.

This chapter describes the main causal theories of personality, which deal with the question of why, that is, why people differ in various ways. It addresses the question of personality change and development, that is, whether people can change, and if so, the extent to which they actually do. The chapter also discusses the main factors that contribute to change. To tackle the question of why personality differences between people exist, psychologists have generally occupied three different fields of investigation: the genetic, the biochemical, and the evolutionary. Behavioral genetics is an area of psychology concerned with the assessment of the relative contribution of genetic and nongenetic influences on various individual variables of difference, including personality, intelligence, and psychological disorders. Behavioral geneticists distinguish between two types of environment: shared environment and nonshared environment. The structure of temperaments seems to differ from the adult personality structure.