Personality is a term that has many general meanings. Sometimes the word refers to the ability to get along well socially. For example, we speak of experiences or relationships which are said to give a person "more personality." The term also may refer to the most striking impression that an individual makes on other people. We may say, "She has a shy personality." 

To a psychologist, personality is an area of study that deals with complex human behaviour, including emotions, actions, and cognitive (thought) processes. Psychologists study the patterns of behaviour that make individuals different from one another. 

The nature of personality 

Personality types. For hundreds of years, people have tried to group the vast differences among human beings into simple units. Some of the resulting groupings divide people into personality types based on certain characteristics. 

The ancient Greek doctor Hippocrates divided individuals into such types as sanguine (cheerful) and melancholic (depressed). He attributed their behavioural differences to a predominance of one of the body fluids. For example, Hippocrates believed that a person was cheerful if blood (sanguis) was the dominant influence on his or her behaviour. 

Some of the more recent theories about personality types have tried to associate body build and temperament. Classifications based on body measurements were developed by two psychiatrists, Ernst Kretschmer of Germany and William Sheldon of the United States. 

The Swiss psychologist Carl Jung, who studied psychological characteristics, classified people as introverts or extroverts. 

The simplicity of personality-type theories is appealing, but it also limits their value. An individual's behaviour is so complex, diverse, and variable that the person cannot be sorted usefully into a simple category. 

Personality traits. 

Related to personality-type theories is the search for broad traits or dispositions to describe enduring differences among people. One of the early workers in this field was the British psychologist William McDougall. Personality traits are regarded as dimensions that range from high to low. For example, anxiety is a trait that varies from the greatest anxiety to the least anxiety. Most people have some degree of anxiety along the scale between the two extremes. Psychologists have studied such personal attributes as aggressiveness, dependency, and extroversion-introversion. 

Studies of personality traits help reveal the relationships between an individual's different personal attributes. For example, a group of children may be tested for intelligence and may also be given questionnaires about their attitudes. In addition, they may be asked to rate their own characteristics, and may be rated by their teachers. The results are then correlated statistically to discover the relationships among all this information. 

Ratings and self-reports. 

Research on personality traits tends to rely heavily on broad ratings of personality. In self-ratings, a person indicates the degree to which he or she thinks he or she possesses certain personality characteristics. Ratings may also be obtained from teachers, or others who know the person or who have watched the person in special situations. 

These judgments may be affected by many types of bias. A person may give the responses that he or she thinks are expected and socially desirable, even if they are not true. Moreover, the answers may reflect preconceptions and stereotypes (fixed ways of thinking), rather than an accurate description of behaviour. Tests that ask a person to rate such attributes as friendliness or adjustment provide broad self-characterizations rather than detailed descriptions of behaviour. Consequently, the findings of such tests may partly reveal the concepts and stereotypes that people apply to themselves and to others. These findings may not necessarily reflect the people's actual behaviour outside the test. 

Some techniques are designed to reduce the role of personal meanings and concepts. Other approaches deliberately seek to clarify the individual's concepts about himself or herself. These personal concepts are especially important in theories that stress the role of the self and one's image of oneself. For example, in his theory of self-realization, the American psychologist Carl R. Rogers focuses on phenomenology--a person's private experiences and perceptions. 

Projective tests. 

Some investigators have tried to avoid the problems of relying on a person's ratings or reports about himself or herself by creating indirect clinical techniques in the form of projective tests. These methods require the person to respond to a situation in which there are no clear guidelines and no right or wrong answers. The person may be asked how inkblots appear to him or her on the Rorschach Test. Or the person may be instructed to create a story about the characters in a series of pictures in the Thematic Apperception Test. Projective techniques rely on a trained clinician to interpret the person's attributes indirectly from test behaviour. The value of this approach for revealing aspects of personality is controversial and is still being studied. 

Freud's psychoanalytic theory. 

According to the Austrian physician Sigmund Freud, the personality has three parts: (1) the id, which represents instinctive impulses of sex and aggression; (2) the ego, which represents the demands of the real world; and (3) the super-ego, or conscience, which represents standards of behaviour incorporated into the personality during childhood. 

According to Freud, mental life is characterized by internal conflicts that are largely unconscious. Impulses from the id seek immediate gratification, but they conflict with the ego and the superego. When unacceptable impulses threaten to emerge, a person experiences anxiety. To reduce this anxiety, the person may use various personality defences. The person may, for example, displace (transfer) his or her emotions to less threatening objects. A child who is afraid to express aggression toward his or her father may become angry at his or her pet dog instead. 

Freud's ideas have had great influence on the study of personality, but they are highly controversial. Many of his ideas had to be modified severely by psychologists to take greater account of social and environmental variables. 

Personality and environment 

Trait theories and psychoanalytic theories both assume that broad internal personality dispositions determine behaviour in many situations. However, research on the consistency of various personality traits indicates that what people do, think, and feel may depend greatly on the specific conditions in which their behaviour occurs. 

People may be honest in one situation and dishonest in another. They may be passive in some situations but aggressive in other situations or with different people. Many contemporary approaches to the study of personality therefore emphasize the role of specific social experiences and environmental events in the development and modification of behaviour. Psychologists are gradually moving away from broad theorizing about the nature of personality. Instead, they are studying the conditions that determine complex behaviour. 

Personality development. 

Some psychologists have examined the effects of early experiences on later personality development. Other investigators have studied the stability of particular patterns of personality over long periods of time. Their findings suggest that such tendencies as striving to achieve may persist to some degree from childhood into adulthood. However, research has also shown that personality continues to change as a result of new experiences and modifications in the environment. 

Throughout their development, people learn about themselves and their world by observing other people and events. They also learn by trying new kinds of behaviour directly. The rewards and punishments they receive after trying various patterns of behaviour affect their future behaviour in similar situations. People also learn by observing the results of the behaviour of such social models as their parents. Suppose children repeatedly see adults succeed in antisocial or criminal acts. If they see such behaviour rewarded, they are more likely to copy it than if it is punished. Children more readily imitate models who are powerful or who reward or take care of them. 

As children develop, they copy some of the behaviour of many models, including their friends as well as their parents. They combine aspects of their behaviour into new patterns. Through direct and observational learning and cognitive growth, they also acquire standards and values that help them regulate and evaluate their own behaviour. Gradually, people develop an enormous set of potential behaviours. The particular behaviour patterns they show in specific situations depend on motivational factors.

People's cognitive and social learning experiences vary as a result of the particular social and cultural conditions to which they are exposed in the home, at school, and in other environments. Personality traits may predict many important aspects of behaviour. But the setting in which behaviour occurs often provides the best predictions about what people will do. Thus, although extensive differences among people are found in most human actions, considerable uniformity and regularity can occur when environmental conditions are very powerful. Strong success experiences in a new situation, for example, may override the effects of past failure experiences and of personality traits in determining future reactions to that new situation. Similarly, prolonged or intense environmental changes, such as lengthy hospitalization or imprisonment, may lead to major personality changes. A person who has severe difficulties in personal relationships is said to be suffering from a personality disorder. 

Emotional reactions. During the course of development, we acquire intense emotional reactions to many stimuli. Events that once were neutral may become either pleasurable or painful as the result of conditioning 

Some reactions may involve strong anxiety and can have crippling effects. For example, children who have frightening experiences with dogs may become afraid of all dogs. This fear may generalize (spread) even more widely to other animals and to such objects as fur coats, or hair. Such fears are especially hard to unlearn because these people tend to avoid all contact with situations that provoke fear. Consequently, these people prevent themselves from having experiences that might eliminate their fear--petting harmless dogs, for example. Emotional upsets of this kind may also be acquired by observing the fear reactions of other people. 

As a result of social learning, we generalize from our experiences to new but similar or related situations. But we do not generalize indiscriminately. A young boy may learn to express physical aggression in many settings, including school, play, and home. But he also learns not to be aggressive in other situations, such as when visiting his grandparents. 

Personality change. 

Research on cognitive and social learning processes is leading to new forms of psychotherapy to help people who have psychological problems. Some of these problems are the result of learning deficits. For example, some people lack fundamental academic and vocational skills, such as reading proficiency. Individuals who have inadequate relations with others need to learn essential interpersonal skills. Some people have these basic skills, but they suffer because of emotional fears and inhibitions. 

Psychotherapy aimed at changing personality tends to stress insight into the history through which the problems developed. Learning methods try to change the disturbing behaviour itself by carefully planned relearning and conditioning techniques. Still other forms of personality change may be achieved by creating special environments for learning more adaptive personality patterns. 

Additional resources 

Carver, Charles S. and Scheier. Perspectives on Personality. Ed 3. Allyn and Bacon, Needham Heights, Massachusetts, U.S.A., 1995. 

Cook, Mark. Levels of Personality. Holt, Rinehart and Winston, London, 1984. 

Funder, David C. The Personality Puzzle. W.W. Norton, New York, U.S.A., 1996. 

Damon, William. Social and Personality Development: Infancy Through Adolescence. Norton, New York, 1983.