CHAPTER 10

EYSENCK'S BIOLOGICAL TYPOLOGY

Concepts and Principles

• Eysenck suggested integrating personality psychology and experimental psychology by:

– Identifying the main dimensions of personality

– Devising means of measuring them

– Linking them with experimental, quantitative procedures

Identifying and Measuring the Main Dimensions of Personality

• Eysenck ‘s definition of personality: more or less stable and enduring organization of a person’s character, temperament, intellect, and physique, which determines his unique adjustment to the environment

• Typology: means of classifying behavior through the use of continuous, highly abstract concepts (types) that encompass clusters of correlated traits

Identifying and Measuring the Main Dimensions of Personality (cont'd.)

• Explanation of behavioral differences on the basis of inhibitory cortical processes that hinder nervous system arousal

– Extraverts: individuals who have an outgoing and sociable approach to life

– Introverts: individuals who have a shy and retiring approach to life

– Neurotics: individuals who are emotionally unstable and overly reactive to stimuli

– Psychotics: individuals who are aloof, inhumane, aggressive, and insensitive to the needs of others, but also creative

Identifying and Measuring the Main Dimensions of Personality (cont'd.)

• Creative geniuses are individuals who are often psychotic

– Divergent thinking: geniuses and psychotics both have the ability to think along many different paths, to consider alternatives not ordinarily considered in trying to solve problems

– A lack of serotonin (chemical neurotransmitter in the brain) and an excess of dopamine (neurotransmitter in the brain) that, in excessive amounts, can reduce cognitive inhibitions

An Update on the Association Between Dopamine Levels and Creativity

• Convergent thinking: focuses on one idea from an array of ideas in arriving at a solution that society later sees as, not only original, but as socially useful

– Chermahini and Hommel (2010) found that lower levels of dopamine were associated with greater convergent thinking

• Divergent and convergent thinking are both necessary for creativity

– Provides originality and social usefulness

Inhibition Theory

• Inhibition theory: explanation of behavioral differences on the basis of inhibitory cortical processes that hinder nervous system arousal

– Extraverts: relatively strong inhibitory processes and weak excitatory processes

– Introverts: strong excitatory processes and weak inhibitory processes

– Neurotics: individuals who are emotionally unstable and overly reactive to stimuli

• Reactive inhibition: each time a person responds, a small increment of neural fatigue is built up

– Over many responses, fatigue builds to the point where the person stops responding

Arousal Theory

• Cortical arousal: state of the cortex during periods of perceptual or cognitive activity

• Arousal theory: explanation of behavioral differences in terms of the interactions between inherited levels of nervous system arousal and levels of environmental stimulation

Arousal Theory (cont'd.)

• Ascending reticular activating system (ARAS): part of the central nervous system located in the lower brain stem; it is involved in the arousal of the cerebral cortex

• Autonomic nervous system: part of the peripheral nervous system usually not under the individual's voluntary control that regulates the operation of internal organs and glands; it consists of sympathetic and parasympathetic subsystems

• Extraverts: brains have lower innate levels of arousal and are less responsive to stimulation

• Introverts: brains have higher innate levels of arousal and are more sensitive to stimulation

• Examples of research findings: introverts performed more poorly on a reading comprehension test while watching TV than extraverts; extraverts tend to consume more chocolate, coffee, tea, and soft drinks than do introverts

Arousal Theory (cont'd.)

• Autonomic activation and neuroticism

– Visceral brain: parts of the brain that underlie emotional feelings and expression; also known as the limbic system

– Neurotics have lower thresholds for activity in the visceral brain and greater responsivity of the sympathetic nervous system (division of the autonomic nervous system that mobilizes the body's resources for action); thus, neurotics overreact to even mild forms of stimulation

• Hormones and psychoticism

– Androgens: male sex hormones; in mammals, the principal one is testosterone

– Maleness linked to antigens (stimulate the production of antibodies); schizophrenics have antigens in their bodies

Personality Development

• People are born with certain innate predispositions to respond in particular ways to the environment

– These predispositions (or traits) can be altered to some extent by socialization demands

The Role of Heredity

• Eysenck found the strong genetic basis of the primary personality types confirmed in three ways:

– The same three personality orientations are found universally

– These traits show stability within given individuals over long periods of time

– The evidence provided by twin studies is consistent with the genetic hypothesis

• Monozygotic: twins who develop from the splitting of a single fertilized egg (also called identical twins)

• Dizygotic: twins that develop simultaneously from two separate fertilized eggs (also called fraternal twins)

The Role of Socialization

• Extraverts learn the rules of socialization less quickly and efficiently than introverts

– They tend to be less socialized than introverts

– They are more likely to show more antisocial behavior and become criminals than introverts

Intelligence, Heredity, and Social Policy

• Intelligence is a major personality factor; largely genetic, but can be shaped by learning environment

• Direct physiological measures of biologically based intelligence may provide a less culturally-biased approach to measuring intelligence

– Electroencephalogram (EEG): recording of electrical activity in the cerebral cortex obtained by means of electrodes placed on the skull

– Evoked potentials: patterns of waves that occur in the brain following its stimulation

Assessment Techniques

• Relied on host of experimental techniques to study personality

– Eyeblink conditioning: classical conditioning paradigm in which a tone is used as the conditioned stimulus, and a puff of air to the eye is the unconditioned stimulus

• Conditioning occurs when the conditioned stimulus alone is sufficient to produce the eyeblink response

– Electrodermal response: changes in the electrical conductance of the skin that are associated with arousal

– Pupillary response: changes in dilation of the pupils of the eyes associated with arousal

– Research on lower animals

Theory's Implications for Therapy

• Behavior therapy: multifaceted approach to the treatment of disorders based on the principles of learning

– Counterconditioning: procedure often utilized for therapeutic purposes, in which a conditioned response (CR) is weakened by associating the stimulus (CS) that evokes it with a new response that is antagonistic (incompatible) with the CR

– Modeling: demonstration of behavior by one person so that another person can imitate it

– Flooding: client is exposed to the most intense stimuli that evoke fear, typically for prolonged periods of time, in an effort to extinguish it

– Systematic desensitization: reduces the strong anxieties associated with various stimuli; the client is gradually exposed to them and, at each level in the anxiety hierarchy, learns new responses through counterconditioning

Evaluative Comments

• Comprehensiveness: broad in scope

• Precision and testability: generally precise and testable

• Parsimony: fails to meet the parsimony criterion; too simplistic

• Empirical validity: much empirical support for Eysenck's arousal theory, especially in regard to the behavior of extraverts and introverts; much more work needs to be done for the neurotic and psychotic types

• Heuristic value: theory is proving to be very stimulating to researchers, not only in Great Britain, but in other countries as well

• Applied value: considerable influence on researchers in cognitive behavior therapy