G

GAEA/GAIA HYPOTHESIS. See LIFE, THEORIES OF.

GAIN-LOSS THEORY. See EXCHANGE/ SOCIAL EXCHANGE THEORY; INTERPERSONAL ATTRACTION THEORIES.

GALEN'S DOCTRINE OF THE FOUR TEMPERAMENTS. The ancient Greek physician/philosopher Claudius Galen (c. 130200) formulated the doctrine of the four temperaments of personality based on the earlier doctrine of bodily humors as outlined by the Greek philosopher Empedocles (c. 495-435 B.C.) and the Greek physician Hippocrates (c. 460-377 B.C.). Empedocles posited that the universe is made up of the four basic elements of: earth, fire, air, and water, where combinations of these four elements, in one way or another, can explain all know substances. Each of the four elements has corresponding "qualities": earth - cold and dry; fire - warm and dry; air - warm and moist; and water -cold and moist. When the qualities are taken with respect to the human body, they assume the form of four substances or humors: blood, yellow bile, black bile, and phlegm. Hippocrates considered these humors to be the basic constituents of the body where - depending on their deficiency, excess, or balance - they could cause both disease and health. In this sense, Hippocrates' naturalistic approach and explanations of cause-effect relationships anticipated modern medicine and psychology, rather than appealing to the presence of "evil spirits" as the cause of diseases. Later, Galen systematized the relationship of the Empedo-clean/ Hippocratic notions of elements/humors into a general personality theory of temperaments where an excess of blood characterized the sanguine (warmhearted, cheerful) person, a preponderance of black bile related to the melancholic (sad, fearful) personality, an excess of yellow bile led to the choleric (fiery, highly reactive) person, and an excess of phlegm typified the phlegmatic (slow, slug gish) individual. Galen's doctrine of the four humors and their corresponding temperaments was viable until about A.D. 1400, when the Renaissance and the rebirth of medicine took place, and the doctrine faded. Although Galen's doctrine now is chiefly of historical interest only, certain vestiges of terminology remain in our language, such as the expressions "bad humor," "good humor," and "humorless." Galen was one of the first investigators to speculate that the front part of the brain receives sensory impressions and the back part has motor functions, in the anticipation or initiation of brain-localization theories. Galen's doctrine of the temperaments served, also, as the intellectual basis for certain contemporary theories of personality that formulated and advanced the concept of types, such as W. Sheldon's triad of personality types: visceratonic - outgoing, cheerful, happy; somatotonic - athletic, energetic, vigorous; and cerebrotonic - inward, bookish, shy. In another case, A. Adler related his hypothesized four styles of life to Galen's four temperaments. The work of Hippocrates and Galen may have inspired some modern investigators to look for biochemical sources of variations in human personality and behavior, and the four temperament types themselves, detached from the humoral doctrine, have continued to interest prominent psychologists such as W. Wundt, I. Pavlov, and H. Eysenck. See also ADLER'S THEORY OF PERSONALITY; EMOTIONS, THEORIES AND LAWS OF; EYSENCK'S THEORY OF PERSONALITY; KRETSCHMER'S THEORY OF PERSONALITY; LEARNING THEORIES AND LAWS; PERSONALITY THEORIES; SHELDON'S TYPE THEORY. REFERENCES

Germany: Niemeyer. Kretschmer, E. (1922). Physique and character: An investigation of the nature of constitution and of the theory of temperament. London: Paul, Trench, Trubner.

Adler, A. (1927). The practice and theory of individual psychology. New York: Harcourt, Brace, & World. Sheldon, W., & Stevens, S. S. (1942). Varieties of human temperament: A psy-

chology of constitutional differences. New York: Harper. Galen, C. (1956). On anatomical procedures. London: Oxford University Press.

GALTON'S LAWS. The English natural scientist/psychologist Sir Francis Galton (1822-1911) has been called the "father of differential psychology" and was one of the foremost progenitors of the field of psycho-metrics (i.e., the quantitative measurement of psychological characteristics through psychological tests and statistical techniques). Gal-ton's contributions to differential psychology (i.e., the branch of psychology that studies the differences and variations in certain fundamental characters as manifested in different races and social groups, or in individuals of the same group) reflected his conviction that all human characteristics, both physical and mental, could ultimately be described in quantitative terms (cf., doctrine of eugenics - a term coined by Galton, refers to the notion that human qualities, such as character and intelligence, are inherited and that society should take deliberate steps to produce "good," "fine," or "superior" offspring; positive eugenics is the reproduction of desirable types, whereas negative eugenics is the attempt to prevent undesirable persons from reproducing offspring; the rise of racism, and the doctrines and goals of Nazism in particular in the 1930s and 1940s, caused eugenics to fall out of vogue). Galton's long-term concern and study of heredity led him to anticipate the polygenic theory of inheritance of continuous characteristics that was later developed by the English geneticist/statistician Sir Ronald Fisher (1890-1962). Galton anticipated, also, the formalized motor theory of thought via his finding that many scientists seemed to have no visual imagery at all (Galton, himself, apparently had clear visual imagery). In attempting to explain how his "men of science" could have ideas without visual images, Galton asserted that the missing faculty was replaced by other modes of conception, chiefly that of the "incipient motor sense," not only of the eyeballs but of the muscles generally (cf., synethesia effect - an experience of imagery where stimulation of one sensory modality, such as auditory words/sounds, arouses sensa tions in another sensory system, such as visual colors; thus, musical notes may arouse certain colors in the listener, or numbers may be experienced as sounds in the viewer). Galton was the first scientist to formulate clearly the so-called nature-versus-nurture question, that is, the relative contributions of heredity and environment to individual and group differences in human abilities, traits, and talents. He was the first, also, to note the methodological importance of monozygotic and dizygotic twins for estimating the relative effects of genetic and environmental factors in human variation (cf., epigenetic theory and its reference to changes in an organism that are due to environmental factors or to gene-environment interaction rather than purely to genetic factors). Galton investigated the inheritance of general ability by studying nearly 1,000 men who had achieved eminence, and recorded the frequency of eminent men among all their relatives (cf., Roeckelein, 1996). He found that as the degree of genetic kinship decreased, the percentage of eminent relatives also decreased in a markedly stepwise fashion - as predicted from Galton's model of genetic inheritance, which also explained in hereditary terms physical traits such as fingerprints and stature. From these data, Galton argued that mental ability is inherited in the same way as are many physical traits. For example, Gal-ton's law of filial regression to mediocrity is demonstrated in the trait of stature: the offspring of a deviant parent (i.e., a parent who is either very tall or very short) are, on average, less deviant from the mean of the population than is the parent regarding the trait in question. Thus, the offspring of two very tall or two very short parents would be more nearly of average height than the parents themselves. A corollary to this law is Galton's law of reversion, which refers to the reappearance of a recessive genetic trait that had not been present in the phenotypes for one or more generations. Galton explained the phenomenon of regression in terms of his law of ancestral inheritance, by which the genetic contribution of each parent to an offspring is 1/4, of each grandparent is 1/16, of each great-grandparent is 1/64, and so on. Presumably, each further-removed ancestral generation comes closer to being a random sample of the general popula tion. Therefore, the offspring's total genetic inheritance for the trait studied, being the sum of this infinite series of decreasing fractions, comes closer to the population mean than does that of the parents. This explanation for regression, however, has been rejected totally by modern geneticists. The concept of regression developed by Galton served as the basis for the statistical correlation methods formulated by the English statistician Karl Pearson (1857-1936). Galton first studied statistically the relationship between the heights of fathers and their sons; Galton hired Pearson as a statistician to work with him and his father on a series of investigations involving the contributions of heredity to the development of human attributes. In addition to regression and correlation, Galton's contributions to statistics and psychometrics include formulations and developments of the bivariate scatter diagram, multiple correlation, standardized or scale-free scores, percentile ranks, the use of median and geometric mean as measures of central tendency, and rating scales. The possible causes of regression among parents and offspring (or any other kinship) may be classified into three categories: errors of measurement, genetic factors, and environmental factors. There is nothing in the phenomenon of regression per se that proves either genetic or environmental causes or some combination of these. However, the complex methods of quantitative genetics that partition the total population variance in a trait into its genetic and environmental components may give an estimate of how much observed regression is attributable to genetic factors, to the environment, and to measurement error. See also EMINENCE, THEORIES/MEASURES OF; HARDY-WEINBERG LAW; IMAGERY/ MENTAL IMAGERY, THEORIES OF; INTELLIGENCE, THEORIES AND LAWS OF; MENDEL'S LAWS AND PRINCIPLES; NATURE VERSUS NURTURE THEORIES. REFERENCES

Galton, F. (1869/1962). Hereditary genius: An inquiry into its laws and consequences. London: Collins. Galton, F. (1872). Statistical inquiries into the efficacy of prayer. The Fortnightly Review, 12, 125-135.

Galton, F. (1874). English men of science: Their nature and nurture. London: Macmillan.

Galton, F. (1879-1880). Psychometric experiments. Brain, 2, 149-162. Galton, F. (1883). Inquiries into human faculty and its development. London: Macmillan.

Galton, F. (1889/1973). Natural inheritance.

New York: AMS Press. Hartung, J. (1985). Matrilineal inheritance: New theory and analysis. The Behavior and Brain Sciences, 8, 661688.

Roeckelein, J. E. (1996). Contributions to the history of psychology: CIV. Eminence in psychology as measured by name counts and eponyms. Psychological Reports, 78, 243-253.

GAMBLER'S FALLACY. See PROBABILITY THEORY/LAWS.

GAME THEORY. See DECISION-MAKING THEORIES; INNER EYE THEORY OF LAUGHTER.

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