DOCUMENT RESUME CG 026 769 ED 390 013 Rickman, David L. AUTHOi Evolution, Convolution, Dissolution: The Rise of TITLE Individual Differences in Human Developmental Psychology. PUB DATE [95] NOTE 17p. Viewrc;nts (Opinion/Position Papers, Essays, etc.) PUB TYPE (120) MFOI/PC01 Plus Postage. EDRS PRICE Behavior Development; Biological Influenc6s; DESCRIPTORS *Developmental Psychology; Environmental Influences; Genetics; Heredity; *Individual Differences; *Intellectual History; Intelligence; *Nature Nurture Controversy; *Science History ABSTRACT Although it is difficult to ascertain precisely the time at which the study of individual differences became recognized as a specialty within the psychological sciences, there appears to be much agreement among historians that its development was fostered primarily within the United States during the late 19th century. This paper examines the beginnings of research and application concerning individual differences and their social context in which it proliferated. Within this context, the nature versus nurture controversy is introduced, and a discussion about its importance to the field of developmental psychology follows. Charles Darwin's research was not always fully understood by others and some of the resulting pseudoscientific philosophies are discussed. The Eugenics movement, Social Darwinism, and intelligence testing are examined, with emphasis on the latter. Late nineteenth and early twentieth century conceptions of human development are explored. Sex differences in intelligence, functionalism, and behaviorism are also discussed in historical context. Contains 10 references. (JBJ) *********************************************************************** Reproductions supplied by EDRS are the best that can be made from the original document. --*.,),4************************************************************* CG Individual Differences 1 Evolution, Convolution, Dissolution: The Rise of Individual Differences in Human Developmental Psychology David L. Rickman Wayne State University U S DEPARTMENT OF EDUCATION tit 5ti noseiem 'PERMISSION TO REPRODUCE It-rn 0.. c. THIS F EDUCATIONAL RESOURCES INFORMATION MATERIAL HAS BEEN GRANTED BY CENTER tERICI 0 This document has been reproduced at, D. ci<PIAN received from the person or orgarlitation 17, originating it 13 Minor Changes have been mode to improve repoiductiim Points el view or opinions stated in this To THE EDUCATIONAL RESOURCES document do not necessarily lepresert INFORMATION CENTER IERICI Oficial OEM posilion or policy INDIVIDUAL DIFFERENCES Running Head: 2 BEST COPY AVAILABLE Individual Differences 2 Evolution, Convolution, Dissolution: The Rise of Individual Differences in Human Developmental Psychology Although it is difficult to ascertain precisely the time at which the study of individual differences became recognized as a specialty within the psychological sciences, there appears to be much agreement among historians that its development was fostered primarily within the United States during the late 19th century. It also appears to be generally accepted that the development of this area of research and application is rooted in Darwinian theory (Innis, 1992). Individual differences, according to Walberg and Haertel (1992), became a systematic field of study with the publication Galton, whose of Francis Galton's (1869) book Hereditary Genius. primary interest was the measurement of intelligence in humans, Through his examined the heritable nature of mental abilities. research, Galton hoped for racial improvement, and he set about By proposing that his in an exhaustive mental testing campaign. measurements show a large heritable component in intelligence, This movement proposed that the Eugenics movement was born. through selective breeding, humans could improve the intelligence At this time it was felt (and of their species over time. "supported" through dubious testing procedures) that the more intelligent of peoples were white aristocrats and scientists. 3 Individual Differences 3 Social Darwinism and eugenic ideas and motives served as the impetus for the development of intelligence testing in America in particular, and the emphasis on individual differences in Research in the area of individual differences has had general. tremendous impact on the psychological sciences, albeit having misguided origins and motives. This paper will examin-e the beginnings of research and application concerning individual differences and the social context in which it proliferated. Within this context, the nature versus nurture controversy will be introduced, and a discussion about its relevance to the study of individual differences, and its importance to the field of developmental psychology, will follow. Evolution and Convolution While Charles Darwin's research focused primarily on the behavior of nonhuman species, his ideas developed into an explanatory framework for the understanding of human variability Darwin's ideas were not always and phylogenetic development. fully understood by others, resulting in a proliferation-of convoluted, pseudoscientific philosophies regarding the development of human attributes. Social Darwinism, early mental testing, and the eugenics movement are such examples, which will be discussed after an introduction of Darwin's basic ideas. 4 Individual Differences 4 The principles of Darwinian theory, in brief, are as follows: 1) Humans are all part of the same animal world and there is a continuity of species; 2) This continuity has occurred in nature and not as a result of creation; and 3) There is widespread variation within any given species, resulting in Darwin proposed that a strugq1e-for individual differences. survival exists in humans and other animals which results in the natural selection of the most fit organisms over time, therefore, certain variations are more likely to survive than others. Darwin defined fitness in humans as the reproductive success of an individual; the better able the organism is to reproduce, the on to its offspring. more adaptive characteristics are passed Darwin's premise that humans are a part of the same animal world and that there is a continuity of species served to further Darwin experimentation in the area of comparative psychology. proposed that man had evolved from apes and that studies of primate behavior could provide an evolutionary window through which humans could better understand the development of their own Between the release of Darwinian theory and the heyday species. of behaviorism in America much research was generated regarding American the phylogenetic distribution of behaviors and traits. Functionalists latched onto practical methodologies in animal 5 Individual Differences 5 Skinner believed that human learning paralleled that research. form of learning demonstrated by rats, due to his belief that rats, like humans, came into the world in a tabula rasa state. Skinner expounded upon Darwin's idea that environmental pressure forced animals to compete and hence, learn adaptive behaviors, and expanded it to identify environmental contingencies Of reinforcement as the powers which shape individual behavior. Tolman, another animal researcher, focused on purposive behavior in animals, with the assumption that animals have the capacity to acquire new behaviors which could serve as adaptive given a niche in which the behaviors enhanced survival (Innis, 1992). The Darwinian concept of variation within any given species has influenced psychology to a great degree, ultimately resulting in an American psychology which has as its cornerstone an emphasis upon the discovery and understanding of individual Social Darwinism, introduced by Herbert Spencer, differences. Spencer, who was emphasized the role of individual differences. described as an "evolutionary associationist" believed that associations made repeatedly between parents and their offspring are passed along through heredity (Hergenhahn, 1992). In referring to human competition, he coined the term "survival of the fittest"; The notion that those individuals with the fittest 6 Individual Differences 6 characteristics will prosper and reproduce was used by the aristocracy to justify their domination over the proletariate This notion perhaps also served as one of the classes. justifications for American settlers to "divide and conquer" the land, without regard for the native Americans who were viewed as inferior beings. James McKeen Cattell, who coined the term "mental test" in 1890, utilized Wundt's experimental principles and extensions of Galton's anthropometric tests toward advancing mental testing. Strongly influenced by Galton, Cattell was convinced that variations in mental processes could be objectively measured by As described in von Mayrhauser (1992), psychophysical methods. Cattell defined the accuracy of his tests in relation to other Cattell tests and hence, equated validity with reliability. proposed a form of "mental energy" as underlying all mentality These and argued that it is predictive of academic abilities. theories were not supported through the replication method; In fact, one of Cattell's own students, Clark Wissler, used' correlational methods to demonstrate the tests' low correlation with academic performance. The concept of a unitary intelligence was of special Lewis Terman interest among researchers in the United States. 7 Individual Differences 7 coined the term IQ, or intelligence quotient, to serve as an The deterministic beliefs that general index of general ability. should be ability is largely inherited and that instruction geared toward the needs of the superior students served as twentieth guiding principles in the educational policy of early Was the Indeed, during this time, determinisin century America. human prevailing ideological orientation toward understanding influence of development, with little or no recognition of the Individual human environment on a child's capacity to learn. insofar as the development was viewed as a predetermined process, innate individual could only progress as far as his or her Here the IQ was believed to be the capabilities would allow. quality manifestation of these innate capabilities, a stable uninfluenced by environmental conditions. spawned from such Early attempts to measure intelligence was United With the increase of immigration to the philosophies. trend of States during the early 1900's came an increasing to-identify government-endorsed testing campaigns which purported Physical capabilities. and classify emigrants according to their during this attributes of individuals were often overemphasized genetic endowment period due to the prevailing belief that poor (Hergenhahn, 1992). in turn led to poor physical condition 8 Individual Differences 8 Physical characteristics provided convenient indices of measurement in the absence of well-researched intelligence tests, and it is not unlikely that during this time many children were inappropriately labeled as "feebleminded" on the basis of Many Southeastern European physical characteristics alone. immigrants arriving at Ellis Island were classified aS mentally deficient based on similar, culturally biased procedures. In American schools, due in large part to social Darwinism and eugenic philosophies, remedial programs such as special education were not in the mainstream of schooling due to the belief that child anomalies were part of the natural social order and that society would benefit more from the education of the more "fit" children (Fagan, 1992). Dissolution Late nineteenth and early twentieth century conceptions of human development were characterized by two ideological The notion that individual development is determined viewpoints. primarily by inherited, or innate, qualities was embraced by people who maintained higher positions in the social hierarchy. An opposing view, held by people of lower social status, favored These dichotomous environmental influences on development. viewpoints epitomized the nature-nurture controversy, which Individual Differences 9 continues to permeate the study of individual differences today. From the nature-nurture debate in developmental psychology have emerged issues which ultimately led to the serious questioning of social Darwinian and eugenic principles. We will now discuss these issues, limited to those involving the development of intelligence. The first issue to be discussed here is the notion of the variability hypothesis of intelligence. The functionalists, adhering to their interpretation of Darwinian principles, believed that men represented the extremes of the normal distribution of abilities whereas the female population was In other words, more idiots and somewhere in the middle. The functionalists further believed that the geniuses were men. reason for the under-representation of women in institutions for the mentally-defective was that there is a smaller number of Likewise, the reason for female under- "dumb" females. representation in the universities and in powerful, influential roles throughout history was believed by the functionalists to be the result of a smaller number of "very smart" females. Also, women were believed to be intellectually inferior simply because they infrequently attained eminent positions in society. These notions were used to justify gender discrimination in social 10