자료: Wikipedia, http://en.wikipedia.org/wiki/Nature_versus_nurture
The nature versus nurture debates concern the relative importance of an individual's innate qualities ("nature", i.e. nativism, or innatism) versus personal experiences ("nurture", i.e. empiricism or behaviorism) in determining or causing individual differences in physical and behavioral traits.
The view that humans acquire all or almost all their behavioral traits from "nurture" is known as tabula rasa ("blank slate"). This question was once considered to be an appropriate division of developmental influences, but since both types of factors are known to play such interacting roles in development, many modern psychologists consider the question naive - representing an outdated state of knowledge.[1][2][3][4][5] Psychologist Donald Hebb is said to have once answered a journalist's question of "which, nature or nurture, contributes more to personality?" by asking in response, "which contributes more to the area of a rectangle, its length or its width?"[6][7][8][9]
For a discussion of nature versus nurture in language and other human universals, see also psychological nativism.
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[edit]Scientific approach
In order to disentangle the effects of genes and environment, behavioral geneticists perform adoption and twin studies. Behavioral geneticists do not generally use the term "nurture" in order to explain that portion of the variance for a given trait (such as IQ or theBig Five personality traits) that can be attributed to environmental effects. Instead, two different types of environmental effects are distinguished: shared family factors (i.e., those shared by siblings, making them more similar) and nonshared factors (i.e., those that uniquely affect individuals, making siblings different). In order to express the portion of the variance that is due to the "nature" component, behavioral geneticists generally refer to the heritability of a trait.
With regard to the Big Five personality traits as well as adult IQ in the general U.S. population, the portion of the overall variance that can be attributed to shared family effects is often negligible.[10] On the other hand, most traits are thought to be at least partially heritable. In this context, the "nature" component of the variance is generally thought to be more important than that ascribed to the influence of family upbringing.
In her Pulitzer Prize-nominated book The Nurture Assumption, author Judith Harris argues that "nurture," as traditionally defined in terms of family upbringing does not effectively explain the variance for most traits (such as adult IQ and the Big Five personality traits) in the general population of the United States. On the contrary, Harris suggests that either peer groups or random environmental factors (i.e., those that are independent of family upbringing) are more important than family environmental effects.[11][12]
Although "nurture" has historically been referred to as the care given to children by the parents, with the mother playing a role of particular importance, this term is now regarded by some as any environmental (not genetic) factor in the contemporary nature versus nurture debate. Thus the definition of "nurture" has been expanded in order to include the influences on development arising from prenatal, parental, extended family and peer experiences, extending to influences such as media, marketing, and socio-economic status. Indeed, a substantial source of environmental input to human nature may arise from stochastic variations in prenatal development.[13][14]
Philosophical difficulties
[edit]Are the traits real?
It is sometimes a question whether the "trait" being measured is even a real thing. Much energy has been devoted to calculating the heritability of intelligence (usually the I.Q., or intelligence quotient), but there is still some disagreement as to what exactly "intelligence" is.
[edit]Biological determinism
If genes do contribute substantially to the development of personal characteristics such as intelligence and personality, then many wonder if this implies that genes determine who we are. Biological determinism is the thesis that genes determine who we are. Few if any scientists would make such a claim;[21] however, many are accused of doing so.
[edit]Is the problem real?
Many scientists feel that the very question opposing nature to nurture is a fallacy. Already in 1951, Calvin Hall in his seminal chapter[22] remarked that the discussion opposing nature and nurture was fruitless. If an environment is changed fundamentally, then the heritability of a character changes, too. Conversely, if the genetic composition of a population changes, then heritability will also change. As an example, we may use phenylketonuria (PKU), which causes brain damage and progressive mental retardation. PKU can be treated by the elimination of phenylalanine from the diet. Hence, a character (PKU) that used to have a virtually perfect heritability is not heritable any more if modern medicine is available. Similarly, within, say, an inbred strain of mice, no genetic variation is present and every character will have a zero heritability. If the complications of gene-environment interactions and correlations (see above) are added, then it appears to many that heritability, the epitome of the nature-nurture opposition, is "a station passed".[23]
History of the nature versus nurture debate
Traditionally, human nature has been thought of as not only inherited but divinely ordained. Whole ethnic groups were considered to be, by nature, superior or inferior. In the 19th and 20th centuries, however, intellectuals increasingly attributed differences among races, classes, and genders to socialization (nurture), rather than to innate qualities (nature). In the 20th century, the Nazis pursued an agenda based on the concept of human nature as defined by one's race. The Communists, on the other hand, largely followed Marx's lead in defining the human identity as subject to social structures, not nature. In scientific circles, this conflict led to ongoing controversy of sociobiology and evolutionary psychology.[citation needed]
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