For the better part of a century, child development studies have revolved around a central queEstion How much of a child mental abilityis determincd by naturcthe genes he inherits from his parents and how much depends on nurture, the shaping intluences of the people and things that surround himm
A hundred years ago, people generally assumed that intcilectual potential was fixed at birth: A child was destined by nature to be bright of dull, regardless of the effects of his cnvironment or training Thinking on this point shifted during the early years of the 20th century, when Sigmund Freud, the father of psychoanalysis, first popularized the idea that early childhood experience was critical to an individual's later development. Freud's theories propelled the pendulum toward an emphasis on cnvironment, and scholars began examining the effects of nurture on a child's mental abilities. Was it possible that early intervention, in the form of teaching and other focused attention, could actually increase a child's brain power?
Certainly, such techniques had produced spectacular results in some extreme situations. In a number of celebrated cases, researchers noted that children made astonishing intellectual gains when they were taken out of opPpressive institutional settings or disadvantaged homes and placed in foster homes where they received the benefits of a normal family life. These results scemed to send a clear message: Nurturing can enhance mental performance.
In later studies using laboratory animals, researchers found evidence Suggesting that concentrated training might actually physically in crease brain power. One famous cxperiment divided pairs of twin ratsinto two groups: Those in the first group were kept together and treated to a life of toys and exercise equipment, learning challenges and rewards for performance, and frequent field trips to explore unfamiliar environments. Their twin brothers, meanwhile, were kept in solitary cages and denied Such stimulating experiences. Not only did the favored rats outscore their siblings on problem-solving intelligence tests the scientists found that the animals had also developed larger, heavier brains as a result of the stimulation they had experienced.
Skeptics are quick to point out, however, that the development of human children cannot be cquated with that of rats, and that there is no hard evidence that forced learning in early childhood has any lasting effects. Furthermore, some experts warn that the potential harm outweighs any educational gains children might derive from this hot house approach to child rearing.
A related controversy is the timing of a young child's learning experiences. Some psychologists maintain the Freudian view that experiencesauring the first three years of life have an effect on a youngster's development that can never be undone. Others consider this far too drastic View and contend that a loving, nurturing environment can produce positive results whenever the child experiences it, overriding earlier negative infucnces. By the same token, they believe, an environment that discourages learning can counteract the effeects of earlier positive gains, Both sides point to the decidedly mixed lessons of Project Head Start perhaps the most significant large-scale effort to apply the potential-boosting theories of the environmentalists into the lives of real children.
Launched in the 1960s, Head Start is a class-room enrichment program designed to provide an educational boost to preschool children from disadvantaged backgrounds. Theinitial results looked promising: When children from the program first entered school, they performed better than comparable youngsters who had not attended Head Start. But after a year or two, they lost the edge they had gained and once again slipped behind the performance level of classmates from more advantaged Circumstances. Many experts concluded that for educational enrichment efforts to be effective inthe long term, they must be reinforced by influences in the home environment and the societyin which the child is growing up.
Today, the nature versus nurture pendulum sits squarely in the middle: Heredity and environment both play a critical role in determining a child's ability to learn. In the broadest possible terms, it might be said that heredity sets an upper limit on a child's potential, and environmental experiences determine thhe extent to which that potential is realized. This is to say, for example, that a child who is born retarded will only develop intellectual abilities up to a certain low level, however encouraging an environment he inhabits; and a child born with a capacity forbrilliance will perform as a genius only if she receives the environmental stimulation necessary to develop her natural mental ability.
However, this neat model does nothing to explain how nature and nurture interact. Scientists who are exploring the many ways in which the two forces are intertwined note that there is active interplay between the individual and his environment at every stage of development. Not only does the child develop capabilities in response to his environment, it seems the environment responds to the child's inborn traits as well. One group of studies showed that infants born with pleasant, casy dispositions received better care and more stimulating attention from their parents than did infants with more difficult temperaments. ACcording to this pattern, naturally outgoing children may inefect improve their ovwn learning environments, while children born with more fearful or reticent personalities will avoid certain types of interaction that are potential learning experiences.