Both pop-psychology and modern psychology generally assert that a person’s early environment is critical for their long-term development. Although there are a few prominent dissenters, such as Judith Rich Harris, people’s intuitions animal studies, and modern knowledge of neurology all seem favorable to this conclusion. There are a number of popular but generally debunked proposals for helping children to improve their cognitive capabilities, several that seem promising but have received little attention, and a very few that have been fairly well established as actually working.
One particularly popular instance of the first class in recent years is that the exposure of young children to Mozart, or possibly to classical music more generally will improve their IQ. The motivation for this myth is presumably the desire to assert the objective superiority of “high culture” over “low culture”, but the actual studies suggesting the effect were weak and have been refuted. IQ itself is also a controversial measure in much of society, and psychologists have legitimate differences of opinion regarding the scope of its impact. Modern psychology makes it clear however that while some of what we consider ‘intelligence’, especially creativity, curiosity, and social skills, generally falls outside of the rubric covered by IQ, and while specific intellectual abilities vary greatly among people at any given IQ, IQ is still a very useful predictor of life outcomes, and comes much closer to matching our intuitive concept of intelligence than any other concept we can measure does.
Some promising research supports, and little seems to debunk, the claim that supplementing the normal dietary supply of childbearing women with certain nutrients such as choline and folic acid can slightly improve youthful cognitive ability. In the case of choline, animal studies also strongly suggest that it can almost eliminate the normal cognitive decline associated with aging, though there is little evidence that it is effective at preventing Alzheimer’s disease. Substantial amounts of human cognitive decline also result from strokes, which can best be prevented through healthy lifestyles among the elderly. Supplementation of the supply of nutrients present in an ordinary diet should be entirely safe unless doses many times greater than could be achieved through diet are used. Other speculative but safe methods for improving children’s mental abilities include infantile training in sign language or slightly later training in tonal languages.
The consumption of fish, preferably oily fish, by pregnant and nursing mothers is essentially the only extremely well supported option for improving cognitive ability. In a recent study, it was found that children of mothers who exceeded the maximum fish consumption recommended in US governmental guidelines while pregnant were substantially more intelligent than those who consumed no fish and slightly more intelligent than those who consumed some fish but less than the recommended limit. All other well-substantiated activities of large effect are already common in Western nations, but because of their great importance and incomplete adherence they bear repetition. Breast milk is extremely important for adequate brain development, and more consistent breast feeding would probably be the single most significant thing that could be done to improve the mental abilities of developed world populations. Lead and mercury substantially stunt children’s intellectual development, as does inadequate early life consumption of iodine or maternal consumption of iron. Neglect and inadequacy of stimulus also seriously impair infant development, but maximizing the is optimal for them, feedback from the infant should be used to determine the optimal level of stimulus. Finally, the risk of mental retardation due to Downs Syndrome rises with the mother's age, especially for mothers older than 35, so if financial circumstances permit it is significantly safer to have children at a relatively young age.