Concepts of environment and intelligence in psychology. (2023)

Environmental and intelligence research examines the influence of the environment on intelligence. This is one of the most important factors in understanding differences between human groups in IQ test scores and other measures of cognitive ability. Historically, in the field of intelligence research, there has been much interest in determining environmental influences on the development of cognitive functions, particularly fluid intelligence, defined by its stabilization at 16 years of age.

Neurobiological Theory

As babies, our neural connections are completely undifferentiated. Neurons establish connections with neighboring neurons, and these become more complex and idiosyncratic as the child grows, until age 16, when this process stops. This is also the time frame for the development of what is defined in psychometric studies as the general intelligence factor, or g, as measured by IQ tests. It is said that a person's IQ is relatively stable after reaching maturity.

The brain's ability to adapt its connections to environmental stimuli declines over time, so there is also a critical period for intellectual development. While the critical period for the visual cortex ends in early childhood, other cortical areas and abilities have a critical period that lasts until maturity (16 years), the same period for the development of fluid intelligence. In order for a person to develop certain intellectual capacities, they must receive the appropriate environmental stimuli during childhood before the critical phase of adaptation of their neural connections is over. It should be noted that some researchers believe that the critical period effect is a result of the way in which intellectual abilities are acquired, that changes in neural connections inhibit or prevent possible future changes. However, the critical period is observed in all people of approximately the same age, regardless of the level of intellectual ability reached.

environmental influences

cultural partner

family

Access to home resources and a learning-friendly family life definitely affect intelligence test scores. However, it is difficult to separate possible genetic factors from, for example, parental attitude or language use.

Peer Group

JR Harris suggested in The Nurture Assumption that an individual's peer group strongly influences their intelligence over time, and that different peer group characteristics may explain the difference in IQ between blacks and whites. Several longitudinal studies support the idea that peer groups significantly affect academic performance, but relatively few studies have examined the effects on tests of cognitive ability. However, there is some evidence that peer groups influence tests of cognitive ability.

Education

Education has a complicated relationship with intelligence; is a dependent and independent variable. For one thing, those who did better on intelligence tests during childhood tend to have lower dropout rates and complete more years of school, making intelligence a predictor of how well someone will do in later life. the school. However, on the other hand, education has been shown to improve a person's performance on these intelligence tests from a very early age.

training and interventions

Research on the effectiveness of interventions and the extent to which fluid intelligence can be increased, particularly after the age of 16, is somewhat controversial. Fluid intelligence is typically viewed as something more innate and defined as immutable after maturity. However, a recent article shows that fluid intelligence can be increased, at least for a period of time, by training to increase an adult's working memory capacity. Working memory capacity is defined as the ability to recall something temporarily, e.g. B. Remember a phone number long enough to dial it.

In one experiment, groups of adults were tested for the first time using standard fluid intelligence tests. They then trained groups over four different days, each for half an hour, with an N-back exercise that worked to improve working memory. It supposedly does this through a few different components, which involve ignoring irrelevant elements, managing tasks simultaneously, and monitoring performance during training while connecting related elements. Following this training, the groups were retested and those with training (compared to untrained control groups) showed significant improvements in fluid intelligence test performance.

environmental enrichment

From a neurobiological perspective, environmental enrichment affects cognition and intellectual development. In one experiment, four different habitats were established to test how environmental enrichment or relative impoverishment affects rats' performance on different measures of intelligent behavior. First, the rats were isolated, each in its own cage. In a second condition, the rats were still isolated, but this time they had an enriching toy or object with them in the cage. The third condition placed the rats in cages together to receive social enrichment without any enrichment objects. The fourth and final condition exposed the rats to both social interaction and some form of object enrichment.

When measuring intellectual ability, rats with both forms of enrichment performed better, with those with social enrichment coming in second best, and those with a toy in their cage performing even better than rats without toys or other mice. When rat cortex volume was measured, the amount of accumulation again correlated with greater volume, which is indicative of more synaptic connections and higher intelligence.

biological influences

nutrition

It has long been believed that prenatal malnutrition can lead to deficits in intellectual development. However, a study of Dutch people born during the wartime famine showed that short-term prenatal malnutrition was not related to intellectual development.

However, long-term postnatal malnutrition can have a significant impact on intellectual development. This relationship has been more difficult to establish because the problem of malnutrition is often confused with socioeconomic problems. However, it has been shown in some studies where preschool children in two Guatemalan towns (where malnutrition is common) received protein supplements for several years, and even in the lowest socioeconomic class, these children showed increased performance in intelligence tests, relative to controls without dietary supplements.

Early nutrition can affect brain structures that actually correlate to IQ scores. In particular, the caudate nucleus is particularly affected by early environmental factors and its volume is correlated with IQ. In an experiment by Isaacs et al. assigned preterm infants to a standard or nutritious diet in the weeks immediately after birth. When subjects were tested later in adolescence, the high nutrient group was found to have significantly larger caudate volumes and performed significantly better on verbal IQ tests. This study also found that the extent to which caudate volume size was selectively related to verbal IQ was much higher in male participants and not very significant in females. This may help explain the finding from other previous research that the effects of early nutrition on intelligence are predominant in men.

Another study by Lucas et al. confirms the conclusions about the importance of nutrition for the cognitive development of preterm infants. Men's cognitive function was also found to be significantly more affected by postnatal malnutrition. However, a unique finding was that those fed the non-nutrient-enriched formula experienced a higher incidence of cerebral palsy.

Breastfeeding has long been claimed to provide essential nutrients to a premature infant and has been correlated with greater cognitive achievement later in life. However, this effect has also been demonstrated in normal weight infants. Controlling for other environmental influences and maternal IQ, a study by Johnson et al. it even found that initiation of breastfeeding predicted three-year-olds' scores on intelligence tests. On average, breastfeeding resulted in a 4.6 higher score on intelligence tests.

Exposure to toxic chemicals and other substances.

Lead exposure has been shown to have a significant impact on a child's intellectual development. In a long-term study by Baghurst et al. In 1992, children who grew up near a lead shack had significantly lower intelligence test scores that were negatively correlated with blood lead concentration. Although lead levels in our environment have been reduced, some areas of the United States, particularly inner cities, are still at risk of exposure to your children.

In addition, prenatal alcohol exposure can seriously affect a child's performance on tests of intelligence and intellectual growth. At high doses, fetal alcohol syndrome, which causes intellectual disability and other physical symptoms, such as facial and head deformities, heart defects, and slow growth, can develop. An estimated 1 in 1,000 babies born in the general population are born with fetal alcohol syndrome as a result of excessive alcohol use during pregnancy.

However, studies have shown that even at slightly lower doses, prenatal alcohol exposure can affect a child's developing intelligence without the full syndrome being present. A 1989 study by Streissguth, Barr, Sampson, Darby, and Martin showed that moderate prenatal doses of alcohol, defined as drinking 1.5 oz. daily, reduced children's test scores by 4 points below control values ​​at four years of age. They also showed that prenatal exposure to aspirin and antibiotics was also correlated with lower performance on intelligence tests.

In another study, prenatal drug exposure was shown to have significantly negative effects on cognitive function, measured at five years of age, compared with controls matched for socioeconomic status and urban setting. The researchers concluded that children exposed to drugs before birth are at increased risk of learning difficulties and attention problems at school and therefore should be targeted for interventions to support educational success. It can be hypothesized that the effect of these drugs on prenatal brain development and axonal guidance may be at the root of the negative consequences of later deficits in intellectual development.

In particular, prenatal marijuana exposure influences intelligence development later in childhood in a nonlinear manner with exposure level. Heavy maternal use in the first trimester is associated with lower scores for verbal reasoning on the Stanford-Binet intelligence scale; heavy use during the second trimester is associated with deficits in short-term compound memory and lower scores on quantitative tests; high exposure in the third quarter was also associated with lower quantitative scores.

perinatal factors

There is also evidence that complications of childbirth and other factors related to the timing of birth (perinatal) can have a serious impact on intellectual development. For example, prolonged periods without access to oxygen during labor can lead to brain damage and intellectual disability. Additionally, low birth weight has been linked to lower intelligence scores later in life for children. There are two reasons for low birth weight: premature birth or the baby's height slightly below average for gestational age; both contribute to intellectual deficits later in life. However, the correlations are relatively small unless the weight is extremely low (less than 1500 g), then the impact on intellectual development is more severe, often leading to intellectual disability.

genius development

It has been hypothesized that the development of genius in an area is the result of early environmental exposure to the subject in which the "genius" has prodigious knowledge or skill. This uses the definition of genius, which is not just a well-above-average IQ score, but also having exceptional understanding or special ability in a particular area. Einstein is often used as an example of genius; When he was a child, he did not display exceptional general intelligence, however, there is evidence that he began to explore ideas of physics and the universe at a very early age.

This fits the model of fluid intelligence development before adulthood, as neural connections are still made in childhood. The idea is that if you expose a child to theoretical physics concepts, for example, before their brain stops responding to the environment in plastic ways, then by adulthood you will gain an exceptional understanding of this area because a framework has been developed for it. in early childhood. However, Garlick suggests that early environmental experience with his genius realm is necessary but not sufficient for genius development.

There are many environmental influences on intelligence, typically divided into biological and non-biological factors, often including social or cultural factors. The common element between these two divisions is early childhood exposure. It seems that exposure to these various influences, positive or negative, on the level of intelligence, defined as the fluid intelligence most commonly measured by IQ tests, must occur early in brain development, before the connections cease. neurons, to be effective. to form.

Education

Training at an early age reduces synaptic pruning, which helps save neurons.

Musical

Early musical training in children is said to improve IQ. However, one study claimed that music training improves verbal IQ but not spatial IQ. Significant differences in brain structure were found between musicians and non-musicians.

Studies have shown that listening to Mozart before an IQ test improves scores. This is called the Mozart effect. The Mozart Effect improves spatiotemporal thinking.

Chess

Studies have shown that chess requires auditory* (can't find this reference)-verbal-sequential skills, not visual-spatial skills. A German study found that Garry Kasparov, a former Soviet-Russian world chess champion considered by many to be the greatest chess player of all time, has an IQ of 135 and an extremely good memory. One study found that students who took chess classes improved their math and conceptual skills.