What do intelligence scores predict

Another criticism lies in the use of intelligence and standardized tests as predictive measures for social outcomes. Researchers have learned that IQ and general intelligence g correlate with some social outcomes, such as lower IQs being linked to incarceration and higher IQs being linked to job success and wealth.

However, it is important to note that correlational studies only show a relationship between two factors: they give no indication about causation.

As a result, critics of intelligence testing argue that intelligence cannot be used to predict such outcomes, and that environmental factors are more likely to contribute to both IQ test results and later outcomes in life. The controversy surrounding using intelligence and standardized tests as predictive measures for social outcomes is, at its core, an ethical one.

Consider the implications if employers decided to use intelligence tests as a way to screen prospective employees in order to predict which individuals will be successful in a job. This misapplication of intelligence testing is considered unethical, because it provides a measure for discriminating against fully qualified individuals.

Again, even if intelligence scores correlate with job success, this does not mean that people with high intelligence will always be successful at work. Another criticism points out that standardized tests that actually measure specific skills are misinterpreted as measures of intelligence. Researchers examined the correlation between the SAT exam and two other tests of intelligence and found a strong relationship between the results.

They concluded that the SAT is primarily a test of g or general intelligence. However, correlational studies provide information about a relationship, not about causation. Critics of standardized tests also point to problems associated with using the SAT and ACT exams to predict college success.

Predicting college success is most reliable when a combination of factors is considered, rather than a single standardized test score. A similar controversy surrounding the use of intelligence tests surrounds whether or not these tests are biased such that certain groups have an advantage over other groups.

Questions of bias raise similar questions to the questions around whether intelligence tests should be used to predict social outcomes. For example, the relationship between wealth and IQ is well-documented.

Could this mean that IQ tests are biased toward wealthy individuals? Or does the relationship go the other way? If there are statistically significant group differences in IQ, whether based on race, gender, socioeconomic status, age, or any other division, it is important to take a look at the intelligence test in question to make sure that there are no differences in testing method that give one group an advantage over others along any dimension other than intelligence.

Additionally, IQ cannot be said to describe or measure all possible cultural representations of intelligence. Various cultures value different types of mental abilities based on their cultural history, and the IQ test is a highly westernized construct.

As such, IQ tests are also criticized for assessing only those particular areas emphasized in the western conceptualization of intelligence, such as problem-solving, and failing to account for other areas such as creativity or emotional intelligence.

IQ tests are often criticized for being culturally biased. A study stated that IQ tests may contain cultural influences that reduce their validity as a measure of cognitive ability for Mexican-American students, indicating a weaker positive correlation relative to sampled white American students. Other recent studies have questioned the culture-fairness of IQ tests when used in South Africa. Standard intelligence tests, such as the Stanford-Binet, are often inappropriate for children with autism, and may have resulted in incorrect claims that a majority of children with autism are mentally retarded.

Privacy Policy. Skip to main content. Search for:. Measuring Intelligence. History of Intelligence Testing Intelligence testing has evolved over time as researchers continually seek the best method for measuring intelligence. Learning Objectives Trace the history of intelligence testing. Key Takeaways Key Points The Wechsler scales were the first intelligence scales to base scores on a standardized normal distribution. The Stanford-Binet Intelligence Scale formed the basis for one of the modern intelligence tests that remains in common use.

Critics claim that environmental factors, such as quality of education and school systems, lead to cultural discrepancies in test scores. Key Terms intelligence quotient : A score derived from one of several different standardized tests attempting to measure intelligence.

IQ Tests IQ tests are used to measure human intelligence quotient as measured against an age-based average intelligence score. Learning Objectives Explain how IQ scores are measured on a normal curve. It is more likely, however, that environmental factors contribute to both IQ scores and to outcomes in life. Current IQ tests measure personal scores based on standard deviations from a well-established average, and are thought to be relatively stable over time.

IQ tests are psychometric and person-centric tests that are statistically reliable and valid, but do not necessarily represent the same type of intelligence across cultures. IQ tests are often criticized for being biased, and for only measuring one aspect of intelligence.

Waller has shown, for example, that sons whose IQ scores are above those of their fathers also tend to achieve a higher social class status; conversely, those with scores below their fathers' tend to achieve lower status.

Such an effect is not surprising, given the relation between IQ scores and years of education reviewed in Section II. In section II we noted that intelligence test scores predict occupational level, not only because some occupations require more intelligence than others but also because admission to many professions depends on test scores in the first place. There can also be an effect in the opposite direction, i.

Kohn and Schooler , who interviewed some men in various occupations farmers, managers, machinists, porters Although the issue of direction of effects complicates the interpretation of their study, this remains a plausible suggestion.

A generation ago these were substantial in the United States, averaging about six IQ points or 0. All these changes can be regarded as increasing the "complexity" of the rural environment in general or of farm work in particular. However, processes with a genetic component, e. Attendance at school is both a dependent and an independent variable in relation to intelligence. On the one hand, children with higher test scores are less likely to drop out, more likely to be promoted from grade to grade and then to attend college.

Thus the number of years of education that adults complete is roughly predictable from their childhood scores on intelligence tests. On the other hand schooling itself changes mental abilities, including those abilities measured on psychometric tests. This is obvious for tests like the SAT that are explicitly designed to assess school learning, but it is almost equally true of intelligence tests themselves.

The evidence for the effect of schooling on intelligence test scores takes many forms Ceci, When children of nearly the same age go through school a year apart because of birthday-related admission criteria , those who have been in school longer have higher mean scores. Children who attend school intermittently score below those who go regularly, and test performance tends to drop over the summer vacation.

A striking demonstration of this effect appeared when the schools in one Virginia county closed for several years in the s to avoid integration, leaving most Black children with no formal education at all. Compared to controls, the intelligence-test scores of these children dropped by about 0.

Schools affect intelligence in several ways, most obviously by transmitting information. The answers to questions like "Who wrote Hamlet? Perhaps at least as important are certain general skills and attitudes: systematic problem-solving, abstract thinking, categorization, sustained attention to material of little intrinsic interest, repeated manipulation of basic symbols and operations. There is no doubt that schools promote and permit the development of significant intellectual skills, which develop to different extents in different children.

It is because tests of intelligence draw on many of those same skills that they predict school achievement as well as they do. To achieve these results, the school experience must meet at least some minimum standard of quality.

In very poor schools, children may learn so little that they fall farther behind the national IQ norms for every year of attendance.

When this happens, older siblings have systematically lower scores than their younger counterparts. This pattern of scores appeared in at least one rural Georgia school system in the s Jensen, Before desegregation, it must have been characteristic of many of the schools attended by Black pupils in the South. In a study based on Black children who had moved to Philadelphia at various ages during this period, Lee found that their IQ scores went up more than half a point for each year that they were enrolled in the Philadelphia system.

Intelligence test scores reflect a child's standing relative to others in his or her age cohort. Very poor or interrupted schooling can lower that standing substantially; are there also ways to raise it? In fact many interventions have been shown to raise test scores and mental ability 'in the short run" i.

One noteworthy example of at least short-run success was the Venezuelan Intelligence Project Hermstein et al, , in which hundreds of seventh-grade children from underprivileged backgrounds in that country were exposed to an extensive, theoretically based curriculum focused on thinking skills.

The intervention produced substantial gains on a wide range of tests, but there has been no follow-up. Children who participate in "Head Start" and similar programs are exposed to various school-related materials and experiences for one or two years.

Their test scores often go up during the course of the program, but these gains fade with time. By the end of elementary school, there are usually no significant I9 or achievement-test differences between children who have been in such programs and controls who have not.

There may, however, be other differences. Follow-up studies suggest that children who participated in such programs as preschoolers are less likely to be assigned to special education, less likely to be held back in grade, and more likely to finish high school than matched controls Consortium for Longitudinal Studies, ; Darlington, ; but see Locurto, More extensive interventions might be expected to produce larger and more lasting effects, but few such programs have been evaluated systematically.

The test scores of the enrichment-group children were already higher than those of controls at age two; they were still some five points higher at age twelve, seven years after the end of the intervention. Importantly, the enrichment group also outperformed the controls in academic achievement. Family environment. No one doubts that normal child development requires a certain minimum level of responsible care.

Severely deprived, neglectful, or abusive environments must have negative effects on a great many aspects of development, including intellectual aspects.

Beyond that minimum, however, the role of family experience is now in serious dispute Baumrind, ; Jackson, ; Scarr, , Psychometric intelligence is a case in point. Do differences between children's family environments within the normal range produce differences in their intelligence test performance? The problem here is to disentangle causation from correlation. These findings suggest that differences in the life styles of families whatever their importance may be for many aspects of children's lives make little long-term difference for the skills measured by intelligence tests.

We should note, however, that low-income and non-white families are poorly represented in existing adoption studies as well as in most twin samples. Thus it is not yet clear whether these surprisingly small values of adolescent c 2 apply to the population as a whole. It re-mains possible that, across the full range of income and ethnicity, between-family differences have more lasting consequences for psychometric intelligence.

There has been only one major study of the effects of prenatal malnutrition i. Stein et al analyzed the test scores of Dutch year-old males in relation to a wartime famine that had occurred in the winter of , just before their birth. In this very large sample made possible by a universal military induction requirement , exposure to the famine had no effect on adult intelligence.

Note, however, that the famine itself lasted only a few months; the subjects were exposed to it prenatally but not after birth. In contrast, prolonged malnutrition during childhood does have long-term intellectual effects.

These have not been easy to establish, in part because many other unfavorable socioeconomic conditions are often associated with chronic malnutrition Ricciuti, ; but cf. Sigman, In one intervention study, however, pre-schoolers in two Guatemalan villages where undernourishment is common were given ad lib access to a protein dietary supplement for several years.

A decade later, many of these children namely, those from the poorest socio-economic levels scored significantly higher on school related achievement tests than comparable controls Pollitt et al, It is worth noting that the effects of poor nutrition on intelligence may well be indirect.

Malnourished children are typically less responsive to adults, less motivated to learn, and less active in exploration than their more adequately nourished counterparts.

Certain toxins have well established negative effects on intelligence. Exposure to lead is one such factor. In one long-term study McMichael et al, ; Baghurst et al, , the blood lead levels of children growing up near a lead smelting plant were substantially and negatively correlated with intelligence test scores throughout childhood. No "threshold dose" for the effect of lead appears in such studies. Although ambient lead levels in the United States have been reduced in recent years, there is reason to believe that some American children - especially those in inner cities - may still be at risk from this source cf.

Alcohol Extensive prenatal exposure to alcohol which occurs if the mother drinks heavily during pregnancy can give rise to fetal alcohol syndrome, which includes mental retardation as well as a range of physical symptoms. Smaller "doses" of prenatal alcohol may have negative effects on intelligence even when the full syndrome does not appear. Streissguth et al found that mothers who reported consuming more than 1. Prenatal exposure to aspirin and antibiotics had similar negative effects in this study.

Perinatal Factors. Complications at delivery and other negative perinatal factors may have serious consequences for development.

Nevertheless, because they occur only rarely, they contribute relatively little to the population variance of intelligence [Broman et al, Down's syndrome, a chromosomal abnormality that produces serious mental retardation, is also rare enough to have little impact on the overall distribution of test scores.

The correlation between birth weight and later intelligence deserves particular discussion. In some cases low birth weight simply reflects premature delivery; in others, the infant's size is below normal for its gestational age. Both factors apparently contribute to the tendency of low-birth-weight infants to have lower test scores in later childhood Lubchenko, These correlations are small, ranging from.

The effects of low birth weight are substantial only when it is very low indeed less than gm. Premature babies born at these very low birth weights are behind controls on most developmental measures; they often have severe or permanent intellectual deficits Rosetti, Although it is simplest to describe the gains as increases in population IQ, this is not exactly what happens.

Most intelligence tests are "re-standardized" from time to time, in part to keep up with these very gains. As part of this process the mean score of the new standardization sample is typically set to again, so the increase more or less disappears from view. In this context, the Flynn effect means that if twenty years have passed since the last time the test was standardized, people who now score on the new version would probably average about on the old one.

The sheer extent of these increases is remarkable, and the rate of gain may even be increasing. The scores of nineteen-year-olds in the Netherlands, for example, went up more than 8 points--over half a standard deviation-between and What's more, the largest gains appear on the types of tests that were specifically designed to be free of cultural influence Flynn, One of these is Raven's Progressive Matrices, an untimed non-verbal test that many psychometricians regard as a good measure of g.

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