Influence of Intelligence on Social Mobility: Can Your IQ at the Age of 11 Predict Your Social Class at Midlife?

Written by Nea Lulik, MSc in Psychology of Individual Differences

Social status attainment and therefore social class mobility in adulthood are of interest to psychologists, sociologists, political scientists, economists, epidemiologists and many more. The reason behind the interest is because it indicates access to material goods, educational opportunities, healthy environments, and nonetheless the economic growth. It is important to study childhood ability, childhood social background, and education because they are important determinants to adult social status (Deary, et al., 2005) (Deary, Whiteman, Starr, Whalley, & Fox, 2004) (Johnson, Brett, & Deary, 2010b) (Johnson, Brett, & Deary, 2010a) (Breen & Goldthorpe, 2001) (von Stumm, Gale, Batty, & Deary, 2009).

Deary and colleagues (Deary, et al., 2005) did a study that encompassed a wide range of data of individuals in lifetime (in childhood and during mid-adulthood). Most of the Scottish children which were born in 1921 participated in the Scottish Mental Survey 1932, which was conducted under the auspices of the Scottish Council for Research in Education (SCRE, 1933) and obtained the data of psychometric intelligence of Scottish pupils (Deary, Whiteman, Starr, Whalley, & Fox, 2004). The number of children who took the mental ability test (based on the Moray House tests) was 87,498. They were between age 10 and 11. The tests covered general, spatial and numerical reasoning.

At mid-life period, a subset of the subjects participated in one of the Midspan studies, which were large health studies of adults and were carried out in Scotland in the 1960s and 1970s. The particular Midspan study they took part in was the Collaborative study of 6022 men and 1006 women, conducted between 1970 and 1973 in Scotland. Participants completed a questionnaire (participant’s address, father’s occupation, the participant’s own first regular occupation, the age of finishing full time education, number of siblings, and if the participant was a regular car driver) and attended a physical examination (measurement of height). Social class was coded according to the Registrar General’s Classification (1966) for the participant’s occupation at the time of screening, his first occupation and his father’s occupation. Six social classes were used (I – professional to V – lowest, manual work). Women were excluded from the data set due to the unrepresentativeness of the social spectrum.

A correlation and structural equation model analysis was conducted (Deary, et al., 2005). In the structural equation models, social status in the 1970s was the main outcome variable. The main contributors to education (and first social class) were father’s social class and IQ at age 11, which was also found in a Scandinavian study (Sorjonen, Hemmingsson, Lundin, & Melin, 2011). This effect was direct and also mediated via education and the participant’s first job.

Participants at midlife did not necessarily ended up in the same social class as their fathers (Deary, et al., 2005). There was social mobility in the sample: 45% of men were upwardly mobile, 14% were downwardly mobile and 41% were socially stable. IQ at age 11 had a graded relationship with participant’s social class. Same effect was seen for father’s occupation. Men at midlife social class I and II (the highest, more professional) also had the highest IQ at age 11. Height at midlife, years of education and childhood IQ were significantly positively related to upward social mobility, while number of siblings had no significant effect. For each standard deviation increase in IQ score at the age 11, the chances of upward social mobility increases by 69% (with a 95% confidence interval of 30% to 120%). After controlling the effect of independent variables, only IQ at age 11 was significantly inversely related to the downward in social mobility. Which means that more years of education help a man to surpass his father’s social class, and that low IQ makes a man prone to fail behind his father’s social class.

Higher IQ at age 11 was also significantly related to higher social class at midlife, higher likehood car driving at midlife, higher first social class, higher father’s social class, fewer siblings, higher age of education, being taller and living in a less deprived neighbourhood at midlife (Deary, et al., 2005)(see figure above). IQ was significantly more strongly related to the social class in midlife than the social class of the first job.

Finally, height, education and IQ at age 11 were predictors of upward social mobility and 0nly IQ at age 11 and height were significant predictors of downward social mobility (Deary, et al., 2005). Number of siblings was not significant in neither of the models.

Another research (Johnson, Brett, & Deary, 2010a) looked into the pivotal role of education in association between ability and social class attainment through three generations (fathers, participants and offspring) using the SMS1932 (Deary, Whiteman, Starr, Whalley, & Fox, 2004)(Lothian Birth Cohort 1921) educational data, childhood ability and late life intellectual function data. It was proposed that social class of origin acts as a ballast (Johnson, Brett, & Deary, 2010a), restraining otherwise meritocratic social class movement, and that education is the primary means through which social class movement is both restrained and facilitated – therefore acting in a pivotal role.

It was found (Johnson, Brett, & Deary, 2010a) that social class of origin predicts educational attainment in both the participant’s and offspring generations. 

Father’s social class and participant’s social class held the same importance in predicting offspring educational attainment – effect across two generations. Educational attainment mediated the association of social class attainments across generations (father’s and participants social class, participant’s and offspring’s social class). There was no direct link social classes across generations, but in each generation educational attainment was a predictor of social class, which is consistent with other studies (Nettle, 2003) (Forrest, Hodgson, Parker, & Pearce, 2011). Also, participant’s childhood ability moderately predicted their educational and social class attainment (.31 and .38). Participant’s educational attainment was strongly linked with the odds of moving downward or upward on the social class ladder. For each SD increase in education, the odds of moving upward on the social class spectrum were 2.58 times greater (the downward ones were .26 times greater). Offspring’s educational attainment was also strongly linked with the odds of moving upward or downward on the social class ladder. For each SD increase in education, the odds of moving upward were 3.54 times greater (the downward ones were .40 times greater). In conclusion, education is very important, because it is the fundamental mechanism functioning both to hold individuals in their social class of origin and to make it possible for their movement upward or downward on the social class ladder (Johnson, Brett, & Deary, 2010a).

In the Cohort 1936 it was found that regarding whole generations (not individuals) (Johnson, Brett, & Deary, 2010b) the social mobility between father’s and participant’s generation is: 50.7% of the participant generation have moved upward in relation to their fathers, 22.1% had moved downwards, and 27.2% had remained stable in their social class. There was a lack of social mobility in the offspring generation as a whole. However, there was definitely individual offspring movement on the social class ladder: 31.4% had higher social class attainment than their participant parents (grandparents), 33.7% moved downward, and 33.9% stayed stable. Participant’s childhood mental ability was linked to social class in all three generations. A very important pattern has also been confirmed: average years of education increased with social class and IQ.

There were some great contributors to social class attainment and social class mobility in the twentieth century: Both social class attainment and social mobility are influenced by pre-existing levels of mental ability (Johnson, Brett, & Deary, 2010b), which was in consistence with other studies (Nettle, 2003; Waller, 1971; Young & Gibson, 1963; Burt, 1961). So, the role of individual level mental ability in pursuit of educational attainment – professional positions require specific educational credentials. Furthermore, educational attainment contributes to social class attainment through the contribution of mental ability to educational attainment. Ever further, mental ability can contribute to social class attainment independent of actual educational attainment, as in when the educational attainment is prevented, individuals with higher mental ability manage to make use of the mental ability to work their way up on the social ladder. This study made clear that intergenerational transmission of educational attainment is one of the key ways in which social class was maintained within family, and there was also evidence that education attainment was increasing over time. Finally, the results suggest that social mobility (moving upward and downward) has increased in recent years in Britain. Which according to Burt (Burt, 1961) is important because an overall mobility of about 22% is needed to keep the distribution of intelligence relatively constant from one generation to the other within each occupational category.

References:

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Intelligence: is your social class important when it comes to inequalities in health, and how?

Written by Nea Lulik, MSc in Psychology of Individual Differences

Virtually all indicators of health favour people of higher socio-economic status (SES). SES and health outcomes are generally consistent with time, place, disease, and health-care system and are finely graded up the SES continuum. This article argues that general intelligence (g) is the fundamental cause for health inequality.

g is a highly general ability and it plays a big role in performing a job well and getting ahead, socio-economically. g can influence individuals’ behaviour, as well as society’s social, political and economic outcomes. Because of these generalizations in various areas, g can be assessed as a predictor to explain these outcomes. The author refers to this network of generalizations and related predictions as g theory.

The main questions are:

Do the data of daily self-maintenance, health self-care, prevention of accidental injury conform to the predictions of g theory? Does g theory explain the social class differences in health better than can conventional theories of social inequality?

Conventional theories of social inequality presuppose that social class disparities in health are due to the material resources, such as access to medical care. But in the countries that made improvements in the health system and made it equal for everyone, the results show, that greater equalization of health care results in even wider social class disparities.

The argument is that g is the fundamental cause because it meets six criteria that every candidate for the cause must meet: stable distribution over time, is replicable, is a transportable form of influence, has a general effect on health, is measurable, and is falsifiable. It has been proven that g meets all but the fourth criteria – g’s general effect on heath knowledge, behaviour and outcomes. 

Income, occupation, education, health literacy (efficient learning, reasoning, problem solving) are strong correlates of health outcomes.

g is content- and content-free ability to process information of any sort. The high generality of g is also seen in the more specific skills and abilities that specify a high-g person (reasoning, conceptual thinking, problem solving, and quick and efficient learning) – all these general-purpose abilities are applicable to any task or life setting. g predicts job performance to some extent (in an indirect way), especially when the job isn’t closely supervised and it does not follow a routine, and it requires lots of novel problem solving, planning and decision making. Experience and favourable trait can compensate to a certain extent for lower levels of g, but they can never negate the disadvantages of information processing that is slow or error prone.

National Adult Literacy Survey (NALS) measures performance on simulated daily tasks involving written material, which are essential for one to participate effectively in modern society. It resembles the test for general intelligence, and all the skills that are tested, are prototypical manifestations of g. Comparing the NALS test to IQ reveals the same pattern of effects.

Not all people learn equally well when exposed to the same instructions, because higher g promotes faster, more extensive and more complete learning of what is being taught. Also, information processing is involved in all daily tasks, so higher g always provides an edge. Therefore, inadequate thinking skills can result in health problems.

Age-specific rates of illness and death are often two/three times higher in the lower class strata. Greater access to medical care has surprisingly little relation to differences in health. Equalizing the availability of health care does not equalize its use. Less educated and lower income individuals seek preventive health care less often than better educated or higher income people, even when care is free. Health depends more on private precaution and healthy lifestyle (healthy choices about our own behaviour), than on medical care. 

Rates of illness and death are progressively lower at higher social ranking. Graded relation between class and health is found regardless of whether social class is measured by level of education, occupation, or income.

The six criteria (that g is the fundamental):

· Stability: Equalizing socio-economic environments does little to nothing to reduce the dispersion in IQ (Frikowska et al., 1978, in Gottfredson, 2004). The dispersion of IQ in a society in general is more stable, than its dispersion of socio-economic advantage (Plomin et al., 2001, in Gottfredson, 2004).

· Replicability: Siblings who differ in IQ also differ in socio-economic success to about the same degree as do strangers of comparable IQ (Jencks, et al., 1979; Murray, 1997, 1998, in Gottfredson, 2004). Also, g theory predicts that if genetic g is the principal mechanism transmitting socioeconomic inequality from one generation to the next, then the maximum correlation between parent and child SES will be close to their genetic correlation for IQ, which is about .50. Intergenerational SES correlations have remained stable despite improvements in social conditions.

· Transportability: The performance and functional literacy (NALS studies) studies both illustrate how g represents a set of highly generalised reasoning and problem-solving skills. g seems to be linearly related to performance in school, jobs and achievements.

· Generality: Studies show that IQ measured at the age of 11 predicted longevity, cancers, dementia, and functional independence more than 60 years later (Deary et al., 2004, in Gottfredson, 2004).

· Measurability: g factor can be extracted from any broad set of mental tests and has provided a common, reliable ground for measuring general intelligence in any population. Among the usual indicators of class, years of education is the most g loaded because it correlates .68 with IQ, whereas occupation and income correlate .50 and .35 with IQ (Jencks et al., 1972, in Gottfredson, 2004).

· Falsifiability: g theory would conceive health self-care as a job, a set of instrumental tasks performed by the individuals, so it would predict g to influence health performance in the same way as it predicts performance in education and work.

Now, chronic illnesses are the major illnesses in developed countries today, and their major risk factors are health habits and lifestyle. The higher social strata knows the most and the lower social strata knows the least, whether class is assessed by education, occupation or income and even when the information seems to be most useful for the poorest. Education was the best predictor in this case again. Higher g promotes more learning, it increases exposure to learning opportunities and then allows for their fuller exploitation. 

Health literacy predicts health knowledge, health behaviour and health

The problem is not in the lack of access to care, but the patient’s failure to use it effectively when delivered. Some patients are unable to understand even the simple information about their disease. Low literacy has been associated with low use of preventive care, poor comprehension of one’s illness, and delay in seeking screening for cancer – even when care is free.

Health literacy reflects mostly g – TOFHLA test – similar to NALS except is for health

TOFHLA literacy is similar to functional literacy and work literacy (mostly g). Low literacy remains a significant disadvantage even when people receive instructions in what they are motivated to learn. These results are consistent with the job performance research, as in training and experience help, but do not neutralize the disadvantage of low g. 

Health self-management is important because literacy provides the ability to acquire new information and complete complex tasks and that limited problem solving abilities make low-literacy patients less likely to change their behaviour on the basis of new information. Chronic lack of good judgement and effective reasoning leads to chronically poor self-management. With the technology, the self-care is becoming more complex, and therefore high g people will benefit more than lower g patients.

Accidental injury and death: Some people tend to have more accidents than others even with the same level of exposure to the same hazards in the same environment. The risk of accidents is higher in workers with fewer years of experiences and less knowledge, and when the tasks are more complex, novel or confusing. Errors increase when tasks demand higher cognitive abilities. 

People in lower class neighbourhood are more prone to higher risks of accidents but not intended deaths. Higher mortality in higher class is only present in one category – aircraft accidents. Risk of death by lightening is also more common in lower class neighbourhood. People in the poorer neighbourhood are also more likely to be murdered than those in middle class area. The risk of death by fire is also more common in poorer than richer neighbourhood, especially for children and elderly.

There is something about life in lower social class that increases vulnerability in general.

The more personal choices we have in conducting our life as we see fit, the more our fate depends on our own knowledge, judgement and foresight – hence, g. All accidents are amenable to some control, and same as with jobs, the higher the g the better the outcome. Technological and social advance greatly increase both the complexity of our life and the choices we have. Although we welcome more choice, both choice and complexity put a big premium on g. 

Reference: 

Gottfredson, L. S. (2004). Intelligence: Is it the Epidemiologists' Elusive "Fundamental Cause" of Social Class Inequalities in Health? Journal of Personality and Social Psychology, 174-199.