The Role of Intelligence
in Mobility & The Bell
Curve Controversy
M. Cohen, B. Talekar, V. Wang
SOCI230
Spring 2004
29 March
OUTLINE

What is intelligence?

How is it measured?

Bases for Intelligence
Correlates of Intelligence

(largely with respect to ethnicity)

Responses and Critiques

Implications of theories and research?
WHAT IS INTELLIGENCE?
The study of variation in intelligence across
different population groups became a subject of
study in the last half of the nineteenth century

The classicists (intelligence as a structure) –
“The Bell Curve”

The revisionists (intelligence as information
processing)

The radicals (the theory of multiple intelligences)
WHAT IS INTELLIGENCE?
Galton – correlation coefficient (1888)
 Spearman – g & s factors (Two factor theory of
intelligence)
 Binet - age-graded tests
 Thomson – different conceptualization of g
 Thurstone – refuted the g factor; separate
intellectual abilities unrelated to each other
“The effort to dislodge g has been less than
successful”

HOW IS INTELLIGENCE MEASURED?
Concepts
 Psychometric approach (“Cognitive classes”)
 Multiple forms of intelligence (e.g., Gardner,
Sternberg)
 Cultural variation in concepts of intelligence
 Developmental progressions (e.g., Vygotsky,
Piaget)
 Biological approaches
HOW IS INTELLIGENCE MEASURED?


Numerous attempts to measure it have been
discounted – acts of racism, political reaction,
political bungling, and scholarly fraud.

Timed tests that measure speed of cognitive tasks

Choice reaction time

Inspection time

Neurological measures
Problems of interpretation, unanswered questions
BASIS FOR INTELLIGENCE:
Genetics


Behavior genetics (misnomer)

study of the genetic and environmental influences on a
trait

understand the sources of variation in a phenotypic
characteristic - score on an intelligence test
Research on twins and families to understand the
genetic and environmental influences on
development and change in intelligence
BASIS FOR INTELLIGENCE:
Genetics

Studies on twins




MZ twins genetically identical
DZ twins no more similar to each other than siblings
Conceptual and empirical problems in studying
twins
Studies

Twins reared together and apart

Separated MZ twins encounter more varied environments than
MZ and DZ twin pairs reared together – yet they are somewhat
more alike in IQ than DZ twins reared in the same family
BASIS FOR INTELLIGENCE:
Family environment

Studies of the relationship between IQ scores of adopted
children and their biological and adopted parents

Danish fathers (Teasdale & Owen, 1984)

Texas Adoption Study (Horn, Loehlin & Willerman, 1979)

The Colorado Adoption Project (Plomin & DeFries, 1985)
BASIS FOR INTELLIGENCE:
Family environment

The biological background of adopted
children influences the IQ of these children

The biological background of the adopted
child more important in determining the IQ of
the older child than the characteristics of the
adoptive families
BASIS FOR INTELLIGENCE:
Family environment
Conclusions:
 The heritability of IQ increases with age from infancy
to adulthood
 Between family environmental influences decline with
age – they are hardly detectable over wide ranges of
the environment for adult samples
 Phenotypic continuity on IQ is substantially influenced
by genetic continuity
 Genetic influences on IQ not expressed at an earlier
age may influence IQ at a later age
 Genotype X environment interactions are not an
important source of influence on the development of
IQ
BASIS FOR INTELLIGENCE:
Social environment

Is it possible to increase cognitive ability?



Other known factors



Nutrition: may be linked, but not well understood
Special programs (i.e., Head Start): only minor/temporary effects
Culture: Corr (ethnicity, IQ) falls to ~0 when accounting for
sociocultural factors
Improvements in the economic circumstances, in the
quality of the schools attended, in better public health and
perhaps also in diminishing racism may be narrowing the
gap (H&M, p. 270, 292) …but the authors don’t seem
convinced.
Attempts to raise intelligence – by altering the social and
physical environment – is one of high hopes, flamboyant
claims, and disappointing results…the problems of low
cognitive ability are not going to be solved by outside
interventions (p.387,389).
CORRELATES OF INTELLIGENCE:
Gender
Brody
 Gender differences in intellectual ability are
small to virtually non-existent
 Secular changes are attributed to narrowing
the gender gap in special ability scores, with
an implication that secular changes in culture
may have something to do with this (i.e., sex
stereotyping of activities, curricular choices)
CORRELATES OF INTELLIGENCE:
Ethnicity & Race


Brody presents studies with conflicting results, and
concludes that we know little about reasons for the
differences in IQ, but reasons may be found in distinctive
cultural experiences.
H&M: Ethnic differences in cognitive ability are real


In terms of IQ score, the trend is generally:
East Asian > White > Black
Refuting evidences of bias:



Predictability of tests – no systematic differences found
Tests’ cultural bias (B/W difference is wider on items
that appear to be culturally neutral than on items that
are culturally loaded).
Ethnic differences in higher education, occupations, and wages
are significantly diminished after controlling for IQ
CORRELATES OF INTELLIGENCE:
SES


Posit: Part of what appears to be an ethnic
difference in IQ scores is actually a socioeconomic
difference.
H&M find that size of the B/W gap shrinks when
socioeconomic status controlled for



SES explains 37% of original B/W differences
IQ scores increase with SES for both races, however, the
magnitude std devs of the B/W differences remain roughly
the same (p. 288)
SES may also be considered a result of cognitive ability
CORRELATES OF INTELLIGENCE:
Education


Intelligence found to be related to academic
performance and number of years of education (Brody)
H&M: After controlling for IQ…larger numbers of blacks
than whites graduate from college

Chances of a 29 y.o. in 1990 having graduated from
college with an IQ of 114
=49% (Latino)
=50% (White)
=68% (Black)

These findings run counter to affirmative action’s assumption
that ethnic groups do not differ in the abilities that contribute to
success in school and workplace (p. 449).
CORRELATES OF INTELLIGENCE:
Occupation & Wages

Individuals with low IQ are not likely to be found in highstatus occupations that require high levels of formal
education as a condition for entry into the occupation


If selection by cognitive ability scores were strictly race
blind...blacks are overrepresented in most occupations,
especially in high-status occupations (medicine,
engineering, teaching)



Individuals with high intelligence are more likely to attain an
occupational status higher than that of their parents (than
those who are low in intelligence) (Brody)
Roughly 6 times as many blacks in teaching and medicine
Over 90% of raw black- and Latino-white wage
differentials disappear after controlling for IQ
Conclusion: IQ score is more important in explaining
B/W occupation and wage differences than are
education and SES for most occupational categories
CORRELATES OF INTELLIGENCE:
Social problems
The worst social problems are heavily concentrated in
the lower portion of the curve.
Controlling for IQ
Poverty
differences, but not completely
Unemployment / labor participation
L/W diff by 73%; B/W diff by 65%
Marriage
Little change. W women more likely
to marry
Illegitimacy
L/W diff by 44%, B/W diff by 20%
Welfare recipiency
L/W diff by 84%, B/W diff by ~50%
Crime
B/W diff by 75%
Herrnstein & Murray’s prescription
for change…


Education: Current measures of success are intended for
average to below-average students, letting the gifted get away
without ever developing their potential
 Solution: Fund reallocation to decrease funds focused on the
disadvantaged and increase budget for gifted programs
Affirmative action: The manner in which it is currently practiced
has lost touch with any reasonable understanding of the logic
and purposes of affirmative action (p. 468)
 Issue relates to the difference between “ethnic equity” and
“competitive fairness”
 Affirm action fosters differences in the distribution of academic
ability across races on college campuses
 After controlling for IQ, it’s difficult to demonstrate that the US still
suffers from racial discrimination in occupations and pay
 Solution: abolish its use in college admissions and in the
workplace.
Herrnstein & Murray’s predictions
for future



Old stratifications are fading, replaced by a greater reliance on “merit”.
Hence, the rise of the “cognitive elite” – a status acquired via high IQ
(implying that social background, ethnicity, and money would serve as
obstacles toward its attainment).
The rich vs. the intellectuals: the affluent will constitute a major portion
of the population and they will increasingly consist of the most talented
population (p. 517).
The underclass: Out-migration of the cognitively best individuals out of
lower class neighborhoods and settings. This will exacerbate the
conditions of the underclass. The cognitive elite will come to consider
the underclass as in their condition through no fault of their own, but
due to inherent shortcomings about which little can done. Because the
underclass cannot be trusted to make wise decisions for themselves
(i.e., to use cash wisely), the cognitive elite will develop social welfare
policies primarily in the form of services rather than cash…policies of
custodialism. This has implications on the socio-demographic make-up
of communities, state and federal budgets, centralization of
governance. The population of the underclass will continue to grow.
Racial tensions will re-emerge.
Cracking the Bell Curve Myth:
An overview
“Americans have created the extent and type of
inequality we have, and Americans maintain
it” (p.7)

Inequalities among Americans are not
inevitable

Inequality is a social construction; not solely
determined by genetic endowments
Cracking the Bell Curve Myth:
The problem with psychometrics
Psychometrics – main assumptions

The fundamental skill critical to human
functioning is “intelligence”

General intelligence (g) is “a general capacity for
inferring and applying relationships”

People must rank in a bell curve
Cracking the Bell Curve Myth:
Information-processing approach
Intelligence “…is mental self-management” (p.47)
[quote from Robert Sternberg]

Intelligence can be taught and trained

Measurement tools test intellectual process

New research tests everyday problem solving

Adds new insights to psychometrics
Cracking the Bell Curve Myth:
What do IQ tests measure?
“Intelligence is what intelligence tests measure” (p.27)
[quote from Arthur Jensen]

“Screw-up” attitudes and luck

Exposure to curricula, not intelligence

Tests are limited in their ability to predict how people
apply their knowledge in practical situations
Cracking the Bell Curve Myth:
Reanalysis of the NLSY data

Bell Curve errors in the analysis





Missing information
Unreliable parental SES scale
Inappropriately weighted parental SES variables
Omitted variable bias
Corrected findings

Parental home environment, community context,
educational attainment, and gender are more
accurate predictors of poverty than nature
Cracking the Bell Curve Myth:
Systems of inequality
“America’s level of inequality is by design. It is not by
nature, nor by the distribution of its people’s talents,
nor by the demands of the Western market.” (p.125)



Between WWII and 1970 inequality decreased, then
widened in the early 1970s and through the 1980s
These changes cannot be explained by individual
inherited characteristics (e.g., intelligence)
U.S. has greater degree of income inequality than
any other developed nation, but inequality is not
necessary for economic growth
Cracking the Bell Curve Myth:
America’s policy choices

Policies to reduce poverty




AFDC, school lunches, food stamps, etc.
Most successful among elderly, while many
children are left poor
Americans less supportive of such programs than
citizens of other affluent nations
Subsidizing the middle class

Health care, tax deductions for families,
subsidizing homeownership
Cracking the Bell Curve Myth:
America’s policy choices, cont’d.

Subsidizing the wealthy


Regulating the labor market


Corporate welfare, tax laws
Union rules, plant relocation, wage setting
Enriching intelligence




Quality of schooling affects rates of learning
Biased track placement in schools
Summer vacations
Job structure affects adult development
Cracking the Bell Curve Myth:
Race, ethnicity, and intelligence
“A racial or ethnic group’s position in society
determines its measured intelligence rather
than vice versa.” (p.173)

Koreans in Japan; Polish Jews in 1920s US

History matters: Africans and Mexicans in US

Inequality and discrimination continue today
Cracking the Bell Curve Myth:
Subordination & low performance

Socioeconomic deprivation

Segregation concentrates and accentuates
disadvantages

Stigma of inferiority prompts attitudes of
resignation and rebellion
IMPLICATIONS/DISCUSSION




Of the various social outcomes and behaviors analyzed,
which ones present the case for a strong causal role of IQ and
which ones present weak cases?
Is equality a utopian ideal in the US? What kind of equality
are we talking about here?
With regard to finding valued places/position in society
according to intelligence, is there a link between Herrnstein &
Murray’s work and Parsons?
What are the methodological barriers to testing the theoretical
frameworks introduced in the readings?


Are there other (mediating) factors related to intelligence,
differences in ethnicity, and social strata that this week’s authors
discounted or failed to acknowledge?
Implications of works on social policies of today and the
future?
Mainstream Science on
Intelligence (Gottfredson,1994)
1.
2.
3.
4.
5.
6.
7.
Intelligence is a very general mental capability; not
merely book learning (1)
Intelligence can be, and is, measured well (2)
The spread of people along the IQ continuum can
be represented well by the bell curve (4)
Intelligence tests are not culturally biased (5)
IQ is probably more strongly related to individual
outcomes than any other single trait (9)
Individuals differ in intelligence due to both their
environments and genetic heritage, but genetics
plays a bigger role (14)
IQ’s gradually stabilize during childhood (16)