Why is g so deeply insinuated in
social inequality?
Linda S. Gottfredson, PhD
School of Education
University of Delaware, USA
International Society for the Study of Individual Differences
London, July 26, 2011
1
Total-Evidence Rule forces opposing
explanations to compete head-on
The 2 competitors—
• Social privilege theory
• Useful tool theory
2
Competing explanations for pervasive, persisting IQ-SES links
1.
Social privilege theory
a.
b.
c.
d.
IQ differences result mostly from differences in family privilege
Higher IQ and education does not reflect “merit,” but social class in disguise.
Higher level jobs do not require more intelligence to perform well
If everyone had equal opportunities in life, all could perform well and social
inequality would disappear. Unequal outcomes signals unequal opportunity
to develop & use cognitive talent.
Privilege perpetuates itself by pretending to be “merit”
2.
Useful tool theory
a.
b.
c.
d.
IQ differences result mostly from differences in genetic heritage.
Higher g level reflects stronger learning & reasoning ability.
Higher g enhances performance in all jobs, but especially more complex
ones.
If everyone had equal opportunities in life, people would perform to very
different levels and create social inequality. Equal outcomes would require
unequal opportunity to develop & use cognitive talent.
Human cognitive variation guarantees moderate social inequality in any complex, free society3
Total evidence rule
• All types of evidence
–
–
–
–
–
Tasks, ages, type inequalities
Psych, bio, neuro
Exper, observational
Pheno & geno
Variance, covariance, changes in
• Novel predictions
• Pattern of results
–
–
–
–
Consistent
Consilient
Mechanistic
No opportunistic omissions
Individual differences (IDs) at issue
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
Opportunities,
Opportunities,
barriers
Income level
(dollars)
gg
(within
(withinage)
age)
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Occupation level
(prestige)
Personality
Personality
(“bigfive”)
five”)
(“big
* ages --
GENES
Education level
(years completed)
Academic performance
(within grade)
Job performance
(within occupation)
Causal claims—“social privilege” theory
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
Opportunities,
Opportunities,
barriers
Income level
(dollars)
gg
IQ age)
(within
(withinage)
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Occupation level
(prestige)
Personality
Personality
(“bigfive”)
five”)
(“big
* ages --
GENES
Education level
(years completed)
Academic performance
(within grade)
Job performance
(within occupation)
Causal claims—“useful tool” theory
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
Opportunities,
Opportunities,
barriers
Income level
(dollars)
gg
(within
(withinage)
age)
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Occupation level
(prestige)
Personality
Personality
(“bigfive”)
five”)
(“big
* ages --
GENES
Education level
(years completed)
Academic performance
(within grade)
Job performance
(within occupation)
Which set is most consistent with the full body of
evidence?
• Sample of 9 opposing predictions
• Evidence from different fields
o Psychometrics
o
o
o
o
Job analysis
Personnel selection
Neuroscience
Behavior genetics
• Results replicated
8
1. IDs in intelligence: Trait or socially constructed?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
Opportunities,
Opportunities,
barriers
barriers
SHARED
(“family”)
NONSHARED
SP
UT
Variation in genotypes:
GENES
Occupation level
(prestige)
Income level
(dollars)
Socially
Personality
Personality
(“bigfive”)
five”)
generated
(“big
g
g trait
A human
(within
age)
(within age)
* ages --
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Education level
(years completed)
Academic performance
(within grade)
Job performance
(within occupation)
Variation highly structured, not socially constructed
Its phenotypic structure appears to be replicated at genetic level
g
More
heritable
V
Q
S
Privilege
0
Useful tool
1
M
Others
10
2. Adult trajectory: Social or biological?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Opportunities,
Opportunities,
barriers
gg
(within
(withinage)
age)
* ages --
GENES
UT
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Occupation level
(prestige)
Income level
(dollars)
Personality
Personality
(“bigfive”)
five”)
(“big
SP
Variation in genotypes:
Education level
(years completed)
Adding
knowledge
Biological
Academic performance
decline
(within
grade)
Job performance
(within occupation)
Fluid g rises, then falls with biological age
All fluid abilities move in tandem
Privilege
0
0
Useful tool
1
1
IQ 100
12
3. Trajectory of IQ heritability—up or down?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Opportunities,
Opportunities,
barriers
gg
(within
(withinage)
age)
* ages --
GENES
UT
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Occupation level
(prestige)
Income level
(dollars)
Personality
Personality
(“bigfive”)
five”)
(“big
SP
Variation in genotypes:
Education level
(years completed)
Down
Up performance
Academic
(within grade)
Job performance
(within occupation)
Genetic portion of IQ variation rises with age
Family SES contributions to IQ variation wash away
Privilege
0
0
0
Useful tool
1
1
1
14
4. How does intelligence get into the brain?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
SP
Opportunities,
Opportunities,
barriers
Education
Variation in genotypes:
Income level
(dollars)
gg
(within
(withinage)
age)
* ages --
UT
Specific skills,
Genes
abilities
ecific skills,
lities, habits
Figure 1
Occupation level
(prestige)
Personality
Personality
(“bigfive”)
five”)
(“big
NONSHARED
GENES
Education level
(years completed)
Academic performance
(within grade)
Job performance
(within occupation)
g is genetically enmeshed in brain physiology
Privilege
0
0
0
0
Useful tool
1
1
1
1
(genetic)
16
5. Are higher jobs really more cognitive?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
Opportunities,
Opportunities,
barriers
No
Occupation level
(prestige)
UT
Income level
(dollars)
Yes
gg
(within
(withinage)
age)
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Education level
(years completed)
Personality
Personality
(“bigfive”)
five”)
(“big
* ages --
GENES
SP
Academic performance
(within grade)
Job performance
(within occupation)
The work is more complex
Privilege
0
0
0
0
0
Useful tool
1
1
1
1
1
18
6. Does g really predict job performance?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
Opportunities,
Opportunities,
barriers
Personality
Personality
(“bigfive”)
five”)
(“big
SP
No
gg
UT
(within
age)
(within age)
Yes
* ages --
GENES
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
Education level
(years completed)
Academic performance
(within grade)
Occupation level
(prestige)
Income level
(dollars)
Job performance
(within occupation)
predictive
validity of g
The work is more complex
.8
Privilege
0
0
0
0
0
0
Useful tool
1
1
1
1
1
1
.5
.2
20
7. Do social outcomes have genetic component?
Background
Influences
Personal
Attributes
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
Opportunities,
Opportunities,
barriers
Personality
Personality
(“bigfive”)
five”)
(“big
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
SP
No
Education level
(years completed)
UT
Occupation level
(prestige)
Income level
(dollars)
Yes
gg
(within
IQ age)
(within
age)
* ages --
GENES
Socioeconomic Outcomes: Social Rungs & Task Performances
Academic performance
(within grade)
Job performance
(within occupation)
Social outcomes moderately heritable
% heritable:
% jointly with IQ:
Acad
achiev
Privilege
0
0
0
0
0
0
0
Useful tool
1
1
1
1
1
1
1
60-70
50
Yrs
educ
40-50
Health
Occ
level
Subjective
well-being
22
8. Is IQ-outcome covariation entirely social?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Opportunities,
Opportunities,
barriers
Education level
(years completed)
Personality
Personality
(“bigfive”)
five”)
(“big
Occupation level
(prestige)
Income level
(dollars)
Yes
SP
Variation in genotypes:
gg
(within
IQage)
(within
age)
* ages --
GENES
Specific skills,
abilities
ecific skills,
lities, habits
Figure 1
UT
Academic performance
No
(within grade)
Job performance
(within occupation)
Covariation also moderately heritable
% heritable:
% jointly with IQ:
Acad
achiev
Privilege
0
0
0
0
0
0
0
0
Useful tool
1
1
1
1
1
1
1
1
60-70
40
50
25
Yrs
educ
40-50
20
Health
Occ
level
Subjective
well-being
24
Covariation also moderately heritable
% heritable:
% jointly with IQ:
Acad
achiev
Privilege
0
0
0
0
0
0
0
0
Useful tool
1
1
1
1
1
1
1
1
60-70
40
50
25
Yrs
educ
40-50
20
Health
Occ
level
Subjective
well-being
Also—
Predictions about geno components of covariance with g
25
9. Can equal training or experience eliminate IQperformance link?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
GENES
Opportunities,
Opportunities,
barriers
Privilege
0
0
0
0
0
0
0
0
0
Useful tool
1
1
1
1
1
1
1
1
1
Education level
(years completed)
Occupation level
(prestige)
Income level
(dollars)
Personality
Personality
(“bigfive”)
five”)
(“big
gg
(within
(withinage)
age) SP
* ages -Specific skills,UT
abilities
ecific skills,
lities, habits
Yes
Academic performance
(within grade)
Job performance
(within occupation)
No
g remains predictive—always need to learn & reason
Figure 1
9. Can equal training or experience eliminate IQperformance link?
Background
Influences
Personal
Attributes
Socioeconomic Outcomes: Social Rungs & Task Performances
Variation in environments:
barriers
SHARED
(“family”)
NONSHARED
Variation in genotypes:
GENES
Opportunities,
Opportunities,
barriers
Privilege
0
0
0
0
0
0
0
0
0
Useful tool
1
1
1
1
1
1
1
1
1
Education level
(years completed)
Occupation level
(prestige)
Income level
(dollars)
Personality
Personality
(“bigfive”)
five”)
(“big
gg
(within
(withinage)
age) SP
* ages -Specific skills,UT
abilities
ecific skills,
lities, habits
Yes
Academic performance
(within grade)
Job performance
(within occupation)
No
g remains predictive—always need to learn & reason
Figure 1
Also—
novel predictions on social interventions aimed at changing variance or covariance
Nomological network for biological,
functional link
• All types of evidence
–
–
–
–
–
Tasks, ages, type inequalities
Psych, bio, neuro
Exper, observational
Pheno & geno
Variance, covariance, changes in
• Novel predictions
• Pattern of results
–
–
–
–
Consistent
Consilient
Mechanistic
No opportunistic omissions
Thank you