Heritability of intelligence 3pdf
1
Socioeconomic status Grading of parent occupa0on into five categories: Mackintosh (1998) and Mascie Taylor (1984) • Class I: Professional occupa0ons • Class II: Managerial & technical occupa0ons • Class III: Skilled occupa0ons: Manual (M) and unmanual (U) • Class IV: Partly skilled occupa0ons; • Class V: Unskilled occupa0ons. Children whose fathers had Class I occupa0ons scored 10 IQ points higher than those with fathers in the Class V occupa0ons (Wahlsten, 1997) Adop0on studies: children coming from low socioeconomic backgrounds who moved to a family with high socioeconomic status had an IQ scores improvement of 1216 points. Confluence model: the context of the family situa0on to explain intellectual intelligence. Zajonc (1976): there are factors that influence the rela0onship between birth order and intelligence. First borns do not have to share their parents a[en0on at first. Concordance Rates Ridley (1999) shows the concordance rate of IQ (presence of the same intelligence level between 2 individuals). This is consistent with several studies, which were used to make es0mates of the heritability of intelligence: • Eysenck (1979): es0mate of 69%. • Herrnstein and Murray (1994): es0mate of 74%. Gene0c influence may be lower than these previous es0ma0ons. More modern es0mates of heritability fall into a range: • Neisser et al. (1996) es0ma0ng 40 to 80% of intelligence is inherited. • Mackintosh (1998) es0mate 30 to 75%. • The commonly accepted es0mate is 50% (Chipeur et al., 1990). Outside Family Factors Five nonshared factors outside the family that can influence intelligence (Harris, 1995): 1. Contextspecific socialisa;on As children age, the family environment has less impact and outside family factors have more impact. 2. Outsidethehome socialisa;on Children can iden0fy with many social groups, and each group will have a different influence on their intelligence. 3. Transmission of culture via group processes Social norms learnt from the family are only kept and shared by the individual if they are accepted by the social groups they belong to. 4. Group processes that widen differences between social groups Social norms are not only formed from fidng in with a group, but from perceived differences of other groups whose features are rejected 5. Group processes that widen differences among individuals within the group The roles within a group will influence intelligence Genetics Heritability of intelligence examines whether and to what extent intelligence is passed down through genes. • Children biologically inherit 50% of their genes from the mother and 50% from the father during concep0on. • Variability is the difference between a parent’s and child’s intelligence. It is assessed by looking at the propor0on of shared variance. High propor0ons (100%) suggests no variance between parent and child. This variance accounted for by gene0cs is the average es0mate. • Does not mean that 50% of intelligence is inherited exactly from one parent, but popula0onwise this is the case. • Intelligence is suscep0ble to environmental influence as well, so an es0mate of heritability is calculated (h 2 ). • Three main types of studies are used to compare gene0c and environmental influences on intelligence: family studies, adop0on studies & twin studies Education Stephen Ceci (1990, 1991) • Metaanalysis effects of a[endance on intelligence test scores. • Overall finding were that children who a[end school regularly scored higher on intelligence tests than those who a[ended less regularly. • Intelligence test scores among pupils decreased over the long summer holidays. • There was a rise of 2.7 IQ points for each year of schooling. Douglas Wahlsten (1997) • Noted that studies have shown that delays in star0ng school cause intelligence tests scores to drop by 5 IQ points a year. Sorel Cahan and Nora Cohen (1989) • Length of schooling was important in predic0ng performance, more than age, for all the verbal tests. • Length of schooling also made a contribu0on, but a smaller contribu0on, to performance on nonverbal tests. Within family factors Reiss (1997) has implicated three main models to explain how the genes we inherit form behaviours based on the family environments: 1. The passive model: Intelligence is explained by an overlap in genes intelligence occurs because the parent and child share the same genes that influence intelligent behaviour. 2. The childeffects model: Parents react differently to children who demonstrate intellectual behaviours. Harris (1995) suggests that parental response can manifest in two ways: Posi;ve feedback loops (reinforcing the children’s natural intelligence) and Nega;ve Feedback loops (children prevented from behaving consistent with natural intelligence abili0es). 3. Parenteffects model: Parental response to the child influences the development of the child’s behaviour. The child’s intellectual behaviour is driven by their parent’s intellectual behaviour. Twins Due to a failed assassina0on a[empt on Nigel Powers, ‘Dougie’ was presumed to have died in a car explosion. He was then found and adopted by a ‘Belgium boulangerie worker and a fikeen yearold French pros0tute named Chloe who had webbed feet’. Inherited 50% of genes from biological father and 50% from the biological mother. Iden0cal twins who are raised separately have a concordance rate of 76%. Aus0n was raised by his father Nigel Powers. Nigel works as a spy for the Bri0sh Government and shares many similar personality traits. However, Aus0n felt that Nigel focused more on being a friend than a fatherfigure. As a result missed many important moments in Aus0n’s life ‘Daddy wasn’t there’. • Student in the Bri0sh Intelligence Academy • Winner of the Interna0onal Man of Mystery • Interna0onal Super Spy Nigel Powers is a Class I working professional (also a Bri0sh super spy). This meant he could afford to send Aus0n to the Bri0sh Intelligence Academy. Aus0n remained in the care of his father and so is Bri0sh. Living in Britain during the ‘Swinging six0es’ caused his colourful dress sense and dislike of authority figures such as Dr. Evil. Dr. Evil was adopted by Belgians and this is accredited for his evil nature. Dr. Evil’s adop0ve parents are Class V unskilled workers. Which meant that Dr. Evil should have been disadvantaged. However, Dr. Evil a[ended the same school as Aus0n, perhaps though scholarships. • Top student in the Bri0sh Intelligence Academy • Six years of Evil Medical School • Evil genius who has invented numerous evil devices for either world destruc0on or domina0on Inherited 50% of genes from biological father and 50% from the biological mother. Iden0cal twins who are raised separately have a concordance rate of 76%. 87% 86% 76% 55% 47% 40% 31% 24% 0% 0% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Person taking the same IQ test twice Identical twins reared together Identical twins reared apart Fraternal twins reared together Biological siblings reared together Parents and children living together Parents and children living apart Biological siblings reared apart Adopted children living together Unrelated people living apart Level of genetic relatedness IQ concordance rate % • People in Dr. Evil’s life that may have influenced his intelligence are: Number 2, Sco[ Evil, Frau Farbissina, Minime and Mustafa • As leader of his evil organisa0on, the leadership role would have improved his intelligence. Although much of the technical running of the organisa0on is lek to Number 2. • People in Aus0n’s life who may have influenced his intelligence are: Vanessa Kensington, Basil Exposi0on, Felicity Shagwell, Foxxy Cleopatra and Marie Kensington. • Aus0n had a high role within the group, and at 0mes was required to take a leadership role, which would have increased his intelligence Although having an extremely unusual upbringing, Dr. Evil parent’s seem to have encouraged his pursuit of evil. It is likely that posi0ve feedback loops and the s0mula0ng response of his parents developed his intelligence and evil disposi0on. As Aus0n felt that his father was not fully engaged in his upbringing it is hard to tell what influence this had on his intelligence. It is possible he followed his father’s career path in an a[empt to gain recogni0on and respect.
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Transcript of Heritability of intelligence 3pdf
Socioeconomic status
Grading of parent occupa0on into five categories: Mackintosh (1998) and Mascie-‐Taylor (1984) • Class I: Professional occupa0ons • Class II: Managerial & technical occupa0ons • Class III: Skilled occupa0ons: Manual (M)
and unmanual (U) • Class IV: Partly skilled occupa0ons; • Class V: Unskilled occupa0ons. Children whose fathers had Class I occupa0ons scored 10 IQ points higher than those with fathers in the Class V occupa0ons (Wahlsten, 1997) Adop0on studies: children coming from low socioeconomic backgrounds who moved to a family with high socioeconomic status had an IQ scores improvement of 12-‐16 points. Confluence model: the context of the family situa0on to explain intellectual intelligence. Zajonc (1976): there are factors that influence the rela0onship between birth order and intelligence. First borns do not have to share their parents a[en0on at first.
Concordance Rates
Ridley (1999) shows the concordance rate of IQ (presence of the same intelligence level between 2 individuals). This is consistent with several studies, which were used to make es0mates of the heritability of intelligence: • Eysenck (1979): es0mate of 69%. • Herrnstein and Murray (1994): es0mate of
74%.
Gene0c influence may be lower than these previous es0ma0ons. More modern es0mates of heritability fall into a range: • Neisser et al. (1996) es0ma0ng 40 to 80% of
intelligence is inherited. • Mackintosh (1998) es0mate 30 to 75%. • The commonly accepted es0mate is 50%
(Chipeur et al., 1990).
Outside Family Factors
Five non-‐shared factors outside the family that can influence intelligence (Harris, 1995): 1. Context-‐specific socialisa;on As children age, the family environment has less impact and outside family factors have more impact. 2. Outside-‐the-‐home socialisa;on Children can iden0fy with many social groups, and each group will have a different influence on their intelligence. 3. Transmission of culture via group processes Social norms learnt from the family are only kept and shared by the individual if they are accepted by the social groups they belong to. 4. Group processes that widen differences between social groups Social norms are not only formed from fidng in with a group, but from perceived differences of other groups whose features are rejected 5. Group processes that widen differences among individuals within the group The roles within a group will influence intelligence
Genetics Heritability of intelligence examines whether and to what extent intelligence is passed down through genes. • Children biologically inherit 50% of their
genes from the mother and 50% from the father during concep0on.
• Variability is the difference between a parent’s and child’s intelligence. It is assessed by looking at the propor0on of shared variance. High propor0ons (100%) suggests no variance between parent and child. This variance accounted for by gene0cs is the average es0mate.
• Does not mean that 50% of intelligence is inherited exactly from one parent, but popula0on-‐wise this is the case.
• Intelligence is suscep0ble to environmental influence as well, so an es0mate of heritability is calculated (h2).
• Three main types of studies are used to compare gene0c and environmental influences on intelligence: family studies, adop0on studies & twin studies
Education Stephen Ceci (1990, 1991) • Metaanalysis -‐ effects of a[endance on
intelligence test scores. • Overall finding were that children who
a[end school regularly scored higher on intelligence tests than those who a[ended less regularly.
• Intelligence test scores among pupils decreased over the long summer holidays.
• There was a rise of 2.7 IQ points for each year of schooling.
Douglas Wahlsten (1997) • Noted that studies have shown that delays
in star0ng school cause intelligence tests scores to drop by 5 IQ points a year.
Sorel Cahan and Nora Cohen (1989) • Length of schooling was important in
predic0ng performance, more than age, for all the verbal tests.
• Length of schooling also made a contribu0on, but a smaller contribu0on, to performance on nonverbal tests.
Within family factors
Reiss (1997) has implicated three main models to explain how the genes we inherit form behaviours based on the family environments: 1. The passive model: Intelligence is explained by an overlap in genes -‐ intelligence occurs because the parent and child share the same genes that influence intelligent behaviour. 2. The child-‐effects model: Parents react differently to children who demonstrate intellectual behaviours. Harris (1995) suggests that parental response can manifest in two ways: Posi;ve feedback loops (reinforcing the children’s natural intelligence) and Nega;ve Feedback loops (children prevented from behaving consistent with natural intelligence abili0es). 3. Parent-‐effects model: Parental response to the child influences the development of the child’s behaviour. The child’s intellectual behaviour is driven by their parent’s intellectual behaviour.
Twins
Due to a failed assassina0on a[empt on Nigel Powers, ‘Dougie’ was presumed to have died in a car explosion. He was then found and adopted by a ‘Belgium boulangerie worker and a fikeen year-‐old French pros0tute named Chloe who had webbed feet’.
Inherited 50% of genes from biological father and 50% from the biological mother. Iden0cal twins who are raised separately have a concordance rate of 76%.
Aus0n was raised by his father Nigel Powers. Nigel works as a spy for the Bri0sh Government and shares many similar personality traits. However, Aus0n felt that Nigel focused more on being a friend than a father-‐figure. As a result missed many important moments in Aus0n’s life ‘Daddy wasn’t there’.
• Student in the Bri0sh Intelligence Academy
• Winner of the Interna0onal Man of Mystery
• Interna0onal Super Spy
Nigel Powers is a Class I working professional (also a Bri0sh super spy). This meant he could afford to send Aus0n to the Bri0sh Intelligence Academy.
Aus0n remained in the care of his father and so is Bri0sh. Living in Britain during the ‘Swinging six0es’ caused his colourful dress-‐sense and dislike of authority figures such as Dr. Evil.
Dr. Evil was adopted by Belgians and this is accredited for his evil nature.
Dr. Evil’s adop0ve parents are Class V unskilled workers. Which meant that Dr. Evil should have been disadvantaged. However, Dr. Evil a[ended the same school as Aus0n, perhaps though scholarships.
• Top student in the Bri0sh Intelligence Academy
• Six years of Evil Medical School • Evil genius who has invented numerous
evil devices for either world destruc0on or domina0on
Inherited 50% of genes from biological father and 50% from the biological mother. Iden0cal twins who are raised separately have a concordance rate of 76%.
87% 86%
76%
55%47%
40%31%
24%
0% 0%0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Persontaking thesame IQtest twice
Identicaltwinsreared
together
Identicaltwins
rearedapart
Fraternaltwinsreared
together
Biologicalsiblingsreared
together
Parentsand
childrenliving
together
Parentsand
childrenliving apart
Biologicalsiblingsrearedapart
Adoptedchildrenliving
together
Unrelatedpeople
living apart
Level of genetic relatedness
IQ c
onco
rdan
ce r
ate
%
!
• People in Dr. Evil’s life that may have influenced his intelligence are: Number 2, Sco[ Evil, Frau Farbissina, Mini-‐me and Mustafa
• As leader of his evil organisa0on, the leadership role would have improved his intelligence. Although much of the technical running of the organisa0on is lek to Number 2.
• People in Aus0n’s life who may have influenced his intelligence are: Vanessa Kensington, Basil Exposi0on, Felicity Shagwell, Foxxy Cleopatra and Marie Kensington.
• Aus0n had a high role within the group, and at 0mes was required to take a leadership role, which would have increased his intelligence
Although having an extremely unusual upbringing, Dr. Evil parent’s seem to have encouraged his pursuit of evil. It is likely that posi0ve feedback loops and the s0mula0ng response of his parents developed his intelligence and evil disposi0on.
As Aus0n felt that his father was not fully engaged in his upbringing it is hard to tell what influence this had on his intelligence. It is possible he followed his father’s career path in an a[empt to gain recogni0on and respect.
