Chapter 5 Flashcards
Identify genes hormones, as well as structure and function of the brain as the causes of observed differences in cognition, behavior, and even gender roles
Biology Theories of Sex
How has the contribution of genes to femininity and masculinity been examined?
By comparing monozygotic twins
What are Monozygotic Twins?
Identical twins sharing 100% of their genes
What are Dizygotic Twins?
Sharing 50% of their genes
What is the theory behind these twin studies?
Is that genes explain the greater similarity in behavior between identical twins compared to fraternal twins.
Study done by Iervolino et al. 2005:
examined 3-4 year old twins and the environmental contribution to sex-typed behavior
Results for the Iervolino et al. 2005 study showed
- There was a greater correspondence among monozygotic than dizygotic twins
- Greater correspondence between dizygotic twins than siblings
What did the results infer?
TF, inferring that both GENETICS and ENVIRONMENT made significant contributions to SEX-TYPED BEHAVIOR
What was the difference in the Iervolino et al. 2005 study when it came to sex?
The genetic contribution was stronger for girls than for boys
Knofo, Iervolino, Plomin (2005) study used same twins; what was the purpose of this study?
To determine the genetic and environmental contribution to GENDER ATYPICAL BEHAVIOR
The results of the Knofo, Iervolino, and Plomin (2005) study?
Genes were said to acct for a moderate amount of variability but ENVIRONMENT was said to account for a SUBSTANTIAL PORTION of variability
What was the genetic component stronger for, boys or girls?
Girls
Besides examining the contribution of genetics and environment to sex-typed behavior, twin studies have also examined?
Heritability of homosexuality
Heritability of homosexuality shows that:
it is higher among monozygotic twins than in dizygotic twins
20%-24% compared to 10% or less
What are the chances that both monozygotic twins turn up homosexual?
far from 100%
A question that we should raise is:
whether the environment for the identical twins is really the same as the environment for fraternal twins.
What is a social behavior for which there are clear cut sex differences when it comes to twin studies? Where is the correlation?
Aggression; there is a correlation b/w monozygotic twins than dizygotic twins when it comes to aggressive behavior
A meta-analysis of 51 twin and adoption studies showed:
genetics accounted for 40% of antisocial behavior
What are adoption studies used for?
They are used to est. the contribution of genes to behavior
What do adoption studies compare in order to show the contribution of genes to behavior?
they compare the similarities in behavior between adopted siblings
to the similarities in behavior between
biological siblings
who have been reared apart
Sex-related chromosomal abnormalities also have been linked to?
Aggression
Some studies have shown a configuration among men in prison, what is this configuration?
Higher than avg. proportion of men with XYY configuration (extra Y chromosome)
Is the configuration of the extra Y chromosome in prisoners TF state that all men with the extra Y chromosomes are in fact prisoners?
no, the vast majority of men with the extra Y chromosomes are not prisoners
Boys w/XYY pattern:
are more irritable and have more temper tantrums than boys that do not have this configuration
What are HORMONES?
These are chemicals produced by the endrocine system that circulate throughout the body
What are the 2 classes of sex-related hormones?
Estrogens
Androgens
What are ESTROGENS?
female sex hormones
What are ANDROGENS?
male sex hormones
Does this mean that only women have estrogens and men only have androgens? If not then what does this mean?
No, it means that females and males have a different amount of estrogens and androgens
What do sex hormones effect?
Brain
Immune System
Overall health
Influence Behavior
An avenue of research that has enabled us to study the effects of hormones on behavior:
Intersex condition
What is INTERSEX CONDITION?
there is some inconsistency between the individual’s chromosomal sex and phenotypical sex
Congential Adrenal Hyperplasia (CAH)
a genetic disorder resulting in a malfunction in the adrenal gland that results into prenatal exposure to high levels of male hormones and lack of cortisol
Girls with CAH may be:
Do boys have any adverse effects?
Girls: may be mistaken for boys their genitals are somewhat masculinized
Boys: do not have any adverse effects
Consequences to CAH: cognition= (girls and boys)
Girls w/CAH have superior spatial skill
Boys w/CAH have inferior spatial skills
Puts et al. 2008
show that there is a curvilinear relation b/w androgens and spatial abilities
Consequences to CAH: Brain Structure= (girls)
Ernst et al. 2007 amygdala activation in CAH females was stronger than females with non-CAH similar to to that among males
Ernst et al. 2007 study:
Brain activation in response to facial emotions
Consequences to CAH: Hormones (girls and boys)
Paterski et al. 2007
compared 3-11 YOA girls and boys to their unaffected siblings
Paterski et al. 2007 study results show?
CAH girls:
Behavior: more active and aggressive than non CAH girls
Play Behavior: played with boy toys rather than girl toys
CAH boys: no difference in Behavior of play behavior
Do exposure to prenatal androgens lead to sexual orientation and identity problems?
No, Majority of CAH females are heterosexual
Deeseens, Slijper, Drop 2005 study:
280 individuals w/CAH reared as females
Results: 13 gender identity prob. and 4 wished to be male
3 Potential Explanations for the link of CAH to spatial skills
- Androgens could affect areas of the brain that are linked to spatial skills, masculine social behavior and sexual orientation
- Androgens could effect the tendency to engage in activities that affect cognition and behavior
- The masculinization of appearance could somehow influence behavior
Sidebare: Does test. cause aggression
there was a weak positive relation of test. to aggression (d=+.28)
What happens to males test with age?
Males test. decreases with age
For males 13-20 YOA what was there most aggressive behavior observed by?
high test. and low cortisol
Is there a correlation between aggression and test.?
yes and therefore no causation