Sex Differences Flashcards
• To consider whether there are sex differences in intelligence. • To explore the potential biological and environmental factors that contribute to any sex differences in intelligence. To critically evaluate these explanations for sex differences in intelligence
when did interest in gender differences in abilities and behaviour start?
1880s
what did scientists believe about mental abilities and why?
men were superior in mental abilities because women’s brains were smaller
however, what did research across the 20th century suggest?
practically no difference
(Terman, 1916) Standford-Binet Test
- compared 1000 Cali School Children (4-16) -> compared boys and girls
girls had slightly higher scores
(Spearman, 1927) ‘g’
no sex difference
Cattell’s Fluid & Crystallised Intelligence
no difference in either
(Court, 1983) First systematic review considered 120, focusing on the abstract ability using the Raven’s Matrices
small differences but overall concluded no difference
what do systematic reviews use?
the narrative analysis approach
what is the narrative analysis approach?
- researchers weight up the evidence presented across a number of studies
- analysis only consists of assessing whether a study supports a hypothesis or not
- sample sizes vary across studies and these were usually opportune samples of less than 500
-> good first step but not as robust as other systematic can be
Lynn & Irwing (2004/5) set about conducting a more rigiorous view. What was this?
meta-analysis
why is a meta analysis useful?
- tend to overcome limit of a single study with limited sample sizes and instead they pull lots of different studies together and run additional analysis on them
- a meta-analysis uses results from numerous studies to calculate an average effect size
- potentially more meaningful as there’s a bigger same / range of participants
what is an effect size?
tells us how important a difference found between groups / conditions is
* we use Cohen’s d usually
Cohen’s d
0.2 (small effect size)
0.5 (medium)
0.8 (large)
Narrative Analysis
weights up findings across studies by analysing whether each studies findings support or don’t support a hypothesis
meta-analysis
pools together results from a number of carefully selected studies
-> additional analysis is run on this pooled data
Effect Size
tells us how important a difference is
Lynn and Irving’s findings -> pooled data from 87 studies = 80,000 participants
* positive effect sizes denote higher average among males compared to females and negative effect size denote a higher average among females compared to males
- in children (below 15), there was no difference (d = 0.02)
- 15-19, males scored 2 points higher (d = 0.16)
- undergrads, males scored 2-5 points higher (immediate effect size, d = 0.22-33)
- adults, men scored 5 points higher (immediate effect size, d = 0.30)
but is Lynn and Irving’s findings really the case?
Nyborg (2005) found:
small advantage for men
but is Lynn and Irving’s findings really the case?
Colom et al. (2000) and Spinath et al. (2008) found”
no difference
but is Lynn and Irving’s findings really the case?
Dykiert et al. (2008) and Hunt & Madhyasha (2008) found:
reported sex differences in intelligence tests could be explained by unrepresentative samples, rather than actual sex differences
-> could the 80,000 participants, be from the same background hence unrepresentative of everybody
but is Lynn and Irving’s findings really the case?
Hyde (2005) concluded:
males and females are more similar than different
what type of analysis pools the data from a number of studies to calculate average effect size?
meta-analysis
why doesn’t narrative analysis pull data from studies?
have a hypothesis but you look at each study in turn to see if the results support the hypothesis
what are two specific abilities of intelligence of interest?
spatial and verbal abilities
spatial abilities
- shape matching
- group rotation
- combining shapes
- cube views in 3D
- solids in 2D
- solids in 3D
- maps and plans
verbal abilities
- comprehension
- vocabulary
- spelling
- verbal reasoning
Maccoby & Jacklin (1974) compared these two specific intelligence abilities. What did they find?
- men perform better on tests of spatial abilities
- women perform better on tests of verbal ability
But do we still find sex differences when looking at it systematically? met analysis can give us a better idea
With Adolescents: Feingold (1988) and Hedges & Nowell (1995)
Across all ages: Linn & Peterson (1985), Hyde and Linn (1988), Voyer et al. (1995)
FOUND?
- some suggestions of women doing better in some verbal tasks than men (but small effect size)
BUT - tend of men doing better in maths and spatial ability tasks
- although there is a mix with some suggesting females doing better than males in verbal -> lot less robust and supported
spatial abilities: small-large effect sizes
verbal abilities: small effect sizes -> some larger in adolescence but small when combined
Benbow & Stanley (1983) noticed sex differences among 12-14 year olds who took the SATs early. What can we see in real world setting sex differences?
- no diff in group on verbal section
- diff in maths -> boys tend to do better
- twice as many boys than girls with meths scores higher than 500 (out of 800)
- 4x as many boys with scores of at least 600
- 13x as many boys with scores of at least 700
What did Blackburn (2004) find about the previous SAT research?
13:1 ratio for top achievers has reduced to 3:1 and remained that way since the early 1990s (Wai et al., 2010)
what is the summary of sex differences on intelligence?
- small effect size in favour of men in general IQ -> MIXED FINDINGS
- medium effect size for men in spatial intelligence
- small effect size in favour of men in mathematical ability
- no real robust evidence favouring women in verbal intelligence
there are 4 potential biological nature-based explanations to why sex differences in intelligence may exist. what are these?
- brain size / structure
- brain function
- hormones
- evolution
biological: brain size
- men’s brains are (on average) 10% larger than women’s -> difference only seen from adolescence onwards due to different rates of maturity
- link is small and has been overused as an planation
Pietschnig, Pinke, Wickerts pulled 8000 participants and they looked at the variation in intelligence scores in terms of sex variation and how much brain size contributed to that differences and variation. what did they find?
a different but it only explained such a small part of the large variance that the small role was not the main thing influencing any differences we see
* link is too small and overused as an explanation
Could differences in brain structure influence differences in intelligence?
- tasks are solved more efficiently when carried out by one side of the brain
- Allen et al. (1991) found females have bigger selenium and larger corpus coliseums (Steinmetz et al., 1995)
What does having a bigger splenium / corpus callous mean?
tasks are more evenly distributed between the hemispheres (Innocenti, 1994) -> idea that female brains are more bilaterally organised in their representation of cognitive function (more communication happening between the two hemispheres)
why may bilateralisation impact intelligence?
less lateralisation decreasing efficiency of tasks and that is what is contributing to the sex differences we see in general intelligence and maybe spatial mathematical ability
where is language usually lateralised?
left -> connection via corpus callosum
* aplenium is part of the corpus callosum
what is grey matter?
processes information in the brain
* the structure within grey matter (i.e. dendrites, soma) process signals generated in the sensory organs or other areas of grey matter and directs sensory stimuli to nerve cells
what is white matter?
transports the information
* information is encoded in action potential and propagated along neurones
* WM integrity determines the speed and fidelity of that information
Haier et al., (2005) used MRI to find areas of the brain relating to intelligence. What did they find?
IQ among females were related to more white matter areas and fewer grey matter areas than males
* males and women can achieve the same IQ scores with different parts of the brain
* intelligence in males might be more related to information processing (i.e. spatial ability)
‘males and women can achieve the same IQ scores with different parts of the brain; -> why might this be the case?
one sex may show better performance than the other depending on what the task is and what kind of information / processing it involves -> i.e. if we’re looking at differences in spatial ability which is more about information processing
* if men tend to solve/intelligence based on activation of grey matter in tasks such as spatial abilities which depend more on information processing, that is why they are showing better performance
Could differences in hormones account for sex differences in spatial ability?
Testosterone has been found to be related to high performance in spatial ability tasks
* reminder m and fs have testoterone and oestrogen but in lower levels compared to the opposite sex
testosterone
male sex hormone responsible for growth and development of male genitalian in womb and during adolescence
oestrogen
produced mostly by ovaries, responsible for female secondary sex characteristics
Choi & Silverman (1996) looked at how males and females provided directions
- participants given map of fictional towns icl compass and distance indicators
- asked to learn shortest route between two different points
- had to provide written directions and saliva samples were taken to measure hormone levels
- females gave relative direction and landmarks
- makes gave distance and cardinal directions -> tend to use compass as well (positively related to hormone)
- among males, testosterone was positively related to using distance and cardinal directions
testosterone has an effect on organisation of spatial skills
Barry et al. (2013) considered a 3D mental rotation task with females with polycystic ovary syndrome (elevated levels testosterone). what did they find?
PCOS participants scored significantly higher than controls on this task
* high levels of testosterone are impacting their performance
- sex differences we see in spatial abilities could be from hormone differences
why did men need spatial ability during evolution?
- hunting over large areas
- engaging in warfare with others
- maximising reproductive success
did women need spatial ability during evolution?
not as much because instead they
* gathered crops over small areas
* spatially restricted due to pregnancy or childcare
what does Jones et al (2003) suggest as an evolutionary explanation?
males with greater spatial ability are more likely to
* win wars
* supply food
* maintain relationships
* have attraction
* more offspring with ‘spatial ability genes’
however these arguments can be quite…
circulatory..
* did they have good spatial ability which made them good at hunting or did they need hunting which improved their spatial ability?
what are some issues with the evolutionary explanations
- ignore women have always needed to engage in spatial tasks
i.e. travelling long distances to find plants that ripen in different locations in different seasons - ignore ev that women played a significant role in hunting and warfare (Adler, 1993)
-> these explanations might be an evolutionary contribution to the sex differences we see but it’s not clear what it is yet -> there is a lack of robust evidence
But what happens when we control for nature?
Hoffman et al. (2012) examined spatial ability in two genetically related tribes but different environments -> if we accept only biological explanations, would expect in differences in spatial ability (similar genetic makeup but different environment and social structure)
- tested spatial ability in two different tribes who shared a genetic background, but women played a different role in society for each
(one matriarchal structured / other patriarchal)
male were significant faster than females when performing a puzzle task in the patriarchal group
BUT in the matriarchal group, there was no significant difference between sexes -> we do not see the same differences suggesting there are environmental impacts as well
what about looking at the impact of environment through stereotypes? what are some stereotypes?
- general
- preference
- toys
- culture
- education
- threat
- global inequality
what are some examples of stereotypes?
can be a central influence -> impact how we should behave and about how others should behaviour
i.e.
* boys tend to play with toys that encourage development of spatial awareness skills
* campbell et al (2000) toy preferences reflect gender stereotypes in children as young as 9 months old
Feng et al. (2007) looked at spatial attention and mental rotation among gamers / non-gamers and males / females
what did they find from experiment 1?
- games performed better than non-gamers (spent a lot of time playing games -> developing spatial navigation skills)
- no sex differences in gamers group (when someone has had more opportunities to develop these skills, no sex difference is found)
- males performed better than females (non-gamer group)
Feng et al. (2007) conducted a second experiment with non-gamers.
- experimental group: 10-hours action video game training
- control group: 10-hours non-action game training
What did they find?
- all those in E group improved in ability
- females benefitted more than males
- in E group, no sex difference after training
- in C group, males performed better both pre and post training
(if we see sex differences at the start and females are given the opportunity to develop these skills then the sex differences disappear)
Did the SAT in the USA gap close?
gap closing occurred during a trend in special programs and mentoring to encourage girls to take higher level maths and science courses (Snyder et al., 2009)
* to give them more opportunities to develop these skills, we see this gap close suggesting there’s some sort of role in environment here)
environmental stereotypes and preferences: reinforcement
Langlois & Down (1980) - mothers and fathers reinforce sex appropriate behaviour and discourage sex inappropriate behaviour
-> parents (outside sources) reinforce development which influence these stereotype preferences
environmental stereotypes and preferences: modelling
children observe same sex others and gain stereotypes on how they ‘should’ behaviour (e.g. what toys to play with) forming part of their gender identity
environmental stereotypes and preferences: socialisation of boys
Entwistle et al. (1994) -> boys are given greater freedom to explore, more opportunities to develop their spatial ability skills
what about stereotypical toys?
Seavy, Katz and Zalk (1975) -> participants chose toys associated with stereotypical view of gender
Sidorowicz & Lunney (1980) [playing with a baby, they gave the baby]
* if the baby was perceived a boy: 50% male & 80% females chose football
* if perceived a girl: 88.8% male & 72.7% female chose doll
what is the impact of stereotypes and toys?
girls are often made to engage in toys which don’t teach or offer them any spatial awareness or physical confidence
* men hugely dominant maths, spatial awareness and physical confidence
when children play spatial games frequently, their brains change physically within just three months
* inadvertly and unconscious, caregivers are influencing and guiding some of the toy preferences -> they are influencing it, yet adscripting that to the idea that they choose it themselves
what was a campaign to stop stereotypes?
let toys be toys
what about stereotypes across cultures?
there is a strong trend from late 90s research that looked at stereotypes across cultures, going across 25 different countries and asking them what characteristics that are commonly associated with men and women
they found men’s characteristics were more active (linkage to freedom) while women were more passive
Hyde et al. (1990) looked at a meta-analysis involving nearly 4 million participants. what did they find?
no gender diff in mathematical performance (d=-0.05)
* slight female advantage in computation (d= -.14)
* no difference in understanding of concepts (d = -0.03)
* no differences in complex problem solving (d = 0.08)
* but at high school d = 0.29 and college 0.32
a replication study about education in 1995
high school males performed better than females
* could be because of difference in course taking? (men took more maths / science courses and this is what is influencing the difference we’re seeing)
what about stereotypes in education when it comes to stem subjects?
girls less likely to choose these subjects as they are stereotyped as ‘masculine subjects’ -> therefore less likely to develop spatial skills
WISE (2014) report: 21% of Physics A Level entrants were female -> largely undertaken by men
Moss-Racusin et al. (2012) looked at applications for Lab managers in STEM subjects which were randomly given male or female names (the applications were identical)
faculty rated male applicants as more competent and hireable than females (despite the applications being identical)
* males were rated to be more competent at stem subject than females -> stereotype
negative stereotypes about different social groups can affect ability.
Spencer et al. (1999) formed 2 conditions:
1. males and females took a maths test
2. males and females took a maths test but told the males had score better on the task in the past
females in condition 2 scored lower than men
* but no diff found in condition 1
-> reminded women of stereotype, performing lower because that’s what’s expected of them
what about a situation of threat in the presence of others.
Inzlicht & Ben-Zee (2000): participants took maths and verbal tests which 2 conditions for each:
1 female participant with two other females (same sex)
2. female participant with two males (minority)
in verbal test, no diff in performance whether they were in either group
In Maths condition, better scoring when there were two other females than when in the minority
-> even presence of others can bring about this stereotype threat affect
what about the environmental inequality?
global gender gap by world economic forum suggests nations with greater gender equal portray smaller gender differences in mathematical performance
so how can we summarise sex differences?
there is definitely a role in environment when it comes to sex differences (variance within a population) but also biological (which may also further influence environment through an interaction effect and vice versa)
what are issues with the psychobiological / psychosocial model?
difficult to know whether biological differences influence sex differences and therefore stereotypes or whether stereotypes influence sex differences [interplay of biological and environmental approach)
Swim (1994)
found stereotypes can often reflect real differences in ability (accurate stereotypes) as well as biased differences (over or under emphasised stereotypes)
do learning experiences have an influence of brain development?
Yes - even during adolescence synaptic pruning occurs
* environment can influence brain development and vice versa
hormonal factors determine sex / aggression / temperament
parents may encourage certain activities based on these
* Even with hormonal factors which can influence strictures and biological impacts in the brain as well as influencing your environment
* But also others opinions of how other’s opinions of how hormones impact you during adolescence can feed into that
* Overemphasis of some ideas about hormones, which could feed into how caregivers react and deal with their adolescent children
* Hard to know what’s first and where things are starting
THEREFORE WE SHOULD CONSIDER BOTH (aka. psychobiological approach)
Do the two sexes use different strategies when we measure intelligence?
Olsen et al. (2013)
- mental rotation task given to both sexes
- given a small screen laptop and large display wall screen
what did they find?
- females performed faster than men in the large screen condition
- suggests that men solve mental rotation tasks using a ‘holistic’ strategy while women use a more ‘step-like’ strategy
what are some other potential issues?
what is intelligence always?
are we measuring it correctly?
focusing on the binary?
what about other types of intelligence?
BUT ALSO WE MUST REMEMBER NOT TO GENERALISE TOO MUCH BECAUSE THERE’S SO MANY SMART WOMEN OUT THERE
female mathematicians
* Marie-Sophie Germain (French, 1776-1831)
* Emmy Norther (German, 1882-1935)
* Maryam Mirzakhani (Professor at Standford)
Top scores at International Mathematical Olympiad
* difficult competition in mathematical solving
* top scores: exceptional (1-in-a-million level) skills
* An increase in the number of female participants with time
what are some biological explanations to gender differences?
- Brain
- Hormones
- Evolutionary
what are some environmental explanations to sex differences
- Stereotypes
- Socialisation of children
- Education
What are some psychobiological explanations of sex differences
- Stereotypes: accurate (biological)
- Biased (environment)
- Brain development (synapse pruning influenced by environment)
- Hormones: affect how children are treated
