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