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Lecture 4

1. General intelligence

   • Effect sizes
     • Show how important the difference is
       • 0.2 = small
       • 0.8 = large
   • Lynn & Irwing (2004/5)
     • No sex differences <15 (d=0.02)
     • Men scored 2 pts higher 12-19 years (d=0.16)
     • Men scored 3-5 pts higher undergrads (d=0.22)
     • Adults scored 5 pts higher (d=0.30)

2. Spatial Ability

   • Medium effect size in favour of men
     • Linn & Peterson (1985)
     • d=0.51

3. Mathematical Ability

   • Small effect size in favour of men
     • Else-Quest (2010)
     • d=0.11
   • Ellis (1984)
     • Proposed there is more variability of intellectual abilities among males
       • Greater Male Variability
         • Fewer female geniuses
   • Penner
     • GMV is not universal
       • Must be due to socio-cultural factors

4. Verbal ability

   • Virtually no effect size
     • In favour of women

5. Biological Explanations

   • Brain size
     • Splenium larger in females
       • Allen (1991)
       • Increased connectivity/even functioning
         • Tasks more efficient carried out on one side
   • IQ related to more white-matter in females
     • Haier (2005)
       • White matter involved in information transmission
       • Intelligence in men may be more related to information processing
         • Gray matter involved in information processing
     • Types of matter influences scores
       • Due to how information is processing
   • Evolutionary
     • Men needed spatial ability when e.g. foraging and engaging in warfare
       • Jones (2003)
         • Males with greater spatial ability were able to pass on those genes
           • Survival of the fittest argument
         • Circular theory?
   • Hormones
     • Testosterone and Oestrogen
       • Testosterone found to be related to higher performance on spatial ability tasks
         • Choi & Silverman (1996)
           • Women provide relative directions and landmarks
             • Men provide distance and cardinal direction
               • Testosterone positively related to these directions
         • Barry et al (2003)
           • Women with polycystic ovary syndrome
             • Elevated levels of testosterone
               • Scored higher on 3D mental rotation tasks
   • BUT
     • Lack of cross-culture consistency
       • Hoffman (2011)
         • Patrilineal tribes: men outperformed women
         • Both scored evenly in matrilineal tribes
           • Shared genetic background: Environmental impact on development of spatial abilities

6. Environmental Explanations

   • Stereotypes
     • About how we/others should behave
     • Boys tend to play with toys that encourage spatial awareness
       • Show preference for gender stereotype toys as young as 9 months
         • Campbell (2000)
       • Feng (2007)
         • Male non-gamers perform better than females
           • Training reduces sex differences
         • No sex difference for gamers
   • Preferences arise from:
     • Modelling
       • Children observe same sex others
     • Reinforcement
       • Langlois & Down (1980)
         • Parents reinforce sex appropriate behaviours
   • Stereotypes in educations
     • Hyde (1990)
       • No gender differences in mathematics
         • Replicate study (1995) showed high school boys perform better
           • Influence of educations
     • Girls less likely to choose STEM subjects
       • Seen as masculine
       • Moss-Racusin (2012)
         • Rate male applications as more competent for STEM subjects
           • Despite female applications being the same
     • Stereotype threat
       • Negative stereotypes affect ability
         • Spencer (1999)
           • When told males score higher on a test
         • Inzlicht (2000)
           • When in the presence of males

7. Psychobiological Model

   • Both factors have an impact
     • Swim (1994)
       • Stereotypes reflect 'real' differences in ability
     • Learning experiences influence brain development