TBCE Lecture 2

Topics in biological and cultural evolution: 

Topics in biological and cultural evolution Lecture Two Cognitive Sex Differences

Slide2: 

Recap on Lecture One: 

Recap on Lecture One Evolutionary psychology: A united field? Buss’s hierarchy of levels – emphasis very much on gender difference and gender conflicts Empirical work in evolutionary psychology

SEX DIFFERENCES? OrGENDER DIFFERENCES?: 

SEX DIFFERENCES? Or GENDER DIFFERENCES? Sex – aspects of the female/male difference that pertain to reproductive functions or that are likely to be linked to genetic factors Gender - social or psychological aspects of being seen as a man or woman or regarding oneself to be so.

It’s difficult to decide!: 

It’s difficult to decide! Halpern 2000 uses the term sex to refer to both biological and psychosocial aspects of the differences between men and women because these two aspects of human existence are so closely coupled in our society. It is frequently difficult to decide if the differences that are found are due to biological (sex) differences or psychosocial concomitants (gender) of biological sex

Sex differences?: 

Sex differences? Maccoby and Jacklin (1974) The Psychology of Sex Differences They dealt with sex differences in terms of their association with socialisation practices. Are men smarter than women? The answer to the above burning question is: No, they are not. There is data now being laid on the table that show that, on average, men and women are equal in mental ability. (Seligman, 1998)

Brain Size: 

Brain Size The assumption that ‘bigger is better’ as it applies to individuals of the same species has not survived the test of scientific examination … It may even be the case that paradoxically, less is better (Smock, 1999) Brain size and weight are positively correlated with body size

Slide8: 

Summary of theories of sex differences in the organisation and structure of the brain

Sex differences in lateralisation: 

Sex differences in lateralisation These are a class of theories that suggest that: Female brains are more symmetrically organised for cognitive functions Cognitive crowding hypothesis - female brains more likely to have verbal ability represented in both hemispheres Prenatal and perinatal hormones may cause sex differences in lateralisation – high levels in males cause slow neuronal growth in left hemisphere Possible conclusion – female brains are more bilaterally organised and male brains are more lateralized for cognitive tasks

Intrahemispheric Sex Differences: 

Intrahemispheric Sex Differences Sex differences in the organisation of cognitive abilities within each hemisphere have been proposed Functions are more focally organised in female brains and more diffusely organised in male brains

Size of Corpus Callosum: 

Size of Corpus Callosum It has been suggested that this thick band of neural fibres that connect the right and left hemispheres are the site of sex differences The posterior part of the corpus callosum is larger and more bulbous in shape in human females – prenatal and perinatal androgen and ovarian hormones seem to determine size of CC. This is consistent with the conclusion that female brains are better organised for the use of both hemispheres in cognition

Cognitive Crowding Hypothesis: 

Cognitive Crowding Hypothesis Women (in general) and left-handers (especially males) have better verbal skills because language is bilaterally organised. They also have poorer spatial skills because spatial ability is ‘crowded out’ due to the fact that spatial abilities share the neural architecture in the right hemisphere with the neural substrate for verbal abilities

Handedness and sex differences: 

Handedness and sex differences Predictions - Left-handed males have cognitive patterns similar to that of women (verbal skills better than spatial abilities) Are there differences between men and women in terms of verbal and spatial ability?

Verbal Abilities: 

Verbal Abilities Maccoby and Jacklin (1974) using evidence from 2000 studies concluded that there was no support for gender differences apart from psychological areas – verbal ability – female superiority, maths and spatial ability – male superiority – and the greater aggressiveness of males

Verbal Abilities: 

Verbal Abilities 1988 Meta-analysis of 165 verbal ability studies (1.4 million people) – on average females did score higher than males but the difference is tiny ‘I would argue, therefore, that there are no longer any gender differences in verbal ability’ (Hyde, 1996)

TESTS OF VERBAL ABILITIES: 

TESTS OF VERBAL ABILITIES

WRITING PROFICIENCY: 

WRITING PROFICIENCY

MATHEMATICAL ABILITIES: 

MATHEMATICAL ABILITIES Maccoby and Jacklin (1974) concluded that boys are better than girls at maths 254 samples (over 3 million subjects) However Hyde (1996) argues that overall girls actually outperform boys slightly Using meta-analyses Hyde also showed that the magnitude in gender difference in math ability has dropped by a half in the two decades between 1974 and 1996

MATHEMATICAL ABILITIES: 

MATHEMATICAL ABILITIES Geary (1996) Sexual Selection and Sex Differences in Mathematical Abilities Primary mathematical abilities – counting and understanding basic concepts in comparing quantities – no sex differences (PMA was found across cultures and developed universally in children’s play)

MATHEMATICAL ABILITIES: 

MATHEMATICAL ABILITIES Secondary mathematical abilities – solving mathematical word problems and geometry – sex differences in spatial cognition could be the underlying factor in explaining sex differences found in some types of math problems However there are many criticisms of Geary’s theory

MATHEMATICAL ABILITIES: 

MATHEMATICAL ABILITIES Overlap in maths ability cannot be explained with this theory (Casey, 1996) Relationship between spatial abilities and maths problem solving is tenuous (Dowker, 1996)

MATHEMATICAL ABILITIES: 

MATHEMATICAL ABILITIES Both sexes are equally responsive to education and training (Baenninger and Newcombe, 1996) Some sex differences are found prior to formal schooling and on supposedly biologically primary tasks (Stanley and Strumf, 1996)

SPATIAL ABILITIES: 

SPATIAL ABILITIES Sex Differences in Spatial Abilities: Evolutionary Theory and Data (Silverman and Eals, 1992) ‘The near universality of sex differences in spatial abilities across human cultures and their occurrence in other species indicate the feasibility of an evolutionary approach’

Slide24: 

SPATIAL ABILITIES: 

SPATIAL ABILITIES Sexual division of labour between hunting and gathering during hominid evolution Male Spatial Specialisation –Mental rotation tasks that usually show male bias Female Spatial Specialisation – Object and location memory showing female bias

Critiques of Silverman & Eals: 

Critiques of Silverman andamp; Eals Spatial skills were also needed for gatherers who often had to travel long distances to gather food (Halpern, 2000) There were many hunter-gatherer societies in which women hunted (Halpern, 2000)

Critiques of Silverman et al. or absence of discussion……..: 

Critiques of Silverman et al. or absence of discussion…….. Evolutionary driven hypotheses are not mentioned in ‘Gender Differences in Human Cognition’ Caplan, Crawford, Shibley Hyde, and Richardson, 1996) Where are the gender differences? Where are the gender similarities? (Hyde, 1996 in Sex, Power and Conflict: Evolutionary and Feminist Perspectives Edited by Buss and Malamuth)

Task: 

Task Look at the stimulus array for one minute

Slide29: 

Autism – 3 categories of symptoms: 

Autism – 3 categories of symptoms Impairment of social relationships – lack of eye contact and poor facial recognition Impairment in communication skills – problems in maintaining a conversation and understanding of metaphor Repetitious and stereotypical patterns of behaviour – obsession with routine, inability to cope with change

Theory of mind: 

Theory of mind A system existing in the brains of normal humans for inferring the mental states of others (Leslie, 1987) Sally and Ann false belief task (Baron-Cohen et al, 1985) To succeed in this task children have to realise that Sally can falsely believe that the marble is somewhere other than where it is

Simple false belief task: 

Simple false belief task Smarties and pencils example A child is shown that a smarties tube contains pencils. The tube is sealed again. The child is then asked what an observer would think was in the tube. Children under 4 years and autistic children usually answer pencils

Theory of mind, autism and the hyper-systemizing brain : 

Theory of mind, autism and the hyper-systemizing brain Humans have two ways of predicting the outcome of changing events (Baron-Cohen, 2006) Male infants learn about objects and their mechanical relationships. The cognitive apparatus seeks patterns and law-like behaviour – the systemizing approach Female infants learn about people, emotions, and personal relationships (Baron-Cohen, 2003)

Sex differences for intrinsic aptitude for mathematics and science: 

Sex differences for intrinsic aptitude for mathematics and science Baron-Cohen suggests that differences between male and female cognitive styles result from differing genetic influences on the systematizing ability Criticism – Spelke (2005) found that infants show few cognitive sex differences and no male advantage in the processing of objects, space, or number Older literature suggests that male and female infants are equally interested in people and objects (Maccoby and Jacklin, 1974)

The Gender Similarities Hypothesis (Hyde 2005): 

The Gender Similarities Hypothesis (Hyde 2005) Differences model dominates the popular media Gender similarities hypothesis suggests that males and females are similar on most, but not all, psychological variables Gender differences can vary substantially in magnitude at different ages and depend on the context in which measurement occurs