Gender Differences in Cognitive Ability

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Gender Differences in Cognitive Ability

• Dr. Jenny Wilson

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What is meant by Gender Sex?

• Sex refers to physiological traits
• Whereas Gender refers to psycho-social states.
• However, research literature shows definitions
  inconsistent (Weiman, 2001)
• We will use both terms interchangeably for this
  lecture

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What do we mean by cognitive ability?

• The term cognition (cognoscere, "to know") refers
  to the way we think about or process information.
• Example of such cognitive processes include
  memory, attention, perception, problem solving
  and mental imagery and language.
• Cognitive ability therefore can be defined as our
  performance on cognitive tests.

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Do differences exist?

• Jurys still out..
• A great deal of research has identified
  differences between the sexes in some areas.
• In particular men excel on spatial tasks whereas
  women excel on tasks of verbal fluency.
• BUT recent meta-analysis has shown no differences
  in cognitive ability, or where differences do
  lie, a small effect size.
• So depends where you look.

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Sex differences Spatial Ability

• One of the most popular tasks to use in measuring
  individual differences in spatial ability is a
  mental rotation task introduced by Shepard and
  Metzler (1971).
• In the mental rotation task, participants make
  judgments about 3-D objects
• The participant's task is to determine as rapidly
  as possible which the figures is the same (i.e.
  differs only in rotation angle)
• Men on average are better at this kind of mental
  rotation task, which involves maintaining and
  manipulating a visual image in working memory
  (Halpern, 2000).

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Example of mental rotation test
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Have a go
See task 1 on your handout
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Sex differences spatial ability

• Men also perform better on visual-spatial ability
  tests of aiming at and hitting a target. (Moving
  and stationary targets)
• As well as throwing and intercepting projectiles
  (Kimura, 1992)
• Women perform better on tests of manual dexterity

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Sex differences spatial ability

• Men tend to perform better than and differently
  from women at navigation. (Voyer, et al.1995)
• Males use distance, direction geometric shapes
  for navigating a route
• Women rely on landmarks (Saucier 2002)
• Male superiority in spatial ability found in
  other species.

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Object location

• View for 15 seconds
• You will be shown the picture again, but
  object(s) will have moved.

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Memory for Object location

• What moved?

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Look again.

• Possibly because women use landmarks as
  navigation, they excel in tasks of memory for
  object location

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Sex differences and visual tasks

• Women outperform men on tests of perceptual
  speed.
• Perceptual Speed is the ability to quickly and
  accurately compare letters, numbers, objects,
  pictures, or patterns. (see task 2)
• The things to be compared may be presented at the
  same time or one after the other.
• This ability also includes comparing a presented
  object with a remembered object.
• However, on the complex figures task males
  outperform women. http//www.exn.ca/brain/tests/

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Gender Differences Verbal ability Fact
Fiction

• It was widely believed that women had superior
  language ability.
• Girls do show an advantage for verbal abilities
  (on average) female infants demonstrate an
  earlier onset of fluent speech and have longer
  Mean Utterance Lengths than boys.
• Girls also develop the use of passive voice and
  other complex grammatical construction earlier
  than boys (Kruger, 2001)
• In adults reliable differences have not been
  found in vocabulary or verbal reasoning. HOWEVER
  women do seem to excel in tests of verbal memory
  verbal fluency.

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Gender differences and verbal Ability

• Verbal memory taps into the recall of verbal
  material. For example, words in paragraphs,
  lists, abstract or concrete words.
• Verbal fluency is the ease in which an individual
  can produce words. It requires the generation of
  words constrained in some way.
• E.g. Generating lists of words beginning with
  same letter.
• Or Association fluency generating synonyms
  (Halpern, 2000 Kimura,1992)

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fluency test

• Name as many words beginning with the letter C as
  you can. You have one minute.

• Name as many words meaning happy as you can.
  You have one seconds

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Differences

• The evidence seems to suggest that differences on
  some aspects of cognitive ability do exist.
• However, it should be considered that there is
  much overlap in the abilities of males and
  females.
• Further, there is much variability within gender
  groups particularly for males.
• Males are more likely to be represented at both
  tail-ends of normal distribution.

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Differences

• One the one hand, there are higher percentages of
  males identified as having learning disabilities
  (Dyslexia, dysfluency, delayed speech, ADHD)
• But on other hand higher frequency of
  giftedness in males (particularly mathematics
  and science)
• Pennington (1991) argues undercounting accounts
  for lower numbers of females with dyslexia and
  giftedness.

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Differences

• Recent studies using the technique of meta
  analysis (Hyde, 1990, 2005) concluded although
  some differences do exist, males and females more
  similar than different.
• Meta analysis is a statistical method for
  aggregating research findings across many
  studies.
• Effect sizes are then examined.
• 'Effect size' is a way of quantifying the size of
  the difference between two groups.
• Concluded 78 of gender differences reported were
  small or close to zero.
• This is areas where gender differences thought to
  be reliable (e.g. verbal ability)
• Based on these findings proposed gender
  similarity hypothesis

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Why might there be differences?

• We have established that, although smaller than
  often portrayed, differences do exist on certain
  aspects of cognitive ability.
• The next question we will consider is how this
  might be explained.
• Biological/Physiological
• Evolutionary theory
• Social
• this lecture will consider the first two
  explanations

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Biological Explanations

• Neuroanatomic differences
• Brain size
• Male brain approx 10 larger than female brain.
• BUT after adjustment for body-size the
  body-weight ratio for female brain actually
  larger.
• Female brain contains more grey matter
  (implicated with processing)
• Male brain more white matter (transfer
  information among different brain regions)

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Neuroanatomical differences

• Cerebral hemispheres in males are asymmetric.
• Right cerebral hemisphere larger.
• Possibly implicated in superior spatial ability
  though findings inconclusive
• Females more symmetrical, or bilateral with both
  functioning equally in processing of speech?

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Neuroanatomical differences

• Corpus callosum, a major neural system connecting
  the two hemispheres, is larger in female brain
  (Holloway de Lacoste, 1986)
• However, findings not consistent.

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Hormones and Cognitive differences

• TESTOSTERONE LEVELS can affect performance on
  some tests.
• Women with high levels of testosterone perform
  better on spatial tasks than women with low
  levels.
• BUT men with low levels outperform men with high
  levels.
• Suggest optimum level
• On a test of perceptual speed in which women
  usually excel, no relation was found between
  testosterone and performance.

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Testosterone cognitive ability
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Evidence for effect of Testosterone

• Congenital adrenal hyperplasia (CAH)
• CAH is a genetic defect of the adrenal glands. A
  person with CAH will not be able to produce
  several vital hormones known as corticosteriods.
• In some cases there is an over production of the
  androgens (male hormones).
• Girls with CAH demonstrate better spatial ability
  than unaffected girls.
• Boys affected by CAH have reduced spatial ability
  relative to unaffected boys.
• Hypogonadal Males (e.g. Kallmanns syndrome) who
  have lower levels of testosterone also
  demonstrate poorer levels of spatial ability than
  normal males.
• These cases provides evidence for an optimal
  level of androgens for the expression of spatial
  ability.

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Fluctuations on Sex hormones cognitive ability

• Estrogen/Oestrogen
• Primary Female sex hormone.
• Natural fluctuations occur during menstrual cycle
  (peaks mid-cycle)
• Does this affect cognitive ability?
• Interaction effect Negative correlation for
  spatial ability positive correlation fluency

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Fluctuations on Sex hormones cognitive ability

• Testosterone
• Primary male sex hormone.
• Natural fluctuations occur during seasons ( In
  Northern Hemisphere, higher in Autumn)
• Diurnal fluctuations (peak in morning) Does this
  affect cognitive ability?
• Not all aspects! Throwing math unaffected.
• Spatial ability measuring via mental rotation
  task better in SPRING (lower T-levels) compared
  to Autumn.
• Performance poorer in morning.
• CAVEAT!! Effect sizes very small!!
• Also Correlational data correlation does not
  imply causation!

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Hormones Cognitive Ability

• Evidence does appear to suggest that androgens
  (e.g. testosterone) do influence certain
  cognitive abilities, at least for certain spatial
  tasks.
• At the same time, it appears (high levels of)
  estrogens also have a negative impact on spatial
  tasks.
• However, the relationship is not straightforward,
  and certainly does not affect all aspects of
  cognition.
• It would appear further investigation needs to be
  undertaken before firm conclusions about the
  influence of hormones on cognitive ability can be
  drawn.

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Evolutionary explanations

• One explanation for the differences is
  evolutionary theory.
• Evolutionary theorists claim differences in
  cognitive ability between the sexes is due to our
  evolutionary history as hunter-gathers.
• During this time males females adopted separate
  but complementary skills for survival.

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Divisions of labour

• Men were responsible for hunting and navigating
  unfamiliar terrain.
• Women were involved in child care and foraging
  for food close to home.
• These specialist roles led to the development
  of cognitive abilities in their respective areas.

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Evolutionary theory as an explanation for
targeting ability

• Since males were largely responsible for defence
  and hunting the theory proposes that they
  subsequently developed skills that would aid
  these roles. Eventually these motor skills
  evolved into superior targeting ability. (see
  Sherry Hampson for review)

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Evolutionary theory as an explanation for spatial
ability

• Men were responsible for hunting, which may have
  involved traversing a greater distance.
• It is also assumed that males reproductive
  strategy was to mate with as many females as
  possible. Accordingly males would occupy a larger
  territory, and also need to develop shortcuts to
  traverse terrain. As a result spatial rules based
  on geometry and navigation skills evolved.

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Evolutionary theory as an explanation for
location memory

• In contrast women would forage near home for
  food. As a result navigation skills based upon
  memory for landmarks evolved.
• Women would also forage in the same area for
  perennial crops, so would need to recall the
  location relative to the home.
• Females are also more sensitive to touch, odours,
  taste and sounds.

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Evolutionary theory conclusion

• Evolutionary theory appears to offer several
  plausible explanations for the differences in
  cognitive ability between males and females.
• However, evolutionary theory is obviously
  difficult to test empirically, and the lack of
  consistent differences between males and females,
  coupled with the within sex variability in
  performance does suggest that evolutionary theory
  may be overstating its case.