Does the brain have a gender? | Franck Ramus | TEDxClermont

This talk was given at a local TEDx event, produced independently of the TED Conferences.

Do men come from Mars and women from Venus? Are there actual differences in cognitive and brain function between genders? If there are, what are they and where do they come from? Education? Social conditioning? Hormones? Genes? Science provides a great deal of factual data allowing to take up these questions without getting trapped by stereotypes and ideologies.

Franck is the research director at CNRS (National Centre for Scientific Research) and a psychology professor at the department of cognitive studies at the École Normale Supérieure de Paris. His research focuses on children's language acquisition and their handicaps (dyslexia, language disorder, autism).

Are there cognitive differences
between genders?

I've got to be crazy

for choosing to broach
such a controversial topic to you!

Yet, there are good reasons to do it,
and you're well aware of them.

These are the statistics you all know.

For example: women are more often
in search of employment than men,

that they are paid less than men
in equivalent positions,

that they access executive
and managing positions

less often than men,

even when they are
just as qualified as men,

or even more, on average.

And so, these statistics are actually
appalling and I suppose that you all,

like me, would like to step
these numbers up to 50%.

However, various approaches differ

on how to achieve this goal.

If you have followed the debates
on this subject in the media recently,

even just a little, you must have noticed
that the main leitmotiv

which keeps coming up
consists of simply denying

that cognitive or cerebral differences
exist between genders.

Or, if they do exist,
that they are completely marginal,

or they are the result of stereotypes,
or educational biases

between boys and girls.

Well, personally, I find
this approach particularly bold,

since it makes a moral principle
rest on facts which can or cannot

be observed in real life.

So, imagine that tomorrow,
a new scientific research is published

and clearly shows that there are
cognitive differences between genders,

then everything collapses
and all of a sudden,

people will tell themselves,

"Actually, there were differences.

I was right to discriminate women
in hiring and to pay them less than men."

We can see that there is something wrong
about these arguments.

Even more so, given that these arguments
have already been proven wrong

since proofs of cognitive differences
between genders actually exist.

This is what we're going to do today.

For the first time, go over the data
which actually shows

this is in fact, the case.

Then, come back to our initial question.

Thus, there are cognitive differences
between genders, but which ones?

All those which we are talking about
aren't necessarily real.

For example, in the 19th century,
we believed that women

were less intelligent than men, as said
by the famous neurologist, Paul Broca,

perhaps due to the smaller
size of their brain.

Facing such an assertion,
there are two possible stances.

You can either say that it's absolutely
unacceptable, so it has to be false,

but you will concede
that it is some sort of wishful thinking.

Or you might take a more scientific
approach, and check the data.

Let's see if it backs up this hypothesis.

If we take a look at the data,

first: do genders have
a different brain volume?

Yes, they do: men have a brain
that is, on average,

9% larger than a woman's.

Second question: is it true
that there is a link between brain volume

and general intelligence,

which we can measure through IQ tests?

The response is once again yes,

which you see illustrated
by these lines here.

The differences in brain volume
between people explain

around 10% of IQ differences.

Third point: does that mean
that women necessarily have

a lower IQ than men?

By looking at the data,
we can respond to this question.

Here is the data from a particular study

that was confirmed by many others.

You see people's brain volume
on the x-axis,

and on the y-axis, their IQ.

The men are in black
and the women in white.

What you see, if you look
at the x-axis, is effectively

that the men have larger brains
than the women.

If you look at the lines that show
the connection between brain size and IQ,

you clearly see that within the men,
there is a relationship,

and within the women,
there is also a relationship.

Look now at the IQ on the y-axis,
you see that, on average,

there isn't an IQ difference
between women and men.

From a scientific approach,
this allows to give

a firm and definitive response
to Broca, which is: no.

Men and women do not differ
in terms of general intelligence.

Well, does that mean
that there is no difference?

Not necessarily.

There could be more subtle differences.

For example, on the brain level,
if you look at different brain regions,

there are some that differ
between men and women.

This image shows that the regions in blue
have larger volumes of grey matter

in men than in women, on average,

while the red areas have
larger volumes of grey matter

in women than in men.

I will not go through
all of the regions in detail,

but some are in the limbic system,

also known as the emotional brain.

If we look at it on a cognitive level,
is it manifested through differences

of performance during tests?

Once again, the response is yes.

There is a handful of cognitive
functions where men and women

differ a little.

You see an illustration here.

These are two cognitive tests.

The first, which we see on top,
is a kind of Spot the Difference.

You've got a board
with a certain number of objects.

You look at it, then it's hidden,
and the second board is shown to you,

and you have to guess
which items changed place.

It's a task of spatial
locations memorisation.

The task below:
you are shown a 3D object

and then, you are shown several others
that are the same object

which has been rotated,
but one amongst them shouldn't be there,

as it is not the same object rotated,
but its mirror image.

You are asked to find this one.

One of these tasks is better
performed by men,

while the other is better
performed by women.

Are you able to guess which is which?

We are going to test you.

You will vote by raising your hands.

Those who think
that the spatial location task

is better performed by men,

and the mental rotation task

is better performed by women,
raise your hands.

Go ahead, I want to see your hands.
There isn't a lot of you.

Are you guys shy?

The people who think exactly
the opposite, raise your hands.

Straightaway, there are more hands.

And so I can tell you
that the majority of you, indeed,

have the right intuition.

Meaning that women are better
at memorisation tasks

of object locations, while men are,

on average, better at tasks

where you have to manipulate
objects in space.

It's not enough to show that men and women
differ on such and such test.

Because, what does that prove?

It doesn't prove the difference is innate.

There are many factors that lead
to such performance differences.

Perhaps it's education:
it's a fact that boys are not educated

in the same way that girls are,

that girls are not encouraged
in the same activities,

they are not led to the same things.

There can also be stereotype biases.

I will illustrate this stereotypical bias

through this famous American study
in which they gave

a quite complex math test
to university students.

The first version had a notice explaining

that it was a math test in which men

usually performed better than women.

The observed results did indeed
conform to this suggestion,

namely that men have
better results than women.

In a second version, they gave exactly
the same math test,

but only changed the instructions

which said, "Here is a math test in which
there is no difference between genders."

And there,

the results showed
no difference between genders.

Thus, you see that, eventually, through
a simple suggestion, you can induce

stereotypes in people's minds
that they will end up conforming to.

It's a bit like
a self-fulfilling prophecy.

We think, "Of course,
these kinds of stereotypes,

there are many of those, especially
stereotypes devaluing women."

Then, if women internalize it
and conform to this stereotype,

then that could explain the numerous
differences observed.

To be sure, once again,
it's necessary to examine the data.

Here is a long list of tests,
in which we compared

men's and women's performances.

The ones that do not differ between men
and women are those on the middle line.

Those with the pink lines
going to the left

are the tests
that are to the women's advantage.

Those with the blue lines
going to the right are the tests

that are to the men's advantage.

The length of the lines reflects the size
of the difference between genders,

on a statistical level
which I won't explain to you.

But in order to fix ideas, look
at the blue line at the bottom.

It's the size of the difference
in body size between the sexes.

Men are, on average,
a little larger than women.

This is irrefutable!

And this difference has a size that is two

on this statistical scale,
what is represented here.

In comparison, the majority
of cognitive differences

between genders is not actually that big.

They are lower than 1 on this scale,

so by taking a man and a woman randomly

and by comparing them on these tests,

they have less chances
of being different than if we took

two men randomly or two women randomly.

Let's say they are lesser differences.

Could they be completely explained

by stereotype biases?

You have to compare them
to the effects of stereotype

represented by the grey area.

Effectively, you see
that a certain number of these differences

in the middle, which are small,
can be completely attributed

to effects of stereotype, potentially.

There are some as well
that are a little larger and that probably

cannot be completely
due to effects of stereotype.

And I will illustrate this
with a specific example: aggressiveness.

The differences are minimal, however,

they can have a certain importance.

Aggressiveness, how is it measured?

For example, through questionnaires
in which you answer

to dozens of questions
that target your attitudes,

based on your reactions
in several situations.

The scores of all these questions
are gathered and, at the end,

a score out of 200 or 250 is given.

And here you have the distribution
of the men's scores in blue

and the distribution
of women's scores in red.

What you see is that these distributions
are a little staggered:

the men's average is a little higher
than the women's.

You could say that men are, on average,
more aggressive than women.

But, the two distributions
overlap quite a lot,

so there are also a lot of women

who are more aggressive than a lot of men.

You could say,
"This difference is so small

that it has literally no importance."

If we see the data in a different way,

if we interest ourselves
in the proportion of men and women

that go above a certain score,
in the lower scores,

we have one man for one woman,

but when we get to the scores
that are average,

we have two men for one woman.

When we get to 150,
it is four men for one woman.

And at 200, we have eight men
for one woman.

The number is perhaps linked
to another statistic,

which is the perpetrators of homicide.

There are about ten men for one woman.

So we see through this example
that even when an average difference

is very small and there is a large overlap
between the two distributions,

there can be very significant consequences
on a societal level.

So, we have spoken

about the cognitive differences
between genders,

about differences of personality.

There are also differences of preference.

That is to say that spontaneously,
men and women

are attracted to different objects
and activities.

And these differences
are observed from infancy.

From the nursery playgrounds,
we can clearly see that boys

are attracted to games that are a little
more active, competitive, rowdy,

while girls will be more attracted
by calmer games

that are also more social and cooperative.

These are stereotypes,
but also observations

that can be made in very young childen.

Obviously, you can think
that the way in which we educate

boys and girls is not unrelated
to these observations.

But can they explain
these differences entirely?

Can the biases in education explain

these differences completely?

Well, to be sure, it is necessary
to watch younger children,

with appropriated methodologies.

For example, in my laboratory,
we have methods to study

the infant's perception.

For example, you can see
if the infant prefers to look

longer at one visual stimulus or another.

What you observe in this kind
of experiment is that babies,

when they are girls, will prefer
to look longer at the female face,

but when it is boys,
they will prefer to look longer

at this abstract image,
which you do not see,

but there is a string with a ball
that is hanging - a kind of mobile.

You see that from the youngest age,
as it so happens, the experiment shows

that from birth, boys and girls already

have preferences for different objects.

You also see some differences
concerning cognitive capacities,

like the previous mental rotation
in space.

So the 3D object is shown
to this baby and then is turned

and presented in different orientations.

Then, after a few seconds,
the mirror image of this object is shown.

So it is no longer the same
as the rotated object.

What you observe is that baby boys
notice the difference,

and that is shown through an increase
in the amount of time they watch

the new object.

While the girls, you see
on the two left lines, do not show

any difference in the amount of time
they watch.

So, in theory, they do not

notice the difference between
the object and its mirror image.

These are experiments that were
performed between three and five months,

otherwise said, at an age where
it is still not very plausible

that the cognition of these babies
has already been biased

by different treatments
between boys and girls.

So, if there can be differences
as early as this, where do they come from?

Well, we have a small idea
of the mechanisms that are at work.

You know that genetic differences exist

between men and women
in their sexual chromosomes.

The fact that the male fetus possesses
a Y chromosome will differentiate

their testicular gonads, very early,

and their testicles will secrete
testosterone,

that will progressively soak
into the tissues

by reaching a peak around
15 weeks of pregnancy.

But if you look at the dotted line
at the bottom, in the female fetuses,

the testosterone remains at zero
all throughout development.

The fact this testosterone
soaks into all the tissues

will masculinize the tissues,
will change the cells slightly

to have them take on a form
which is specific for the male sex.

This phenomenon is also produced
in the brain and drives structural

and functional differences,
and behavioral differences.

These things are very well
demonstrated in different

animal species because in the animal,
we can conduct experiments

where we manipulate the rate
of fetal testosterone.

You can imagine though
that we don't authorize these experiments

on human beings and consequently,
there isn't formal proof

that the exact same thing
happens with humans.

Despite everything, we do know

that the human being's biology
is compatible

with the idea that the same mechanisms
are at work in the human being.

So, in summary, you saw, yes,
cognitive differences

between men and women do clearly exist.

They are not enormous,

they are moderate sized,
or otherwise said,

they don't justify distribution
of differentiated roles

between men and women in society.

But they are credible.

Some of them can be observed
from infancy, even from birth,

and we begin to recognize,
at least partially,

their cerebral foundations
and hormonal and genetic origins.

So, there are differences.

So what?

Does that justify discrimination
of women in employment, paying them less?

Obviously not!

Because there are differences,
nothing justifies this discrimination,

whatever the differences highlighted.

So it is clear that we are actually
bloody wrong.

It's a matter of confusion between
equality in law and equality in practice.

When you say that human beings
are born free and equal in law,

you're not observing a fact,
you're affirming a value.

We wanted to continue to affirm this value

whatever the observation that can be made,

and whatever the differences
that can be observed between individuals.

Because, in any case,
differences are everywhere,

and they will always be there.

We are all different and, actually,
so that we all can be equal,

it would be necessary
that we all be clones,

and so all the same gender,

and, furthermore, everyone would be raised

in the exact same laboratory conditions.

Does that appeal to anyone?

No? Good.

So differences are everywhere.

Finally, this is also what makes
human life interesting.

It's diversity and this is also
what makes it possible to hope that rather

than being afraid of our differences,
we can try to capitalize on them

and recognize that we also have qualities
that are able to complement one another.

Elsewhere, the idea of justice and equity
is still more important.

What is unjust is to devalue
a person evaluating them

based on average qualities,
real or assumed,

of the gender or of the group
to which they belong.

This is fundamentally unjust,
while justice is simply evaluating people

on the basis
of their individual qualities,

independent of their gender
or another group that they belong to.

To conclude, I think that this
is what is necessary

to vindicate for women.

It's not de facto equality
in every aspect with men.

It's equality in law,
and that is justice and equity.

Thank you.

(Applause)