Who led the research on the teenage brain?

The research was led by a group at UCL, overseen by the speaker.

How does the speaker usually give talks?

The speaker typically uses science slides but adopted a mixed format for this book talk.

What was the reader Dina Hall's entry in her teenage diary about?

Her entry detailed personal interactions and fashion choices rather than the historic moon landing.

What is the societal view on mocking teenagers, according to the speaker?

Society finds it acceptable to mock teenagers, unlike other age groups.

What is the WHO's definition of adolescence?

The World Health Organization defines adolescence as the second decade of life, ages 10 to 20.

Do adolescents experience peer influence differently than adults?

Yes, adolescents are more influenced by peers, affecting their risk-taking behavior.

What usually influences adolescent risk-taking?

Social situations, particularly peer presence, heighten risk-taking tendencies in adolescents.

When does the brain stop developing according to the speaker?

The speaker suggests the brain never truly stops developing due to its neuroplasticity.

What distinguishes human brain development mentioned in the talk?

White matter increases during adolescence while gray matter decreases.

What comparison does the speaker make with other species?

Adolescent behaviors like risk-taking are observed in other species, such as mice and wombats.

The Neuroscience of the Teenage Brain - with Sarah-Jayne Blakemore

00:56:02

https://www.youtube.com/watch?v=yQXhFa8dRCI

Summary

TLDRThe talk, centered on the teenage brain, delves into 16 years of research conducted at University College London (UCL). The speaker transitions from using scientific slides to a more descriptive approach, reflective of the book they authored on adolescent brain research. A notable reader example emphasizes personal significance versus historic events, showcasing how teenagers prioritize personal and social aspects over the extraordinary. The speaker also highlights societal tendencies to mock adolescents, often ignored for other age groups, and discusses adolescence as a transformative phase for identity and social development. A significant part of the dialogue revolves around defining adolescence, noting differing definitions like that of the World Health Organization and historical perspectives provided by Stanley Hall. The teenage years, marked by a quest for identity and navigating peer influence, are explored with examples showing societal perceptions across cultures and species, such as mice exhibiting similar risk-taking behaviors. The biology of the adolescent brain is meticulously discussed, revealing increases in white matter and decreases in gray matter, an indication of brain maturation. The talk also touches on behavior patterns such as risk-taking, embarrassment, and social influence, with illustrations of how these change across adolescence. The speaker challenges assumptions of adolescence as a dysfunctional stage, asserting its crucial role in developing independence and adult identity. The talk concludes with a passionate recitation from a youth theater production, reinforcing the theme that the adolescent brain is not broken but is in a unique, formative stage of development.

Takeaways

🧠 The teenage brain undergoes significant development, crucial for forming identity and social connections.
📈 Adolescence is defined variably, with no agreed end age, reflecting cultural differences.
🙅‍♂️ Society often mocks teenagers, a unique social acceptance not seen in other age groups.
📉 Gray matter decreases while white matter increases in the adolescent brain, indicating maturation.
🌐 Adolescent behaviors like risk-taking are seen across cultures and species, such as in mice.
👥 Peer influence is a dominant factor in teenage decision-making and risk-taking behaviors.
🔄 The concept of adolescence is not recent; historical figures have noted similar behaviors for centuries.
🌟 The adolescent stage is formative, not flawed, essential for developing independence and adult identity.
📊 Studies show similar adolescent behaviors in diverse cultures, highlighting global patterns.
🎭 A youth theater group's portrayal of the teenage brain reflects societal and personal insights.

Timeline

00:00:00 - 00:05:00
The speaker discusses their long-term research on the teenage brain at UCL, highlighting the importance of adolescence for social self-identity development. They note society's tendency to mock teenagers and emphasize adolescence as integral for becoming independent adults.
00:05:00 - 00:10:00
The speaker addresses the different perspectives on when adolescence ends, mentioning varying views and definitions by different organizations and individuals. They note that cultural differences impact the perception and duration of adolescence, defining it as the period between puberty and achieving a stable, independent societal role.
00:10:00 - 00:15:00
There are universal behavioral patterns during adolescence, including risk-taking and impulsivity, regardless of cultural differences. The speaker highlights studies showing that these behaviors are seen across different cultures and even in non-human species, indicating adolescence is a crucial developmental stage rather than a cultural invention.
00:15:00 - 00:20:00
The speaker shares historical perspectives to illustrate that adolescence has always been seen similarly throughout history, citing philosophers and playwrights. They explain their shift from schizophrenia research to studying the developing teenage brain due to the peak onset age of psychiatric symptoms and encouragement from mentors.
00:20:00 - 00:25:00
Using MRI technology, scientists have learned extensively about brain development. The speaker explains ongoing brain changes during adolescence, including increased white matter and decreased gray matter, and the significance of these changes in cognitive and behavioral development.
00:25:00 - 00:30:00
Neurodevelopment during adolescence involves processes like myelination and synaptic pruning, leading to increased brain efficiency and neuroplasticity. These changes help adapt brain functions to environmental demands and are essential to understanding adolescent behavior and decision-making processes.
00:30:00 - 00:35:00
The speaker discusses the heightened sense of embarrassment and social awareness in adolescents, explaining a study that shows adolescents are more self-conscious and physiologically reactive when they believe others are observing them, compared to children and adults.
00:35:00 - 00:40:00
Adolescents are more likely to engage in risk-taking, especially in social settings, due to peer influence. The speaker emphasizes that risk-taking is not unique to adolescents but is influenced by social contexts where peer approval is sought. Demonstrations and studies illustrate these tendencies and their real-life implications.
00:40:00 - 00:45:00
Participants demonstrate a balloon task to highlight differences in risk-taking behavior among age groups. The experiment showcases the correlation between adolescent risk-taking in controlled tasks and real-life behaviors, emphasizing social influence as a key factor in adolescent risk propensity.
00:45:00 - 00:50:00
A study shows that peer presence significantly increases risk-taking in adolescents compared to adults. The speaker notes policy implications and emphasizes adolescents' hypersensitivity to social exclusion, which can explain certain decision-making behaviors, shedding light on the rationale behind risking social ostracism over health risks.
00:50:00 - 00:56:02
The speaker concludes by advocating for a positive perception of the adolescent brain, likening it to a developmental phase rather than a defective state. They highlight the importance of supporting and celebrating adolescence, underscoring the period's role in shaping individuality and potential, capped off by a youth performance emphasizing similar themes.

Mind Map

Frequently Asked Question

Who led the research on the teenage brain?
The research was led by a group at UCL, overseen by the speaker.
How does the speaker usually give talks?
The speaker typically uses science slides but adopted a mixed format for this book talk.
What was the reader Dina Hall's entry in her teenage diary about?
Her entry detailed personal interactions and fashion choices rather than the historic moon landing.
What is the societal view on mocking teenagers, according to the speaker?
Society finds it acceptable to mock teenagers, unlike other age groups.
What is the WHO's definition of adolescence?
The World Health Organization defines adolescence as the second decade of life, ages 10 to 20.
Do adolescents experience peer influence differently than adults?
Yes, adolescents are more influenced by peers, affecting their risk-taking behavior.
What usually influences adolescent risk-taking?
Social situations, particularly peer presence, heighten risk-taking tendencies in adolescents.
When does the brain stop developing according to the speaker?
The speaker suggests the brain never truly stops developing due to its neuroplasticity.
What distinguishes human brain development mentioned in the talk?
White matter increases during adolescence while gray matter decreases.
What comparison does the speaker make with other species?
Adolescent behaviors like risk-taking are observed in other species, such as mice and wombats.

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00:00:05
[Music]
00:00:09
I'm gonna talk a bit about the teenage
00:00:12
brain this is a subject that I've been
00:00:15
working on for about the last 16 years
00:00:17
I've been running a group at UCL and we
00:00:20
we research the teenage brain and thank
00:00:24
you and actually it's interesting cuz I
00:00:28
have very rarely do I give talks with
00:00:31
notes I normally just have loads of
00:00:33
science slides behind me which I talk
00:00:35
about but because this is a book talk I
00:00:38
thought it would be better to kind of
00:00:39
mix up a few sides with more of a
00:00:42
description which is a sort of
00:00:44
representation of what's in my book so
00:00:46
yeah the last three years in my
00:00:49
so-called spare time I've been writing
00:00:50
about the research that we do on the
00:00:53
teenage brain and I'd like to start this
00:00:55
talk with this nice letter which was
00:00:59
written by a reader who wrote to The
00:01:01
Guardian newspaper so this is Dina Hall
00:01:03
a reader of the Guardian newspaper who
00:01:05
says there's nothing like teenage
00:01:08
Diaries for putting momentous historical
00:01:10
events in perspective this is my entry
00:01:13
for the 20th of July 1969 I went to Art
00:01:18
Center by myself in yellow cords and
00:01:21
blouse Ian was there but he didn't speak
00:01:23
to me got a poem put in my handbag from
00:01:27
someone who's apparently got a crush on
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me it's Nicholas I think oh man landed
00:01:32
on moon
00:01:35
this is a really nice illustration
00:01:38
because it shows us what's important to
00:01:41
that particular teenage girl at that
00:01:43
particular moment in her life less
00:01:45
important is the fact that man happened
00:01:48
to land on the moon for the very first
00:01:49
time that day and more important to
00:01:52
things like what she's wearing who she
00:01:54
likes who she doesn't like who she's
00:01:56
hanging out with adolescence is the
00:01:58
period of life that where we in which we
00:02:01
develop our sense of self our sense of
00:02:03
self-identity and particularly our sense
00:02:05
of social self that is how other people
00:02:08
see us that I think is what adolescents
00:02:11
this period of life that I'm talking
00:02:12
about today is all about it's developing
00:02:15
a sense of who you are and particularly
00:02:18
how other people see you so how you're
00:02:20
seen in your local community that that
00:02:24
is what adolescence is about it's about
00:02:26
constructing ourselves so as John said
00:02:30
we as a society um
00:02:33
appear to think that it's completely
00:02:35
acceptable to mock this age group like
00:02:37
John said whenever I tweet about working
00:02:40
on the adolescent brain invariably I
00:02:43
will get a tweet back saying a tweet
00:02:45
back saying something like well that's
00:02:46
not going to take very long is it
00:02:48
implying I think that there's no brain
00:02:50
defined or it's very small I'm not quite
00:02:52
sure what that implies but I'll always
00:02:54
get some kind of reply jokey reply about
00:02:57
teenagers it's a really interesting
00:02:58
phenomenon that we as a society allow
00:03:02
ourselves to laugh at this age group in
00:03:05
a way and you know there are whole funny
00:03:07
comedy shows on exactly that subject
00:03:10
mocking teenagers and it's interesting
00:03:13
because we don't really find it socially
00:03:15
acceptable to do that with any other
00:03:17
sector of society something about our
00:03:21
view of this age group allows us or
00:03:25
makes it socially acceptable to make fun
00:03:28
of them and also to demonize them a bit
00:03:29
they get they have a very kind of bad
00:03:31
reputation we are very quick to blame
00:03:34
them and to yeah and to sort of blame
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blame their behavior which I'm going to
00:03:41
talk about a lot today on their own
00:03:43
decisions and their you know their own
00:03:45
decision to be Moody and impulsive and
00:03:48
taking and particularly influence that
00:03:51
by their peers and lazy not getting up
00:03:53
in the mornings that kind of thing but
00:03:55
actually adolescence is a really
00:03:57
fascinating period of life and it's a
00:03:59
really important period of life in which
00:04:01
we all have to go through to become
00:04:04
independent adults adolescence is really
00:04:07
fundamental to the adult we become okay
00:04:12
so I'm now going to ask you to get out
00:04:14
your mobile phones and instead of
00:04:15
turning them off I'm gonna ask you to
00:04:18
log on to the Wi-Fi so if you get out
00:04:22
your mobile phones and then once you've
00:04:24
logged on once you've got good Wi-Fi or
00:04:27
good 3G or 4G log on to mint accom Ross
00:04:31
can you show the first mentor question
00:04:33
so now what you have to do is answer
00:04:35
this question what age do you think
00:04:37
adolescent stops so when does this
00:04:40
period of life end and you've got a
00:04:43
multiple choice of five answers there so
00:04:46
if you all just put in what you think
00:04:47
and you there's no you know that I'm not
00:04:49
gonna tell you the answer now it's just
00:04:51
interesting to see whatever whatever one
00:04:53
thinks the answer is to this brilliant
00:05:00
okay so a hundred and ninety four of you
00:05:03
have entered some answer we'll just give
00:05:07
it another few seconds okay we should
00:05:15
probably move on so can we look at the
00:05:16
results so there's quite a spread of
00:05:24
responses and most people are saying age
00:05:27
twenty-five interesting that some people
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are saying never okay
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well I'm going to talk about that now
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actually so what is adolescence what the
00:05:39
definition of adolescence I'm always
00:05:40
asked this and obviously is an obvious
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question there are they actually is
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there's no simple answer
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some people think of adolescence as the
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teenagers as synonymous with the teenage
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years say thirteen to nineteen uh the
00:05:54
World Health Organization defines
00:05:55
adolescence as the second decade of life
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so ten to twenty um
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Stanley Hall who was the first person to
00:06:02
coin the term adolescence to describe
00:06:05
this age group about a hundred and odd
00:06:06
years ago in the u.s. described it as
00:06:09
the period of life between puberty so
00:06:11
around age twelve to thirteen back then
00:06:13
up until about age 25 the the definition
00:06:17
of adolescence that I use and lots of my
00:06:19
colleagues use is the age between
00:06:21
puberty so it starts with the physical
00:06:24
and biological changes at puberty and
00:06:26
the end of adolescence in the way we
00:06:29
define it has a much more fuzzy and
00:06:32
vague definition which is the age at
00:06:34
which you attain a stable independent
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role in society but that's for never
00:06:40
people so that can go on a long time and
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the interesting the interesting thing if
00:06:46
you think about it about that definition
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is how different adolescents this
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concept of adolescence is between
00:06:54
cultures so in our culture it's
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completely normal and socially
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acceptable for young people to be not
00:07:02
independent so to live at home with
00:07:04
their parents in full-time education
00:07:06
throughout their teens of course and
00:07:08
even beyond that into their 20s or even
00:07:10
their 30s whereas in other cultures
00:07:13
around the world that's not the case at
00:07:15
all and young people children are
00:07:17
expected to become independent like earn
00:07:19
their own money and as soon as they can
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and have babies as soon as they reach
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sexual maturity so the concept of
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adolescence and the way and social
00:07:29
expectations of adolescents differ
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vastly between cultures and some people
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have argued because of those cultural
00:07:36
differences of the whole concept of
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adolescence that this this concept is a
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recent in
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vention coined yes by Stanley Hall about
00:07:46
a hundred and ten years ago in America
00:07:47
is something that's new that's invented
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recently but actually I think there are
00:07:51
some really good reasons why that's not
00:07:54
the case and why in fact adolescence is
00:07:57
a really important period of biological
00:08:01
and psychological and social development
00:08:04
before right before I before I tell you
00:08:07
about those reasons I'm gonna ask you to
00:08:09
answer a couple more questions so can we
00:08:11
can we have the next question so get
00:08:12
your phones back out mentee it will go
00:08:14
if you just refresh the page you'll get
00:08:16
the next question so when at what age do
00:08:20
you think the human brain stops
00:08:22
developing
00:08:39
okay so can we showed the results no
00:08:46
it's interesting so most people are
00:08:47
saying never and some people are saying
00:08:49
24 and some 30 okay I'll come back to
00:08:53
that later one more question if you go
00:08:55
press refresh okay the question this is
00:08:58
a tricky question the question is how
00:09:00
many neurons does a newborn baby's brain
00:09:03
contain but I'm going to give you a clue
00:09:05
so the clue is that it's an adult human
00:09:07
brain so most people in this room an
00:09:10
adult human brain contains 80 around 86
00:09:14
billion neurons so knowing that how many
00:09:18
neurons does a newborn human babies
00:09:20
brain contain okay can we show the
00:09:34
results so most people think newborn
00:09:40
brain contains 240 billion and some
00:09:44
people 86 billion okay I will come back
00:09:46
to those later on in the talk and can
00:09:49
you go back to my slides now please Ross
00:09:53
thanks okay so I mentioned that there
00:09:57
are these big cultural differences in
00:09:59
the way we think about adolescence but
00:10:01
nevertheless it seems that certain
00:10:03
adolescent typical behaviors by which I
00:10:06
mean behaviors like behaviors that we
00:10:08
stereotypically associate with this age
00:10:10
group so behaviors like increased risk
00:10:13
taking or impulsivity peer influence
00:10:17
heightened self-consciousness behaviors
00:10:21
that we we tend to think of when you
00:10:23
when you hear the word teenager or
00:10:24
adolescent you can see those behaviors
00:10:26
across cultures even in cultures where
00:10:29
societal expectations of this age group
00:10:31
vastly differ so there was one
00:10:34
experiment there are actually very few
00:10:36
experimental research studies looking at
00:10:39
that it's really hard to do as you can
00:10:41
imagine but there was one study
00:10:42
published a couple of years ago and she
00:10:44
probably published about one year one
00:10:45
and a half years ago by Larry Steinberg
00:10:48
and his colleagues they studied
00:10:50
different behaviors across 11 different
00:10:53
cultures and these cultures are very
00:10:55
different in terms of how young people
00:10:57
are treated and the expectations placed
00:11:00
on those young people nevertheless they
00:11:03
showed pretty similar developmental
00:11:05
trajectories of two particular behaviors
00:11:08
one is sensation-seeking
00:11:10
sensation-seeking is defined as the
00:11:14
desire to seek novelty and to take risks
00:11:18
and across those 11 different cultures
00:11:21
although there were some subtle
00:11:22
differences most of those cultures
00:11:25
showed a very similar developmental
00:11:27
pattern for sensation-seeking which is
00:11:29
this so this what you can see here is
00:11:31
sensation-seeking plotted on this axis
00:11:34
here at the vertical axis plotted
00:11:36
against age from 10 to 30 so
00:11:40
sensation-seeking increases during the
00:11:43
teenage years its highest in the late
00:11:45
teens which is what that bar corresponds
00:11:48
to here and then it decreases again
00:11:50
during the 20s so across cultures there
00:11:55
seems to be a peak in sensation-seeking
00:11:57
and risk-taking in the late teens and
00:12:00
then that declines again whereas
00:12:03
self-regulation which is the ability to
00:12:07
regulate and plan your behavior and
00:12:09
inhibit risk-taking stop stop you're
00:12:12
stopping yourself taking risks has a
00:12:15
different development or pattern which
00:12:17
is really similar across these 11
00:12:18
different cultures so across those
00:12:21
cultures sensation sensation seeking
00:12:23
sorry self-regulation improves gradually
00:12:27
during the teenage years and it levels
00:12:29
off into the 20s so teenage typical
00:12:34
behavior like sensation-seeking and also
00:12:36
the ability to regulate your impulses
00:12:39
and your actions appear to be pretty
00:12:42
invariant across cultures also across
00:12:45
species so interestingly adolescence is
00:12:49
not specific to humans it's not just
00:12:52
humans who go through undergo this
00:12:54
period of life all animals go through a
00:12:57
period of life between puberty and
00:12:59
becoming fully sexually mature adults
00:13:02
in that period of their lives you can
00:13:04
measure their behavior and lots of
00:13:06
scientists do this all around the world
00:13:07
particularly with mice and rats mice and
00:13:10
rats go through about 30 days of
00:13:12
adolescence between going through
00:13:15
puberty and becoming fully sexually
00:13:17
mature adults and in those 30 days you
00:13:19
can see increases in things like
00:13:21
risk-taking
00:13:22
and exploration of their environments
00:13:25
and changes in the way they behave
00:13:26
socially in their social behavior there
00:13:29
was one study published a few years ago
00:13:32
showing that adolescent mice drink more
00:13:34
alcohol when they're with other mice but
00:13:38
that's not the case for adult mice so
00:13:39
this this this this graph shows that
00:13:42
results so here's the amount of time
00:13:44
that the mice spend drinking alcohol
00:13:47
when they're on their own here this is
00:13:51
the blue bar is the adolescent mice and
00:13:53
the red bar is the adult mice so they
00:13:55
drink around the same amount when
00:13:57
they're on their own but when they're
00:13:58
with their cage mates adolescent mice
00:14:01
drink lots more than they did when
00:14:03
they're on their own whereas a lot mice
00:14:05
drink around the same so adolescent
00:14:08
typical behavior isn't restricted to
00:14:11
humans but you can also see it in other
00:14:13
species as well there's a nice quote I
00:14:16
dig out quote I look for and keep quotes
00:14:19
about adolescents from various
00:14:20
newspapers again this is from the
00:14:22
Guardian I don't know if you remember
00:14:23
you probably don't but about three years
00:14:26
ago two or three years ago a woman in
00:14:28
Australia was attacked by an adolescent
00:14:30
wombat it didn't really make front-page
00:14:32
news but it did make neat the newspapers
00:14:35
or at least the Guardian and the
00:14:36
Guardian had a quote from a guy called
00:14:38
Martin Lynde who was from the Australian
00:14:41
Wildlife Service and I'm not going to do
00:14:43
this in an Australian accent but you can
00:14:44
imagine it in an Australian accent he's
00:14:47
talking about adolescent wombats
00:14:49
he says as babies they're clingy they're
00:14:53
adorable they're with mum 24 hours a day
00:14:56
they're in a soft snuggly sleeping bag
00:14:59
all the time listening to a heartbeat
00:15:00
when they start to mature and hit
00:15:03
puberty they just hate everybody and
00:15:05
everything they go from running between
00:15:07
your legs and cute as a button to being
00:15:09
absolute little can I swear little shits
00:15:12
they nip you
00:15:14
Rek they bite I won't look after
00:15:16
adolescent wombats because you kiss
00:15:18
goodbye to your flooring and everything
00:15:20
they just destroy everything I saw
00:15:22
that's really nice because it could
00:15:23
equally be written about adolescent
00:15:26
humans okay
00:15:29
history the third reason why I think we
00:15:32
shouldn't think of adolescents as some
00:15:34
kind of recent Western and phenomenon is
00:15:37
because if you read descriptions of this
00:15:40
age group throughout history there are
00:15:41
many you see striking similarities with
00:15:45
the way we describe this age group today
00:15:47
so in this kind of stereotypical
00:15:48
slightly mocking slightly denigrating
00:15:51
way I'm gonna read you a few quotes so
00:15:54
this is Socrates almost two and a half
00:15:56
thousand years ago talking about youth
00:15:57
he says the children now love luxury
00:16:01
they have bad manners contempt for
00:16:03
authority they show disrespect for
00:16:06
elders and love chatter in the place of
00:16:08
exercise they all these people really
00:16:11
quite irritated with adolescents some
00:16:13
reason this is Aristotle who says the
00:16:17
young are in character prone to desire
00:16:19
and ready to carry out any meaningful
00:16:21
desire they may have formed into action
00:16:23
their changeful to and fickle in their
00:16:26
desires which are as transitory as they
00:16:28
are vehement for their wishes are keen
00:16:30
without being permanent they are
00:16:32
passionate irascible and apt to be
00:16:35
carried away by their impulses youth is
00:16:38
the age when most people are devoted to
00:16:40
their friends or when people are most
00:16:42
devoted to their friends or relations or
00:16:44
companions as they are then extremely
00:16:46
fond of social intercourse and have not
00:16:49
yet learnt to judge their friends or
00:16:51
indeed anything else by the rule of
00:16:53
expediency if the young commits a fault
00:16:56
it's always on the side of excess and
00:16:58
exaggeration for they carry everything
00:17:00
too far whether it be their love or
00:17:03
hatred or anything else I mean there's a
00:17:05
two and a half thousand years ago by
00:17:07
Aristotle very similar stereotypes to
00:17:10
the way we we sort of stereotype this
00:17:12
age group today Shakespeare that 400
00:17:14
years ago in The Winter's Tale says I
00:17:16
would there were no age between ten and
00:17:19
three and twenty or that youth would
00:17:22
sleep out the rest for there is nothing
00:17:24
in the between but getting wenches with
00:17:26
child wronging the ancient tree
00:17:28
stealing fighting reso in about a
00:17:33
century laughter Shakespeare says a
00:17:36
change in he's describing adolescence he
00:17:38
says a change in humor frequent anger a
00:17:40
mind and constant agitation makes the
00:17:43
child almost unmanageable his
00:17:45
feverishness turns him into a lion he
00:17:48
disregards his guide he no longer wishes
00:17:50
to be governed so for millennia then
00:17:52
adolescence has been paid it painted in
00:17:55
the same stereotypical terms as we often
00:17:57
use them today this certainly suggests
00:17:59
that adolescence is not some kind of
00:18:01
recent Western phenomenon so when did I
00:18:06
become interested in adolescence John
00:18:08
mentioned my PhD I did my PhD here in
00:18:11
London a long time ago on schizophrenia
00:18:14
which as you may know is a really
00:18:16
devastating psychiatric condition that's
00:18:19
characterized by symptoms like hearing
00:18:22
voices auditory hallucinations hearing
00:18:24
voices inside your head and delusions of
00:18:28
persecution or paranoia so thinking that
00:18:30
other people are out to get you and
00:18:31
you're being followed by mi5 or other
00:18:35
people trying to harm you in some way
00:18:37
I also did postdoctoral research on
00:18:40
schizophrenia in France and what I
00:18:42
noticed after testing or during testing
00:18:45
many hundreds of patients in hospitals
00:18:48
both in the UK and also in France is
00:18:51
that every time I asked a patient what
00:18:54
age did you start experiencing these
00:18:56
symptoms without a single exception they
00:18:59
all said at some age between 18 and
00:19:02
around 26 so I became interested in why
00:19:05
this was what is it about teenage brain
00:19:09
development that is different in
00:19:12
teenagers who go on to develop
00:19:14
schizophrenia at that time that was
00:19:16
around year 2001 very little was known
00:19:20
about how the human brain develops
00:19:22
virtually nothing was known about how
00:19:25
the human teenage brain develops so it
00:19:28
was around then that I decided to change
00:19:30
the focus of my own research and to
00:19:32
start studying the adolescent brain and
00:19:34
I have to say an acknowledge at this
00:19:37
point the support of one of my mentors
00:19:39
Professor hooter fris who
00:19:41
um she had been a mentor to me for many
00:19:44
years
00:19:45
I had been supervised by Christmas who
00:19:48
is her husband and they I couldn't make
00:19:50
it unfortunately but some of you may
00:19:51
have been seen there joined talked here
00:19:54
about six months ago so I was supervised
00:19:57
by Chris but it was very much one of my
00:19:59
mentors and she encouraged me to take
00:20:02
this risk because it really was a risk
00:20:04
switching fields from working with
00:20:06
patients with psychosis to working on
00:20:10
the developing brain because I had never
00:20:12
before done a developmental study but
00:20:15
without his encouragement I changed the
00:20:17
focus of my own research and and have
00:20:20
been doing that ever since
00:20:23
okay so um I asked you when you think
00:20:27
the brain stops developing and how many
00:20:30
neurons you think there are in a newborn
00:20:32
baby brain and I did that for a reason
00:20:34
because when I when I started to become
00:20:39
interested in this area and like I said
00:20:41
and and up until that point I had always
00:20:44
been taught that the human brain mostly
00:20:47
develops in very early childhood and
00:20:50
stops developing at some point in mid
00:20:52
childhood that's what I had learned
00:20:54
during my undergraduate degree I know
00:20:57
that because I kept my undergraduate
00:20:59
textbooks and I still have them and they
00:21:01
say things like that they talk about how
00:21:03
human brain development stops in
00:21:05
childhood and that's because that's
00:21:07
completely wrong and that that's a dogma
00:21:12
that false dogma that we were taught was
00:21:15
simply because actually no one really
00:21:16
knew and they were making an informed
00:21:18
guess based on mostly based on animal
00:21:21
research and on research with
00:21:23
post-mortem human brains but since
00:21:25
around the mid 90s scientists all around
00:21:29
the world have been able to scan the
00:21:32
living human brain of all ages using MRI
00:21:36
scanning so some of you may have had an
00:21:37
MRI scan either for clinical reasons or
00:21:41
for research that's what it looks like
00:21:43
you lie inside the tube of an MRI
00:21:45
scanner and that kind of scanner can be
00:21:48
used to scan your body or your brain in
00:21:50
research in neuroscience we're really
00:21:52
interested in
00:21:53
using MRI to for example tell us about
00:21:57
the structure of the human brain that's
00:21:59
what you can see here and we measure
00:22:01
using these structural MRI images we
00:22:04
measure things like the volume of gray
00:22:05
matter and the volume of white matter so
00:22:08
if I just take my brain here mostly gray
00:22:11
matter is found in the surface of the
00:22:12
brain in the cortex which is just
00:22:14
underneath the skull and gray matter
00:22:17
contains neuronal cell bodies and
00:22:20
connections between cells finances
00:22:23
amongst other things and we also measure
00:22:26
white matter which is mostly found in
00:22:28
the center of the brain and white matter
00:22:31
white matter contains the long fibers
00:22:36
along which electrical impulses pass
00:22:39
from neuron to neuron and they those act
00:22:42
they're called axons those axons allow
00:22:44
neurons and brain regions to communicate
00:22:47
with each other so we are able with MRI
00:22:49
to measure the amount of gray matter and
00:22:52
white matter the human brain contains
00:22:54
and look at how that changes across the
00:22:56
lifespan we also use MRI to scan the
00:23:00
brain while it's active so while you're
00:23:02
doing a particular task and we cook a
00:23:04
brain activity and how that changes
00:23:06
across the lifespan so one of those MRI
00:23:09
studies taught us about the developing
00:23:11
brain the answer is a huge amount so we
00:23:15
if we if we focus on the structural
00:23:17
studies and the amount of gray matter
00:23:20
and white matter of the brain contains
00:23:22
so first of all white matter we know
00:23:24
from many many studies but including one
00:23:27
that's been done recently by many people
00:23:30
including Kate Mills Kate was a PhD
00:23:33
student here with me at UCL she's now
00:23:36
she's now a an assistant professor at
00:23:39
Oregon at the University of Oregon and
00:23:41
Christiane Tammuz who is at the
00:23:43
University of Oslo amongst many other
00:23:46
people looked at MRI scans from many
00:23:50
different people many different children
00:23:52
and adolescents in four different places
00:23:54
so at NIH in Pittsburgh which are both
00:23:57
in the USA in Leiden in the Netherlands
00:24:00
and Oslo in Norway so in total not 391
00:24:06
parties
00:24:07
since children adolescents young adults
00:24:09
were scanned and each one was scanned
00:24:12
every couple of years as they got older
00:24:14
so this is a longitudinal study of of
00:24:18
brain development and altogether we were
00:24:21
analyzing 852 MRI scans from different
00:24:24
people so what you can see first of all
00:24:26
is that the amount of white matter in
00:24:29
the brain increases across childhood and
00:24:32
adolescence so this this is the amount
00:24:35
of white matter in the brain plotted
00:24:37
against age from 5 to 30 and that in all
00:24:41
of the four different cohorts so that
00:24:44
that's what these words correspond to
00:24:46
here the four different cohorts so NIH
00:24:49
and Pittsburgh and light Leiden and
00:24:52
ozlowe all of them showed a significant
00:24:56
linear increase in white matter white
00:24:59
matter increases about one percent per
00:25:02
year
00:25:03
throughout the whole of adolescence so
00:25:05
the brain is increasing the amount of
00:25:08
white matter it contains but
00:25:10
interestingly it's not getting bigger
00:25:13
the brain does not get bigger from about
00:25:15
age eight or nine from about age eight
00:25:17
or nine the human brain is pretty much
00:25:20
adult size so the brain doesn't grow but
00:25:23
the amount of white matter
00:25:24
it contains increases and at the same
00:25:27
time the amount of gray matter decreases
00:25:30
perhaps not surprisingly the whole brain
00:25:32
isn't growing so something has to
00:25:33
decrease and that's gray matter and
00:25:35
that's what you can see here so this is
00:25:37
gray matter across the cortex so the
00:25:39
surface of the brain the whole of the
00:25:41
surface of the brain averaged again in
00:25:44
the four different cohorts showing a
00:25:46
very similar pattern of a gray matter
00:25:50
being highest in late childhood and then
00:25:53
decreasing during adolescence and
00:25:55
plateauing off into the 20s
00:25:56
um the brain loses about 1.5 percent of
00:26:00
its gray matter
00:26:01
each year during the period of
00:26:04
adolescence so it's a really substantial
00:26:05
decrease in gray matter now that might
00:26:08
sound bad it might sound like neuro
00:26:11
degeneration or decline but actually we
00:26:13
don't think it we don't think this
00:26:15
decline in gray matter represents any
00:26:17
kind of degeneration and
00:26:19
we partly because it then plateaus off
00:26:22
and stabilizes for many many decades and
00:26:24
doesn't change after that but also
00:26:26
because of what we think is going on at
00:26:29
a cellular level to underlie this
00:26:32
decrease in gray matter so that's what
00:26:34
I'm going to talk about now
00:26:35
why does gray matter decrease and white
00:26:37
matter increase during adolescence well
00:26:40
the first thing to say is that we don't
00:26:42
actually know because MRI scans although
00:26:44
they give us these beautiful pictures of
00:26:45
the human brain they don't show us the
00:26:48
brain at the level of the of the cells
00:26:50
or the sign APS's for that we have to go
00:26:54
to animal studies and to studies of
00:26:56
post-mortem human brain tissue which we
00:26:59
can look at on slices of under a
00:27:01
microscope and from those studies we
00:27:04
know that during adolescence three
00:27:06
really important neurodevelopmental
00:27:08
processes are happening
00:27:10
the first is myelination which is where
00:27:13
the axons those fibers along which
00:27:15
electrical impulses travel become coated
00:27:18
in a substance called myelin it's a
00:27:21
fatty substance and it appears white
00:27:23
under the microscope and that is what
00:27:25
white matter corresponds to when we when
00:27:28
we see it in MRI scans so myelination
00:27:31
the axons are being coated in myelin
00:27:33
which by the way enables the the signal
00:27:38
transmission to be speedier it speeds up
00:27:41
signal transmission along the axon and
00:27:43
we know that that's happening during the
00:27:45
period of adolescence which is probably
00:27:47
why you see this increase in white
00:27:48
matter in the brain also axons are
00:27:52
growing so those fibers are growing in
00:27:53
diameter and that will also speed up the
00:27:56
signal of the transmission speed of the
00:28:00
signals along the axon and it will also
00:28:02
result in an increase in white matter
00:28:04
during adolescence as seen in MRI and at
00:28:08
the same time and by the way if the
00:28:11
brain is not growing then as it becomes
00:28:13
more white it has to have a concomitant
00:28:15
decrease in gray matter
00:28:17
so that will account partly for the
00:28:19
decrease in gray matter we see but both
00:28:21
of those processes are really important
00:28:24
neurodevelopmental mechanisms and
00:28:26
another third neurodevelopmental
00:28:28
mechanism that's happening in
00:28:30
adolescence is synaptic pruning whereby
00:28:33
finances that are being used in a
00:28:35
particular environment remain and are
00:28:38
strengthened and sign apses that are not
00:28:41
being used in that particular
00:28:42
environment are the ones that get pruned
00:28:45
away and eliminated and in that way the
00:28:49
environment plays a role in shaping the
00:28:51
development of the brain during the
00:28:54
period of adolescence and these all
00:28:56
these three processes can lead to
00:28:57
increased neuroplasticity during
00:29:00
adolescence so hightly the way the brain
00:29:02
adapts to its environment and changes
00:29:05
according to environmental stimuli um
00:29:08
okay so just to go back to those
00:29:10
questions that I asked you about the
00:29:12
brain so when does the human brain stop
00:29:14
developing well in some ways it's a
00:29:16
trick question it's question I'm asked
00:29:17
all the time by the way in the context
00:29:19
of things like ages of consent age of
00:29:21
criminal responsibility yeah legal
00:29:24
implications when children when young
00:29:26
people should be able to vote that kind
00:29:28
of thing and actually it's not really a
00:29:31
question that makes much sense because
00:29:33
firstly we don't really know what her
00:29:36
adult brain looks like I mean maybe we
00:29:38
won't one day but at the moment we don't
00:29:40
have a kind of clear idea of what a scan
00:29:42
of an adult brain versus a child brain
00:29:44
would do it like certainly not in a
00:29:45
single scan single subject level also
00:29:49
there's a sort of age range different
00:29:51
different brain regions develop at
00:29:54
different rates
00:29:55
there are huge individual differences so
00:29:58
different people's brains develop at
00:30:00
different rates and finally in some ways
00:30:04
and I think lots of you answered it
00:30:06
never stops developing I think that's
00:30:07
right the brain never really stops
00:30:09
changing at least this these kinds of I
00:30:11
mentioned neuroplasticity there's no age
00:30:14
limit to neuroplasticity whenever you
00:30:16
learn anything new something probably a
00:30:18
few cells and sign APS's and your brain
00:30:20
have changed they've grown stronger and
00:30:22
there's no age limit to that you can
00:30:25
learn new things at any age because of
00:30:27
neuroplasticity and the the third
00:30:30
question I asked you about how many
00:30:32
neurons does a beta noob or baby brain
00:30:34
contain okay so the answer was exactly
00:30:38
the same as an adult brain eighty six
00:30:40
billion and I it's a kind of trick
00:30:42
question and it's a bit mean because a
00:30:44
lot of you answered I
00:30:46
240 billion or whatever that the the
00:30:48
figure that was higher than the number
00:30:51
of neurons in the adult brain but
00:30:53
actually the number of neurons the
00:30:55
number of cells which is what you can
00:30:57
see here the diagram of in the brain
00:30:59
doesn't change very much at all there's
00:31:02
some neurogenesis there's some
00:31:04
generation of new neurons not very much
00:31:06
and there's some neuronal death again
00:31:08
not much the the change that the the
00:31:12
number of neurons remains pretty stable
00:31:14
throughout life from birth all the way
00:31:16
into old age what changes is the number
00:31:19
of sign APS's and that and you are right
00:31:22
that the number of sign APS's is hugely
00:31:26
greater in childhood the brain massively
00:31:29
over produces silences in childhood and
00:31:33
then it has to get rid of those sign
00:31:35
answers and that is where synaptic
00:31:36
pruning comes in so when I was a
00:31:43
teenager most teenage typical behaviors
00:31:46
which I've talked about a lot were put
00:31:48
down to changing hormones and changing
00:31:52
and sort of social changes like changing
00:31:53
schools but actually now we know that
00:31:57
the brain changes hugely as well these
00:32:00
changes in the brain are at least part
00:32:03
of the jigsaw puzzle in trying to
00:32:04
understand adolescent the transition of
00:32:08
adolescent and adolescent typical
00:32:10
behavior so what are some of these
00:32:13
behaviors well one is embarrassment
00:32:14
embarrassment is something that really
00:32:16
seems to kick in in adolescents
00:32:19
particularly embarrassment in front of
00:32:20
your parents one of my friends said to
00:32:22
me that the the main difference that he
00:32:25
noticed in his children before his two
00:32:27
daughters before and after puberty was
00:32:30
in their levels of embarrassment
00:32:32
particularly in front of him so before
00:32:33
puberty if they were messing around in
00:32:35
us in a shop say he would say stop
00:32:37
messing around on I'll sing your
00:32:38
favorite song and they would instantly
00:32:40
be quiet and to sing to them and after
00:32:42
puberty that became the threat
00:32:45
the idea of their dad singing in public
00:32:48
was enough to make them behave there are
00:32:51
so many examples of adolescent
00:32:53
embarrassment I have a friend who
00:32:55
recently bought a pair of blue trainers
00:32:58
and his 14 year old son immediately said
00:33:00
did you choose them off the
00:33:02
midlifecrisis shelf and he's banned from
00:33:06
wearing those trainers in the entire
00:33:08
village in which his two teenage sons go
00:33:10
to school and they make him keep a pet a
00:33:12
spare pair of shoes in the car just in
00:33:14
case he forgets that rule even my own
00:33:16
children so I'm a governor at my
00:33:18
children's school the primary and the
00:33:20
secondary school both of them and the
00:33:22
difference between my 10 year old and my
00:33:24
13 year olds reaction to this is just
00:33:26
startling so my tenure we had a recent
00:33:28
visit for governor's to the schools my
00:33:30
10 year old was like can I organize your
00:33:32
visit can I show you around I'm gonna
00:33:33
ask my teacher for I can show you around
00:33:34
my 13 year old said looking really
00:33:37
horrified oh my god do you mind if I
00:33:39
pretend not to know who you are so why
00:33:43
is this well there's a there was a study
00:33:45
carried out by Leia Somerville at
00:33:48
Harvard a few years ago where she put
00:33:50
people in an MRI scanner and she
00:33:53
recorded brain activity well she told
00:33:55
them that they were being observed so
00:33:58
she said occasionally when you're lying
00:34:00
in this tiny tube a red light will come
00:34:02
on in front of you and that indicates
00:34:03
that you're being observed by two people
00:34:05
your own age in the in the scanning
00:34:08
control room in fact this is just a
00:34:09
cover story and they weren't being
00:34:11
observed but what she found was that
00:34:13
during the when the red light came on
00:34:15
when when people thought they were being
00:34:17
observed that led to increases in the
00:34:21
self rated level of embarrassment in the
00:34:24
adolescents compared with children and
00:34:26
adults also the amount of sweat the skin
00:34:29
produces which is a which is a measure
00:34:31
of stress was highest in the adolescents
00:34:34
higher than in children or adults and
00:34:36
part of the social brain called the
00:34:39
medial prefrontal cortex which is right
00:34:41
at the front in the middle of the brain
00:34:43
its activity was higher in adolescence
00:34:46
than in adults so there seems to be
00:34:49
something kind of physiological
00:34:51
underlying this increased
00:34:53
self-consciousness we feel as
00:34:55
adolescents
00:34:58
okay I'm going to talk about risk-taking
00:35:00
which is another adolescent typical
00:35:02
behavior we worry about teenagers taking
00:35:06
risks and actually I mean there are so
00:35:10
many examples of this but one one
00:35:11
example that I experienced recently a
00:35:14
couple of summers ago I was driving home
00:35:17
and I I was on an a road very fast very
00:35:23
dark a road in the middle of the night
00:35:25
driving home from Oxford to my house in
00:35:28
Hartford sure and I noticed a girl
00:35:31
walking along this road I mean
00:35:32
pitch-black road cars going 60 miles an
00:35:35
hour occasional occasional cars so I
00:35:36
stopped and said well you know do you
00:35:39
want a lift home where you going she got
00:35:40
in the crash yes that would be nice and
00:35:42
turned out she'd been in a pub she was
00:35:44
at 18 she'd been in a pub she's having a
00:35:46
great time with her friends she spent
00:35:48
her taxi money on beer she had let her
00:35:51
phone ran out of battery she was filming
00:35:53
her friends put on Facebook or whatever
00:35:55
probably not Facebook actually that's
00:35:56
really uncool with young people
00:35:59
she obviously the buses had stopped I
00:36:02
mean so she was gonna walk home I said
00:36:04
alright how far is your home eight miles
00:36:06
away so she was planning to walk eight
00:36:08
miles in the middle of the night and I
00:36:09
feel that you know that's the kind of
00:36:11
thing I probably would have done when I
00:36:13
was 18 but I wouldn't dream of doing it
00:36:14
now there is something about adolescence
00:36:17
which does make us as adolescent when
00:36:19
we're adolescents more susceptible to
00:36:22
taking risks but what I think is really
00:36:26
important is the the idea that it's not
00:36:28
just as simple as that
00:36:30
not all adolescents take risks lots of
00:36:32
adults take risks lots of risks are
00:36:34
really beneficial we learn by trial and
00:36:36
error and risks can benefit us and also
00:36:39
the the context of risk-taking this
00:36:43
particularly the social context like the
00:36:45
girl I picked up the young woman I
00:36:47
picked up it's all about being out with
00:36:49
her friends that's why she was willing
00:36:51
to take the risk of of not abandoning
00:36:56
all her safe ways of getting home
00:36:58
because she was having fun with her
00:36:59
friends so in the kind of heat of the
00:37:01
moment particularly when with friends I
00:37:02
think that's when adolescents are most
00:37:04
likely to take risks
00:37:05
okay I've now got a demonstration
00:37:10
experiment risk-taking experiments so
00:37:12
this is a balloon it's called it's
00:37:14
called um it's called the Bart task
00:37:16
which is the balloon analog risk-taking
00:37:18
task it's a very weird task but it's
00:37:21
very interesting then I'll tell you
00:37:22
about it afterwards so I need some
00:37:24
volunteers I need eight volunteers
00:37:26
preferably of different ages but it
00:37:29
doesn't really matter if not any okay
00:37:38
you come down you come here it's quite
00:37:39
hard for me to say yeah sure and you are
00:37:43
we yeah you - yeah great when yeah we
00:37:44
need a mixture of genders you okay we've
00:37:54
got one two three four five six two more
00:37:58
yeah you one more you okay so what I
00:38:03
want you to do now there's a there's a
00:38:05
prize in this what I want you to do is
00:38:09
blow up these balloons as much as you
00:38:12
can as big as you can and the two people
00:38:16
whose balloons have the biggest
00:38:18
circumference the conference will win a
00:38:20
signed copy of my book I don't know
00:38:24
whether that's really a prize or not but
00:38:25
anyway I've got them here and if I ever
00:38:29
eat Jack and Jerry - if you can come
00:38:30
down cuz they're gonna they're gonna
00:38:31
measure with these very scientific
00:38:33
instruments they're not scientific tool
00:38:36
and they're also different which is
00:38:37
probably a problem but anyway this
00:38:39
circumference of these balloons and
00:38:43
they're also gonna take our name so and
00:38:46
be careful cuz the balloons can pop so
00:38:51
you want to you want to blow up the
00:38:52
balloon and when you think you've got it
00:38:53
as big as you can without it popping try
00:38:56
and tie a knot in it and give it to one
00:38:59
of my assistants Jack Andrews is doing a
00:39:03
PhD with me and Javita lung is about to
00:39:06
do a PhD do
00:39:16
okay so I think your your um so yeah if
00:39:24
you if you measure the balloons yeah I
00:39:34
can you you can do some estimation this
00:39:39
is not a real experiment there's a
00:39:42
digital version of this task that you
00:39:45
can do on a computer and interestingly
00:39:46
okay so that the finding is that
00:39:50
adolescents take more risks on this on
00:39:52
this kind of task where they're
00:39:54
incentivized like they're gonna win a
00:39:55
reward I was just about to say um they
00:40:03
take an owner or they take more risks in
00:40:05
other words that balloons blow up more
00:40:07
than adults please do because they what
00:40:09
they want to win and they want to take
00:40:10
the risk of and it is interestingly
00:40:12
because it's such a weird task if you do
00:40:20
it on line it's obviously much more
00:40:22
controlled than this but it's a way to
00:40:23
ask but it's the the level of
00:40:26
risk-taking that you show on this task
00:40:28
is correlated with real-life risk-taking
00:40:30
like experimenting with drugs or
00:40:32
cigarettes or alcohol which is really
00:40:34
interesting
00:40:38
this is not a scientific version of the
00:40:41
star so we don't have to read anything
00:40:42
into this with these results so who won
00:41:02
[Applause]
00:41:11
so I mentioned that the the key fact the
00:41:16
key factor in in risk-taking in
00:41:19
adolescence seems to be social influence
00:41:21
there's something about being with
00:41:24
friends that make adolescents more
00:41:26
susceptible to taking risks and that was
00:41:29
shown really nicely in an experiment
00:41:30
that was carried out by Larry Steinberg
00:41:33
and their colleagues a few years ago
00:41:34
where they they had they asked
00:41:36
participants to carry out this driving
00:41:38
video game where you drive around a
00:41:39
circuit as quickly as possible and he
00:41:42
measures the number of risks you take
00:41:43
and he he studied various different age
00:41:46
groups and what you can see here is the
00:41:47
number of risks taken by adolescents
00:41:51
these are aged 13 to 16 here in this
00:41:53
leftmost
00:41:55
graph bar young adults aged 17 to 24 and
00:42:00
adults aged 25 and over and what you can
00:42:03
see is actually when they're on their
00:42:04
own when they can focus on the task at
00:42:06
hand
00:42:07
there's very little difference in the
00:42:08
number of risks adolescents and adults
00:42:10
take so this stereotype that adolescents
00:42:13
always take risks is not is just the
00:42:15
stereotype it's not always true however
00:42:17
in a second condition the research has
00:42:20
asked the participants to bring a couple
00:42:22
of friends with them and those friends
00:42:24
just stood behind the participants as
00:42:26
they carried out exactly the same
00:42:27
driving task and that resulted in three
00:42:30
times the number of risks taken by the
00:42:33
13 to 16 year olds and twice the number
00:42:36
of risks taken by the 17 to 24 year olds
00:42:38
and it had no effect on risk-taking in
00:42:40
adults so what this shows is that peer
00:42:43
influence is the really critical factor
00:42:45
in risk-taking and these kinds of data
00:42:48
are very much borne out by by real-life
00:42:53
data from car insurance companies so car
00:42:55
insurance companies as you may know when
00:42:58
you make a claim after an accident you
00:43:00
have to fill in a lot of information
00:43:03
about the precise circumstances in which
00:43:05
the accident took place and that data is
00:43:07
quantified and analyzed and what what it
00:43:10
shows is that young people under the age
00:43:12
of 26 have more accidents than older
00:43:15
people that's why their premiums are
00:43:16
higher but also it shows that the
00:43:19
precise circumstances in which
00:43:22
young people are most likely to have
00:43:23
risk have accidents is when they have
00:43:27
similar aged passengers in the car with
00:43:29
them and that's not the case for adults
00:43:31
for whom having a passenger in the car
00:43:34
is protective you're less likely to have
00:43:36
an accident if you have a passenger if
00:43:37
you're over the age of 26 and there are
00:43:40
now policy implications there are
00:43:42
countries that have brought in
00:43:44
legislation which doesn't allow young
00:43:47
people to carry non-family related
00:43:51
passengers in the car with them for a
00:43:53
couple of years after they've passed
00:43:54
their test and car insurance companies
00:43:56
are also doing the same same kind of
00:43:58
thing so why is it that adolescents are
00:44:00
particularly susceptible to peer
00:44:03
influence well one possibility that we
00:44:06
have been looking into is that
00:44:08
adolescents might be hypersensitive to
00:44:10
being excluded by their peer groups they
00:44:12
might be really worried about being
00:44:16
ostracized by their peer group and we
00:44:18
did an experiment a few years ago
00:44:20
looking at the effect of social
00:44:22
exclusion in adolescents and this was an
00:44:26
experiment using cyber ball which is
00:44:28
this kind of online bull throwing game
00:44:31
so you're you're told so this is you
00:44:33
down here and you're going to be you're
00:44:35
going to be playing game of catch over
00:44:37
the Internet with these two other
00:44:38
players in fact that's just a cover
00:44:40
story there are no other players and we
00:44:42
program those other two players either
00:44:44
to include you in the game of catch or
00:44:46
to exclude you and this looks this we
00:44:49
did this experiment many years ago when
00:44:52
people were like wow that's so cool you
00:44:55
can play a game of catch with people
00:44:57
over the internet now I don't think
00:44:58
anyone would believe that this is a real
00:45:00
game you can do something so much more
00:45:02
sophisticated on your own phone okay
00:45:04
this is what an exclusion condition
00:45:06
looks like so you get thrown the ball
00:45:09
you can decide who to throw it back to
00:45:11
and they could throw it back to you
00:45:12
these are the players
00:45:13
but in this case they don't they just
00:45:15
continue playing with each other for
00:45:16
about two minutes and that makes you
00:45:18
feel really sad it that decreases mood
00:45:24
and increases anxiety in adults so with
00:45:27
cat Sebastian who was my PhD student
00:45:30
many years ago she now runs her own lab
00:45:32
at Royal Holloway we wondered what would
00:45:34
happen
00:45:34
to adolescents if they took part in this
00:45:37
task and I'm going to go through the
00:45:39
results so these are the results in the
00:45:41
adult group this is their mood as
00:45:44
measured by a standardized mood
00:45:46
questionnaire sorry at baseline so
00:45:50
that's the yellow before they taken part
00:45:52
in the experiment and after being
00:45:54
included in that game of catch that's
00:45:56
shown in green and then after being
00:45:59
excluded that's shirt that's their mood
00:46:01
and blue so the adults that took part in
00:46:03
our experiment showed a significant
00:46:04
decline in mood after being after being
00:46:08
socially excluded which is what other
00:46:10
people had already found and the
00:46:11
adolescent group so we tested a group of
00:46:14
11 to 14 year olds here and a group of
00:46:17
14 to 16 year olds they both showed the
00:46:19
same pattern of results as the adults
00:46:21
but their drop in mood was significantly
00:46:24
greater than the adults so what this
00:46:27
suggests is that adolescents are
00:46:29
hypersensitive to to being socially
00:46:33
excluded so what does this mean for
00:46:38
adolescent behavior well if you think
00:46:41
about if you think about this
00:46:44
hypersensitivity to social exclusion and
00:46:47
the need to avoid being socially
00:46:49
excluded to avoid what you might call
00:46:51
taking a social risk it sheds adolescent
00:46:55
typical behavior in a more rational
00:46:57
light so one of the questions I'm often
00:47:00
asked by teachers or parents is why a
00:47:02
perfectly kind of intelligent and
00:47:04
educated young person might make a
00:47:06
decision like try a cigarette when they
00:47:09
know all about the health risks of
00:47:11
smoking but if you think about the
00:47:12
situation in which most young people do
00:47:14
that kind of take that kind of risk it's
00:47:16
when they're with their friends so if
00:47:18
you if you imagine a you know a thirteen
00:47:19
year old who is out with her friends at
00:47:22
the weekend and they offer her a
00:47:23
cigarette
00:47:24
what for her is the more risky decision
00:47:26
saying yes to a cigarette when she knows
00:47:28
all about the health risks of smoking or
00:47:31
saying no and potentially being
00:47:33
ostracized by her peer group well we
00:47:35
would argue that that social risk weighs
00:47:37
in much more heavily for young people
00:47:40
because they're driven to affiliate with
00:47:42
their peer group and to be included by
00:47:45
their peer group now that's not to say
00:47:46
that it's a good idea
00:47:48
but it's it sheds those kinds of
00:47:50
adolescent typical behaviors in a more
00:47:52
rational light but I wanted to end by
00:47:55
showing that we're all influenced by
00:47:58
other people so if you can get back onto
00:48:00
your phones and again go to mentee calm
00:48:08
and Ross if you could go to the fourth
00:48:12
question okay so without any discussion
00:48:21
this is really hard just have a think
00:48:24
about this what the circumference of the
00:48:27
London Eye is
00:48:39
okay I think we're going to move on so
00:48:41
don't ruff don't show the results yet if
00:48:44
you just go on to the next question now
00:48:47
in small groups so in groups of like
00:48:50
four or three or four or five just next
00:48:52
to you it's exactly the same question
00:48:55
discuss for 45 seconds only how the
00:49:01
circumference of the London Eye
00:49:42
okay now you need to vote again
00:49:48
stop talking and vote again so each of
00:49:50
you should vote again and you're not
00:49:56
allowed to google it obviously okay
00:50:03
everyone needs to vote again in each
00:50:06
individual person needs to vote again
00:50:07
we're just like add up to about 200 I
00:50:10
think that was the last one
00:50:16
okay so Ross if you could go back to the
00:50:19
previous question and show the results
00:50:22
from that all over the place okay I can
00:50:29
tell you that the real the true answer
00:50:31
is 424 which actually I think got the
00:50:33
least the least number of votes and okay
00:50:39
so that was when you were not discussing
00:50:41
I have no idea but this is gonna work by
00:50:43
the way um Ross can you show the results
00:50:46
of the next question anyway the main
00:50:53
point here is to show it doesn't matter
00:50:56
about the actual results but to show how
00:50:58
we are influenced by other people we are
00:51:01
all influenced by others everything we
00:51:03
do if we do it when we're with other
00:51:05
people is slightly different comparable
00:51:07
with when we do it on our own we are our
00:51:11
behaviors change when we're in groups
00:51:13
removing crowds our cognitive
00:51:16
performance for example is different if
00:51:18
we're being observed by someone else
00:51:21
compared with when we're not being
00:51:22
observed and new perhaps experience that
00:51:24
just now just discussing things with
00:51:26
other people makes you think differently
00:51:28
about about questions and about
00:51:30
decisions so I'm going to end there just
00:51:33
to say that Stanley Hall when he first
00:51:37
described this period of court that he
00:51:39
called adolescence um
00:51:40
described it in a very kind of rich
00:51:43
broad way he talked about things like
00:51:45
indifference lethargy and melancholy
00:51:47
energy and exuberance he talked about
00:51:51
adolescents reflecting a combination of
00:51:54
uninhibited childish
00:51:55
selfishness and an increasing idealism
00:51:59
in virtue and although many of his
00:52:00
stereotypes have just been dismissed as
00:52:03
caricatures he was right I think to
00:52:05
highlight the importance of friendships
00:52:07
and peer influence in adolescence as
00:52:09
well as the urge to explore the world
00:52:11
with curiosity and energy and to
00:52:13
experience novelty these are
00:52:15
characteristics that are the focus of
00:52:17
much of today's research on the
00:52:19
adolescent brain um to end I want to say
00:52:23
that the adolescent brain isn't broken
00:52:25
we shouldn't think of it as a kind of
00:52:26
dysfunctional or defective
00:52:28
adult brain it's a formative period of
00:52:31
life when the brain is changing in
00:52:33
really important ways and we shouldn't
00:52:35
demonize it we should understand it and
00:52:37
nurture it and support adolescents and
00:52:40
celebrate adolescence um when a few
00:52:43
years ago I had an amazing opportunity
00:52:45
to work with the what was then called
00:52:47
the Islington community theater they're
00:52:48
now called company three a group of a
00:52:50
very big group of young people it's a
00:52:52
youth theatre company in Islington and
00:52:55
they were writing and performing a play
00:52:57
called brainstorm which was their
00:53:01
interpretation of the science of the
00:53:03
teenage brain and this had ended up
00:53:05
having two runs at the National Theatre
00:53:07
to a critical acclaim and we're very
00:53:09
lucky to have one of the stars of
00:53:11
brainstorm here Yaman Chowdhury and I'm
00:53:14
going to sit down while he gives his
00:53:17
main soliloquy from brainstorm
00:53:22
[Applause]
00:53:32
you say to me your brain is broken it's
00:53:38
like an adult's brain but it doesn't
00:53:41
work properly you say when you become a
00:53:45
teenager something happens your brain
00:53:48
shrinks or something it stops working
00:53:51
properly
00:53:51
it gets so full of thinking about
00:53:53
yourself that you forget about anyone
00:53:56
else it's like you're in a city you've
00:53:59
never been to and you don't have a map
00:54:01
and you don't know what you're doing and
00:54:03
you keep taking the wrong turns you say
00:54:09
listen to me
00:54:11
don't worry one day you'll be okay
00:54:14
probably your brain will start working
00:54:18
properly one day your brain will be just
00:54:22
like mine and then you'll be okay
00:54:25
but until then you've got to try and be
00:54:27
more like me I say to you my brain isn't
00:54:36
broken it's beautiful I'm in a city I've
00:54:42
never been to and I see bright lights
00:54:44
and new ideas and fear an opportunity
00:54:48
and a thousand million roads all lit up
00:54:51
and flashing there are so many places to
00:54:54
explore but you've forgotten that they
00:54:56
exist because every day you walk the
00:54:58
same way with your hands in your pockets
00:55:00
and your eyes on the floor I say my
00:55:05
brain isn't broken it's like this for a
00:55:08
reason I'm becoming Who I am and I'm
00:55:13
scared and you're scared because who I
00:55:17
become might not be who you want me to
00:55:20
be or who you are and I don't know why
00:55:25
but I don't say it's all going to be
00:55:27
okay
00:55:27
there are so many things I stop saying
00:55:30
to you I want to say them but I don't I
00:55:36
pick up my
00:55:37
wait put in the kitchen and go upstairs
00:55:42
thank you
00:55:43
[Applause]