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The brain's anatomy and psychology, and how these sciences reveal some uncomfortable truths about our thoughts, feelings and desires....
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00:02There are some great questions that have intrigued and haunted us since the dawn of humanity.
00:12What is out there?
00:18How did we get here?
00:23What is the world made of?
00:29The story of our search to answer those questions is the story of science.
00:37Of all human endeavours, science has had the greatest impact on our lives, on how we see the world, on
00:44how we see ourselves.
00:46Its ideas, its achievements, its results are all around us.
00:53So, how did we arrive at the modern world?
00:58The answer is more surprising and more human than you might think.
01:06It is a tale of power, proof and passion.
01:23This time, one of the more intimate questions we've ever asked.
01:29What makes us human?
01:53The question, what is human nature?
01:56What is it that shapes our thoughts, feelings and desires is one that philosophers, writers and religious leaders have all
02:04struggled with.
02:05I am particularly interested in how science has wrestled with this particular question.
02:11And that's not just because it gets to the heart of who we are, but also because it gets to
02:16the heart of what science itself is.
02:24I want to begin with one of the great civilizations of the ancient world, Egypt.
02:36The ancient Egyptians were amongst the first people we know about to really wrestle with the question, what makes us
02:43human?
02:48We humans are acutely aware of ourselves, of the sense of being alive, of living within our own skin.
02:56But where does this me reside?
03:00Where is the control center?
03:02Where is the essence of what I truly am?
03:08Egyptian beliefs about what made us human are revealed in their attitudes to the afterlife.
03:17Certain organs like the stomach, lungs or liver were seen as so critical they were frequently removed, embalmed and put
03:27back inside the body for burial.
03:33The Egyptians believed that the heart was the key to the afterlife, that when you died it would testify to
03:39your good or your bad deeds.
03:42In this papyrus over here you can see a heart being weighed up against a feather.
03:46If it was heavier than the feather then this demon over here would come and eat it and that was
03:51all over for you.
03:52In fact, the idea of being light-hearted or heavy-hearted come from the Egyptians.
03:58And in a way you can understand why they thought that emotions resided in the heart.
04:03But certainly when I have been broken-hearted I felt it in my gut and in my chest.
04:10So, the Egyptians treated the heart with great reverence.
04:16But what about that other organ we now regard as more central to our humanity?
04:26Here at Manchester University, a team of Egyptologists are studying a 2,500-year-old mummy.
04:35An endoscope is going to be pushed up its nose to show me how the Egyptians treated the brain.
04:45Carefully.
04:48As we enter the nose, we go through the nasal septum.
04:54How extraordinary!
04:59It's like going into some sort of hidden cave.
05:01It is, isn't it? It's a secret world, really.
05:06We would normally be stopped from going through there
05:08because of the bone that would separate the brain from the nasal cavity.
05:12Which should be there.
05:13Yes, which should be there, of course.
05:14Right.
05:15And so now you're actually entering the skull.
05:18Yes.
05:23Ooh!
05:24That's sort of the suture in the top of the head, isn't it?
05:28But there seems to be something missing.
05:31Yes.
05:32Yes, there's a brain missing.
05:34How extraordinary.
05:37Did they not see the brain as important?
05:39They recognised that the brain controlled some of the bodily actions,
05:44but they certainly didn't think that the individual personality
05:48was located in the brain.
05:50So they removed it and discarded it.
05:53So they just took it and chucked it?
05:55Yes.
05:55It shows a certain contempt for what we regard
05:57as one of our more important organs now.
05:59Absolutely, yes.
06:01Yes, yeah.
06:04The Egyptian concept of what makes us who we are
06:08was a mystical union between the physical body
06:11and an everlasting spirit.
06:19One of the recurring ideas to emerge out of early civilisations
06:23like the Egyptians was the belief that we are more than simply flesh and blood.
06:28There is something else, something which is special and makes us human.
06:33This conviction is one of the most powerful and enduring in human history.
06:44This belief shaped thinking for millennia.
06:50But as Europe emerged from the Middle Ages,
06:52people started to approach the question differently.
06:58The physical and intellectual frontiers of Europe were changing.
07:02And that would encourage a very different view of who we are.
07:15That new view can be glimpsed here, the grandest royal palace in France.
07:29Amongst this great splendour, there's an intriguing technology
07:34that to me reflects a great change in how we saw ourselves.
07:41Captured in one magnificent room.
07:52This is it.
07:54It's the Great Hall of Mirrors in Versailles.
08:02It is absolutely fantastic.
08:07And the whole room utterly dominated by this wall of mirrors
08:12which extends down almost 100 metres.
08:14I've never seen mirrors on this scale.
08:35This really is cutting-edge technology.
08:40Now, this is not absolutely perfect.
08:42The surface is not completely smooth.
08:44You can see little bubbles here in the glass.
08:47It's not perfect. It's not like a sort of modern mirror.
08:50But the size and the scale is unlike anything which was really done before.
08:55And compared to the sort of curvy-worthy things in
08:58that most people would know of from centuries earlier,
09:01this was something different.
09:04Because there was nothing, nothing, nothing like this
09:07had been developed before.
09:10and allowed people to just stand there and look at themselves and think,
09:14you know, who am I? This is me.
09:18These mirrors represent the culmination of an idea
09:21that had been emerging in Europe since the Renaissance.
09:27The notion that we are all individuals, not members of a class or a guild,
09:35but defined by our own desires, ambitions and destinies.
09:44Along with this growing awareness of self came different questions.
09:48What makes me who I am?
09:51Why do I have these hopes, these fears, these talents, these expectations?
09:58And most importantly of all, what is this I, anyway?
10:12Throughout history, the technology of the age has stimulated new ways of looking at the world.
10:20You can see a thing which looks a little bit, I don't know what it is.
10:22It looks like some sort of sea creature, possibly a prawn.
10:28New inventions have created metaphors to help us think about what makes us human.
10:36This girl makes me smile.
10:41In 17th century France, the philosopher René Descartes
10:45was wrestling with the question of human nature.
10:50For inspiration, he drew on a technological wonder of the age,
10:54water-powered mechanical statues.
11:04The story goes that Descartes is wandering through the Royal Gardens
11:08and he sees a fountain.
11:10And in the middle of the fountain, there is an enormous statue of Neptune,
11:14which is sprouting water a bit like this.
11:17And this particular Neptune, when you come close,
11:19it sort of starts to jab at you with the tribe.
11:22And Descartes is rather taken by this.
11:24And he starts to think, and he thinks,
11:27perhaps animals are just a form of automator.
11:32Perhaps a prawn really has some sort of gears in it
11:36with lots of sort of intersecting bits and pieces.
11:39And then he starts wondering, perhaps that's what our bodies are.
11:43They're just sophisticated machines.
11:47For the time, this was a very daring idea,
11:52to suggest we are like machines.
11:55But it begged the question,
11:57what special quality actually makes us human?
12:04Descartes was a man desperate for certainty.
12:07But this was no time to find it.
12:1617th century Europe was riven by religious and political conflict.
12:23Old certainties of church and state were crumbling.
12:28What, thought Descartes, could he trust?
12:32What could he really know?
12:38Descartes is wracked by doubts,
12:40and he wants to find out something he can believe in.
12:44Imagine, says Descartes, the tower,
12:46the tower is in fact round, but you perceive it as square.
12:50Or for example, this thing here, from a distance,
12:52it probably looks square, but actually when you hold it up,
12:55it is clearly round.
12:56Your vision has been deceived.
13:01And then Descartes wondered if all his senses were deceiving him.
13:07He could feel the warmth of his fire,
13:11see its light, hear its sound.
13:14But he'd experienced the same sensations in a dream.
13:21So perhaps the whole world he was living in
13:23was nothing but an illusion.
13:30Descartes is now beginning to really question everything.
13:33The moon, the sky, the stars.
13:36Perhaps they are all figments of his imagination.
13:39But what about mass?
13:41Two plus three.
13:43It always equals five, doesn't it?
13:44But maybe there is a demon who has taken possession of his brain.
13:49Descartes is really beginning to doubt everything.
13:54Down to the very question of whether he himself existed at all.
14:04And then finally he got there.
14:07He realised that the act of doubting implied a doubter.
14:11There was one thing he could be absolutely certain of,
14:13was the existence of his own thinking, doubting mind.
14:18He summed it up in a neat philosophical phrase.
14:22I think, therefore, I am.
14:28It may be a familiar phrase, but it contains a profound idea.
14:34The claim that the essence of our humanity lies in our thoughts,
14:38our ability to reason.
14:41And reason was to form the basis of a new experimental science.
14:56Across the channel, a much more bloody approach to the question of,
15:00who are we, was to emerge from a great political clash.
15:06The English Civil War.
15:10Oxford was a key royalist stronghold.
15:13For some caught up in the action, turmoil spelt opportunity.
15:21Here in Oxford, a young man called Thomas Willis was part way through his medical training,
15:27which in those days lasted an incredible 14 years.
15:31The Civil War interrupted his studies, which in many ways was a very good thing.
15:40Studying medicine didn't necessarily make you a good doctor, for one very good reason.
15:50Medical teaching was still largely based on ideas from antiquity.
15:56The disruption of his studies gave Willis the opportunity to investigate the body for himself.
16:05By now, people were exploring the anatomy of the brain.
16:10But still, no one really knew what it did.
16:16In the mid-1600s, Willis began a groundbreaking series of dissections.
16:23And I'm about to get a privileged glimpse of what he would have seen.
16:29Ah. There we are.
16:31Human brain. Isn't it wonderful?
16:33It is.
16:34It is utterly unbelievable when you think that this brain once thought it reasoned.
16:41It's a unique feature of the universe, really.
16:46When a brain is sort of fresh, it's a very different consistency, isn't it?
16:49Yes, it is. I tell the students it's a bit like a badly set jelly.
16:53And presumably, if you were to cut that, you really would have great difficulties.
16:56Yes, it would just fall to pieces, really.
17:01Willis was one of the first to use a new technique.
17:07Preserving brains in alcohol.
17:10This made them firm enough to dissect with great precision.
17:15You ready to cut them?
17:17Yes, ready to cut.
17:26Isn't it strange?
17:31Ah.
17:33What's really curious is there's almost no structure or definition to it, is there?
17:39Well, the thing that really catches your eye is the ventricles in the centre, which were what everybody was preoccupied
17:46with before Thomas Willis.
17:49And the idea was that this part of the brain may have acted as a sort of pump and important
17:55activities may have gone on in the fluid that was moving around in the ventricles.
18:00So, in a sense, all this is just muscle and all the thought and the important stuff is somehow taking
18:05place in these holes over here.
18:07Yes, and it was Thomas Willis who realised that the actual structure of the brain was what was critically important.
18:14When Willis looked at animal brains, he concluded our intellect and thoughts must lie in the parts of the brain
18:21animals don't possess.
18:24Thomas Willis was very struck by the corrugated surface of the human brain as compared to the smooth surface of
18:31the sheep.
18:32And this enables a huge volume of cerebral cortex to be contained within the relatively small volume of the skull.
18:40And that's where he thought being human resided?
18:43Yes.
18:44You can see there's a ribbon of cortex going over the surface of the cerebral hemisphere.
18:48Right, you see.
18:49Yes, that's right.
18:50And this cortex was where he realised people were likely to have their thoughts.
19:00Willis had established a link between the state of the brain and the state of the mind.
19:07He wrote the first book specifically about the brain.
19:12The brain was drawn out to others.
19:13From now on, anatomical studies would become one of the great foundations of a scientific explanation of who we are.
19:32Reason was now seen as the pinnacle of human nature.
19:36It had been shaped by philosophical doubt and detailed dissections of the brain.
19:44Europe entered a new age, a celebration of the rational mind.
19:52Faith in reason would underpin the growth of trade and the building of empires.
20:07In 1837, something was causing a stir at London Zoo.
20:16Their first orangutan, Jenny, was introduced to an astonished audience.
20:24Exotic animals were being brought to Britain from across the empire.
20:34Even Queen Victoria herself came calling.
20:42Jenny's arrival would challenge assumptions about what makes us human.
20:48Right, come this way, Michael. I'll introduce you to Batu.
20:51He should be waiting. There he is.
20:54There he is. Hello.
20:56This is Batu.
20:57Wow.
20:58He's big.
20:59Hello.
20:59This is very big.
21:01What a beautiful face.
21:02Very big and very strong.
21:04Right. Can I do this?
21:05Yeah, just be careful with the orange, yeah.
21:07Yeah.
21:09Oh, very delicately done.
21:11He doesn't want to drop it.
21:15He's even ruder than my kids.
21:19That's rude. Stop it.
21:20You could actually see that wonderfully sullen look on his face.
21:23Yeah.
21:24That look of, mmm, don't like that.
21:27It's a very human expression.
21:31Bad behaviour.
21:33Oh, no.
21:34That's terrible.
21:38It's wonderful.
21:39This is a great sense of independence.
21:42Stop it now.
21:44So you've spat at me.
21:46You've played your game.
21:47What are you going to do next?
21:49Come on.
21:52Look at that smelly.
21:59One of the visitors to the zoo was young Charles Darwin.
22:05But this isn't the familiar story about evolution.
22:11His visit to the zoo was part of his lesser known research.
22:19Fascination with animal emotion.
22:24One day Darwin saw something that really astonished him.
22:30Jenny was playing with the keeper.
22:33And the keeper had an apple.
22:34And the keeper was taunting Jenny by waving the apple in front of her
22:38but not letting her get hold of it.
22:40And in Darwin's words, the ape threw herself on her back
22:44and cried precisely like a little child.
22:52Darwin became convinced that the expressions of emotion he saw in Jenny
22:56and in humans were the same.
23:00His research developed over 30 years.
23:07Tenderness, shame, joy.
23:11He saw them all in animals.
23:18Darwin's painstaking work led to one of his most important books.
23:23The expression of the emotions in man and animals.
23:28It was greeted with alarm and fascination.
23:32Now this is a really incredible book.
23:34Partly because of the illustrations.
23:37Because this is one of the first books ever to include photographs.
23:40And they feature people.
23:42People in various states of distress, if you like.
23:45This consulate sad, very sad looking.
23:48He examines it in almost microscopic detail.
23:51There's a very interesting picture here of a woman's forehead.
23:55And he notices these two lines coming up here,
23:58which are later called, in fact, the Darwin grief muscle.
24:04What Darwin was undermining in his work was a fundamental belief.
24:11A belief in human uniqueness.
24:23By suggesting a close kinship with animals,
24:26he'd also opened the lid on the rational mind,
24:30hinting at a dark subterranean world
24:33of instincts, desires, emotions.
24:36The animal within.
24:42Here was an irony for Victorian science.
24:46The power of reason which made us unique
24:50had been turned on ourselves
24:52and revealed us to be less exalted.
24:56less rational than had been suspected.
25:08A new side of ourselves was being unearthed.
25:14Darker and more dangerous.
25:20In Paris, doctors began to explore this untamed side.
25:28At La Salle Petrière.
25:33This imposing looking building was originally used
25:36to store gunpowder.
25:38But then they decided they could put it to better use.
25:40To lock away thousands of people
25:42who were regarded as just as unstable and dangerous.
25:46The destitute and the insane.
25:55It had been Europe's most notorious women's asylum,
25:59with nothing to offer but cruel imprisonment.
26:07These are some of the cells where they kept the women.
26:10And these are the original bars
26:14behind which they were imprisoned.
26:15And there is something terribly poignant
26:18about the idea of thousands of women chained up
26:22in filthy living conditions,
26:25utterly without any prospect of release.
26:29No hope.
26:31No hope at all.
26:36But attitudes were changing.
26:40After years of revolution,
26:42the asylum had become a place of care,
26:44rather than simply imprisonment.
26:50One of its most famous physicians was Jean-Martin Charcot.
26:58Often the best way to understand the normal
27:00is to study the abnormal.
27:04And here there were 5,000 troubled minds to study.
27:12Charcot was one of the first people to try and separate out
27:15and categorise different forms of mental and neurological illness.
27:20He took incredibly detailed notes
27:22and he also took lots of photographs.
27:28One condition in particular had been puzzling doctors.
27:33They called it hysteria.
27:38Patients suffered paralysis, seizures, blindness and violent fits.
27:45Charcot presumed these symptoms were caused by a physical disease.
27:50But then he began to use a remarkable new approach.
27:575...
27:586...
27:59Hypnosis.
28:017...
28:03Charcot found he could induce and relieve symptoms of hysteria using hypnosis.
28:10And become aware of any feelings of lightness.
28:13Going up.
28:14It could produce extraordinary effects in the body.
28:18Drifting up and up now.
28:19And the balloon really sort of taking off now.
28:22And bobbing from side to side.
28:25Okay, can you see the balloon?
28:27I can.
28:28It's a big blue balloon.
28:29Okay.
28:29And it's sort of Winnie the Pooh blue balloon.
28:31Okay.
28:32But you get that feeling of the...
28:34I've tried hypnosis before.
28:36But this is the first time it's really worked.
28:40Okay.
28:41And just notice what's happening there.
28:43Over the course of an hour, I mysteriously lost coordination of my hand.
28:47It kind of gets even more noticeable.
28:49In fact, it's become really shaky now.
28:53I had my hands stuck together.
28:56Knuckles are quite locked.
28:57Oh.
28:58They are quite locked.
28:59And most bizarre of all, one side of my visual field was rendered almost useless.
29:06These are a bit fainter.
29:07Okay.
29:08And I have a sense of something over there, but not really.
29:11Okay.
29:12Not really objects.
29:13Okay.
29:15One, two.
29:17That was extremely odd.
29:20It was a bit like I was there, but I wasn't there.
29:23That he was talking to some other part of me.
29:26And the other part of me was responding.
29:29Higher.
29:30And higher.
29:30And the idea you could just do it with the power of words is quite strange.
29:40Charcot's observations of hysteria led him towards a radical conclusion.
29:48If symptoms could be induced or relieved by hypnosis, then perhaps they were not signs of some pathological disease.
29:56Perhaps they were caused by emotions that the patients themselves were not even aware they were feeling.
30:04Charcot never fully grasped what he was dealing with, what we would now call the unconscious mind.
30:13In amongst the crowds at one of Charcot's famous demonstrations was a young Austrian doctor, Sigmund Freud.
30:23A man who would famously use the study of hidden emotions and repressed urges to develop this extraordinary concept of
30:33the unconscious mind.
30:37Freud's ideas would become a significant cultural influence on the 20th century.
30:46They would join a rising tide of other ideas that would form a wholly new approach to who we are.
30:55Psychology.
31:05A less than rational self had been revealed.
31:11By animals brought back from distant lands.
31:17By changing attitudes to mental illness.
31:21And a new door into the unconscious mind.
31:25We could no longer see ourselves simply as creatures of reason.
31:41By the end of the 19th century, Europe was in the throes of a bold new age of communication.
31:56Thousands of miles of new railway linked the continent's great cities.
32:04Telegraph cables joined people across the globe.
32:09Outro music.
32:13This interconnected world led to a different way of looking at how the brain works.
32:23This new technology naturally enough inspired new metaphors to describe the nervous system.
32:29For example, if I pinch my finger, then the pain fibres go down the line, up into my spinal cord
32:36and from there to the brain.
32:38The thing is, what happens next?
32:40Well, everyone knew there were complicated signal boxes and junctions up there, but nobody knew just how they worked.
32:55The Spanish countryside.
33:03Home to a scientist I deeply admire.
33:07He had a passion for art that would shape his future career as a neuroscientist.
33:17His name was Santiago Ramon E. Cajal.
33:26When he was a young man, Cajal was obsessed by art.
33:31As he later wrote,
33:32I was gripped by an irresistible mania.
33:35I painted everything that captivated my sight.
33:38Earth, foliage, plants, the human form.
33:42He was actually extremely good at putting down on paper what he saw.
33:49Cajal's passion for art was coupled with a fascination for a new technology.
33:55Photography.
33:57This is the sort of camera that Cajal would have used.
34:01I've got it lined up on the mountains now.
34:03I've got a photographic plate in here, which is basically a bit of glass with some photosensitive chemicals on.
34:09And then you lift this, and you trigger the shutter.
34:16Should take about 20 seconds.
34:19When that's done, this goes down, and the glass plate you take away with you, off to the mysteries of
34:25the darkroom.
34:31It was his twin passions, art and photography, that would shape his most important discovery.
34:37What it is that makes the brain work.
34:44To see, observe, and make things visible is one of the great challenges of science.
34:51The challenge for neuroscientists was uncovering the fine structure of the brain.
34:59The task Cajal set himself was to reveal the communication networks that exist inside our heads.
35:10I've come to the Cajal Institute to see how he did it.
35:15I always feel like I'm getting into surgery again.
35:19Great. So, mouse?
35:21Yeah, tricky to brain.
35:23My first job is to chop up a rather slippery mouse brain.
35:28Very small.
35:29Hey.
35:31It's trickier than it looks.
35:33There we go.
35:35It's like cutting onions.
35:37Yes, more or less.
35:38I'm good at cutting onions.
35:40Yeah.
35:44The search was on for a stain that would make the mysterious structure of the brain visible under the microscope.
35:54Cajal was shown a technique using chemicals from the darkroom.
35:59Chemicals that could make brain tissue turn black.
36:03You can see it's a really complicated process.
36:10Cajal spent nearly 20 years fiddling away, doing minor adjustments, just seeking perfection.
36:19The great debate was whether the brain was just a mesh of fibres,
36:24or made or made of distinct individual units.
36:35Placing stained tissue under the microscope, Cajal became convinced that there were individual building blocks in the brain.
36:44Neurons.
36:48Neurons.
36:50Now, that is absolutely beautiful.
36:55Neurons.
36:57That is a neuron.
37:00Neurons.
37:14Neurons.
37:23That is what they were looking for.
37:37Neurons.
37:43Neurons.
37:45Neurons.
37:47Neurons.
37:50Neurons.
37:52Neurons.
37:54Neurons.
37:55Neurons.
37:55Neurons.
37:56Neurons.
37:57Neurons.
37:59Neurons.
38:00Neurons.
38:01Neurons.
38:02Neurons.
38:02Neurons.
38:02Neurons.
38:04Neurons.
38:05Neurons.
38:06Neurons.
38:06Neurons.
38:10Neurons.
38:12Neurons.
38:16Neurons.
38:18Neurons.
38:19Neurons.
38:20Neurons.
38:21We now know there are at least a hundred billion of them and all these connecting branches. Well, there are
38:27trillions of connections and
38:29somewhere in here
38:32emotion and thought are born
38:34Somewhere in here is the answer to what makes a human
38:53Half a century later the world descended into chaos
39:01Out of the turmoil of World War two came a secret invention
39:06Built here at Bletchley Park in rural England
39:13Colossus
39:16The most complex machine that had yet been built
39:21Designed to crack enemy codes it would also shed light on the question of who we are
39:29What was truly astonishing about Colossus was the speed at which it could work
39:35Enemy messages which had previously taken teams of human code breakers six weeks to crack could now be done by
39:42the machine in six hours
39:44It must have seemed truly superhuman
39:50Here was a machine doing something that till now only the intelligent human mind could do but much faster
40:00Once again the technology of the day offered a model for how the brain might work
40:09When you think about it, it's a bit like a primitive brain
40:13With the valves representing the neurons and the wiring representing the connecting axons and dendrites
40:28People had begun to theorize that Cahal's neurons worked a bit like electronic switches
40:36If intelligence could be replicated by the on off switching of a machine
40:41Perhaps the reasoning mind wasn't as uniquely human as we thought
40:49One of the biggest human brains at bletchley was alan turing often called the father of modern computing
40:57In 1950 he thought of an ingenious way of judging whether computers show some form of intelligence by devising a
41:05test
41:09Turing test is actually more of a turing question the question he asked himself was
41:14Would it be possible to build a computer that was so intelligent and so good at
41:20Having chats with humans that you could be chatting to the machine and not be aware that you're not actually
41:25talking to another person?
41:28Well, he suggested that by the year 2000 we would have cracked the problem
41:32We are well beyond that point
41:34Let's see
41:36Right. What is
41:38What is your name?
41:41You don't remember?
41:43No, I don't remember
41:45I'm plugged into one of the more sophisticated programs designed to respond to turing's challenge
41:52Okay, let's try some general knowledge. I mean computers should be able to do general knowledge
41:59It doesn't ever seem to really answer the question
42:03Anyway, this is garbage
42:06Let's try a different tack
42:08favorite films
42:11Transformers 2
42:12Maybe that is some sort of computer joke. I can't believe anybody liked transformers 2
42:18What films make you cry?
42:25Science fiction and comedies. What do you like?
42:29Right. It's not very impressive. I'm not enjoying myself. I'm not having a great conversation here
42:36I
42:37Think what you can learn from this is that computers are good at computing basically crunching numbers and things like
42:43that
42:43What they clearly lack is the thing that really gives any form of human interchange any worth any value
42:52Feelings like humor warmth love affection any of the things that we actually value
43:00Perhaps too much to expect from a machine
43:03Bye
43:04Bye-bye
43:10For centuries technology has provided metaphors to explain who we are
43:16The computer is simply the latest we have seized on
43:20But its failings reveal that what makes us human lies in something a machine cannot do
43:28We are passionate irrational creatures
43:31Often driven by forces. We do not understand
43:47At the turn of the 20th century a great nation was coming of age
43:57The united states
44:11The land of the free personal rights and liberties
44:18This was the perfect home for the thriving discipline that focused on ourselves as individuals
44:27Psychology
44:34Psychology as the name implies originally started out as the study of the psyche or mind
44:41The idea was you could look into yourself introspect and learn about human nature that way
44:47However here in america a small group of psychologists soon decided that was nowhere near rigorous or vigorous enough
44:54They wanted to turn psychology into a science
44:58So they decided to focus on something they really could measure and manipulate
45:03Behaviour
45:11This approach called behaviorism was transformed into a systematic science by one of the 20th century's most controversial pioneers
45:22His name was bf skinner
45:27Skinner was convinced that our behavior is the product of our environment
45:32Learned from our experiences
45:39Since skinner thought that environment was all important
45:42I thought it would be quite interesting to have a look at where he worked
45:46This is his study
45:48Isn't it wonderful
45:52This is completely unchanged from when he died over 20 years ago
45:58He liked music so he had this adapted so he could just pull that and play his music
46:09This is a man who likes to tinker and adjust things
46:15This is the bed in which he used to sleep
46:17It is absolutely filled with his paraphernalia
46:25It was his passion for gadgets for things that he could adapt and change that led him to his greatest
46:31invention
46:32A device which is as iconic to behaviorists as the telescope is to astronomers
46:39The operant conditioning chamber or skinners box
46:46Skinner's experiments would reveal something surprising and very disturbing about the human condition
46:57This is an operant chamber otherwise known as skinner box
47:00It's a skinner box many people in my field still
47:03Dr. Robert Allen uses similar methods to those skinner used
47:07There's an area where the pigeon stands
47:10There are response keys
47:11The pigeon has to peck on these buttons
47:14If it pecks them in the right order it gets a reward
47:17So what are you going to do to impress me with a pigeon today?
47:21I'll show you
47:22Go get a pigeon
47:26Who's this one?
47:27This is G21
47:28G21
47:30I don't think of pigeons as being smart, they must admit
47:32They're very smart
47:33Is he going to demonstrate just how smart?
47:35Indeed
47:35Okay
47:36Indigo G21
47:38Okay
47:41Hungry
47:42It looks like
47:46The pigeon has to work out whether the center light shines red or green for longest
47:53If it's green it has to peck the button on the right
47:56Well he's smart
47:57Long green means go right
47:59Okay
48:01So will he go right?
48:02Yes, he will
48:03You're confident in your bird, don't you?
48:05I am very confident
48:06Very good
48:08If it was red that was longest he has to go the other way
48:11Now he has to go left
48:13Okay
48:14Watch
48:15Yes, he's done it
48:16Yes
48:16He's very good, I have to say
48:18I'm good at predicting behavior
48:20Well done G21, go boy, go
48:23What these experiments showed was how easily behavior could be learned
48:27Even manipulated
48:35I was about to see how quickly this can happen
48:40We are going to shape the turning response by delivering reinforcers for his approximate behavior
48:49You're going to make him sort of turn in a circle, eh?
48:51That's correct
48:52Just better said
48:56Each time the pigeon turns left, Dr. Allen delivers food to reinforce that behavior
49:03Until after just 20 minutes, he has the pigeon dancing round in circles
49:12Pigeons and birdseed may not look controversial
49:15But what was so shocking at the time was that Skinner applied his ideas to human behavior
49:24What Skinner was saying is that we are in many ways like pigeons
49:28That we are the product of the numerous interactions we have with our environment
49:33Whether it's falling in love, the job, the friends you make
49:36All these things which appear to be decisions are actually the product of things that have happened to us in
49:41the past
49:43We can no more exercise free will than this pigeon can decide whether to peck or indeed turn in a
49:49circle
49:55Skinner was convinced his discovery could be used to benefit mankind
50:04We could change people's behavior for the better by changing their environment
50:13But in the context of the cold war
50:15The ability to control behavior left some people fearful it could be misused
50:22Because in skinners view free will was nothing but an illusion
50:31Now most of us believe that being able to make choices is an important part of being human
50:36But here was skinner saying that that was an illusion
50:39That actually it was a piece of pre-scientific nonsense akin to believing in a flat earth or demonic possession
50:46You can imagine how popular that message was in the land of the free and the rugged individual
50:56Behaviorism was soon joined by other approaches through the 1960s and beyond
51:03There were new drugs therapies personality tests new ways to measure our thoughts memories and emotions
51:14Psychology has grown into a vast science as diverse and multifaceted as we are
51:29So who are we?
51:33Well, we are the product of our genes and our environment
51:45Billions of neurochemical reactions firing every single second of our lives
51:55In us reason and emotion are frequently at war
52:03Thoughts passions memories and behavior emerge unbidden out of the depths
52:10Brain scans reveal many parts of the brain operating outside our conscious awareness
52:26We are the product of numerous daily interactions
52:34And the quest to understand the essence of who we are has revealed something fascinating going on inside our heads
52:43Something none of us are ever aware of
52:48I can show you what I mean with a famous visual illusion
52:59It's called the aims room that is so bizarre
53:05Clearly what i'm seeing is i'm seeing a very very tall person over there and a short person
53:11Over there and when they swap over
53:15There's a moment where my brain just goes clunk
53:18I absolutely know this is an illusion but my brain just won't let me see through the illusion
53:28So how's it done well if you come over this way
53:33It's really obvious
53:35Hi there
53:37Thank you
53:38Okay, so essentially the room really dips down here lots of space above my head
53:44There is a sharply sloping floor as i march up the room begins to narrow until i'm really crunched into
53:51the corner
53:53There's very little space between the ground and the top here and that's how
53:56The illusion is created
53:59Essentially the room is a trapezoid
54:06The aims room shows us something very important about how the brain is working
54:12Part of my brain
54:14Which knows the rules of a room it has assumptions models built in there and it knows based on experience
54:23The normally rooms the ceiling and the floor is parallel and that the walls are at right angle
54:31From one particular viewpoint the room looks like it fits that mental model
54:37And the brain has such a powerful belief that this quirky shaped room is normal
54:42That people appear to have changed size
54:47This illusion reveals something fundamental about how the brain works
54:54Our perception of reality is not just based on what is out there but it is also partially constructed
55:01We have these models running in our head and they are constantly being tested against the evidence of our senses
55:16This process of building models in our heads is happening from the moment we are born
55:24This child is using her senses to find out about the world
55:30Is that person in the mirror and now the baby or is it me?
55:36Why does that thing make a noise when i shake it?
55:40What she's doing is constantly learning by testing everything around her
55:48Thousands of little experiments like these will create her unconscious assumptions
55:56They'll build the models that shape her view of the world
56:00That's how she will be able to make her way through life
56:08It is very charming when you think there's in a way what she's doing now is acting rather like a
56:15mini scientist
56:17She's investigating the world
56:19She's forming her theories her hypotheses and she's testing them against reality
56:26And that in a sense is what science is
56:29And it's going on inside each and every one of us from the moment we are born
56:35Is that right Chloe? Is that right?
56:37It is
56:44In this program we've seen that humans are creatures of both rational thought
56:50And emotional turmoil
56:55And in this series i've shown how science too has been shaped by reason and emotion
57:02As well as by the tumult of the world in which it operates
57:09Its intellectual achievements have transformed our lives
57:21But it hasn't been straightforward
57:24The story of science is a messy one
57:27Wrapped up in politics
57:29Belief money and rivalry
57:32Proof forever shaped by power and passion
57:39Science is a very human activity
57:44Something we unconsciously do every day
57:49Observing the world
57:50Building mental models and testing them
57:55But it's when we deliberately started using the scientific method that we went way beyond our individual capabilities
58:05I think science is the greatest collective endeavor that mankind has ever undertaken
58:18Over the last few thousand years the human brain has not changed at all
58:22Evolution does not go that fast
58:25But what has changed is our understanding of the world
58:29We don't have to rely simply on the wisdom of our own brain
58:34We have language we have literature and now we have computers
58:38And that links us all together that gives us if you like the wisdom of all those who have gone
58:44before
58:48And that was the final part of the story of science catch up with the junior apprentices at nine tomorrow
58:55here on bbc hd
58:56but next tonight stay with us for drama in crash
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