0:00:05 > 0:00:08There's a lot of noise in this operating theatre,
0:00:08 > 0:00:11but I want you to listen out for something.
0:00:11 > 0:00:15In preparation for this patient's neurosurgery,
0:00:15 > 0:00:19doctors have put electrodes into his brain to record the activity.
0:00:21 > 0:00:25Through a speaker, we can hear the firing of individual neurons.
0:00:28 > 0:00:32He's agreed to help me with an experiment about decision-making.
0:00:34 > 0:00:35OK.
0:00:35 > 0:00:39Can you tell me what you're seeing? So this is very simple.
0:00:39 > 0:00:40'Without him knowing it,
0:00:40 > 0:00:45'his brain will decide whether this is a rabbit, or an ostrich.
0:00:45 > 0:00:46'It could be seen as either.'
0:00:48 > 0:00:50What do you say, an ostrich?
0:00:51 > 0:00:53'As his brain comes to a decision,
0:00:53 > 0:00:55'there's a subtle change in the audio.
0:00:57 > 0:00:59'It's buried in that pup-pup-pup.'
0:00:59 > 0:01:01SCRATCHING SOUND
0:01:02 > 0:01:05This is the sound of a decision getting made.
0:01:05 > 0:01:08We're eavesdropping on single neurons working in consult
0:01:08 > 0:01:12with billions of other neurons to land on a choice.
0:01:12 > 0:01:14And this is what every decision
0:01:14 > 0:01:17in the history of the human species looks like.
0:01:17 > 0:01:21Every marriage proposal, every declaration of war,
0:01:21 > 0:01:24every leap of imagination, every mission we've launched,
0:01:24 > 0:01:28every bit of human magic looked just like this.
0:01:30 > 0:01:34'Our brains are constantly making decisions.
0:01:34 > 0:01:37'Some we're aware of, most we're not.
0:01:39 > 0:01:44'Deciphering what we hear or see or smell, these are decisions.
0:01:44 > 0:01:48'So is being afraid, falling in love,
0:01:48 > 0:01:51'giving in, resisting.
0:01:51 > 0:01:56'Decision-making is what allows us to navigate a course through life.
0:01:58 > 0:02:01'And your lifetime of choices has sculpted you into the person
0:02:01 > 0:02:04'you are right now.'
0:02:16 > 0:02:21'No matter how easy your day seems, your brain is always hard at work.
0:02:21 > 0:02:25'Making choices, weighing up different options.
0:02:27 > 0:02:30'And it's often in a state of conflict.
0:02:30 > 0:02:33'Locked in a great power struggle with itself.
0:02:35 > 0:02:37'Let me show you what I mean.
0:02:39 > 0:02:42'Right now, I have to make a momentous decision.
0:02:44 > 0:02:49'Mint frozen yoghurt, or lemon?
0:02:49 > 0:02:52'This is serious business because I like both.'
0:02:54 > 0:02:59And inside my brain, this choice unleashes a whirlwind of activity.
0:03:03 > 0:03:06Neurons are wildly getting in touch with one another.
0:03:06 > 0:03:08They're forming competing networks.
0:03:10 > 0:03:13One favours the zing of the zesty lemon.
0:03:13 > 0:03:15The other, the freshness of the mint.
0:03:18 > 0:03:24'When I finally go for the lemon, I have no real idea why I chose it.
0:03:24 > 0:03:27'But if I could see under the hood, I would find
0:03:27 > 0:03:30'that the lemon network has fought harder and won,
0:03:30 > 0:03:32'squelching my mint network.'
0:03:34 > 0:03:36But it's not just mint versus lemon.
0:03:36 > 0:03:38I'm wondering whether to eat this yoghurt at all.
0:03:38 > 0:03:40Because part of me wants it,
0:03:40 > 0:03:42but part of me knows that it's fattening.
0:03:42 > 0:03:45And it's because of this sort of conflict that we can get
0:03:45 > 0:03:50angry at ourselves and cuss at ourselves and cajole ourselves.
0:03:50 > 0:03:52Who's talking with whom, exactly?
0:03:52 > 0:03:55It's only you, right? But it's different parts of you.
0:04:01 > 0:04:05These rivalries are with us in every decision that we make.
0:04:05 > 0:04:08They're usually so easily resolved that we're unaware of them.
0:04:09 > 0:04:13But in some situations, they show themselves.
0:04:13 > 0:04:15We can feel the tug of different networks.
0:04:17 > 0:04:19'I'll show you what I mean.
0:04:19 > 0:04:22'If I can find a willing volunteer.'
0:04:22 > 0:04:25Excuse me, do you want to participate in an experiment?
0:04:25 > 0:04:27- I don't think so.- OK.
0:04:28 > 0:04:31Excuse me, do you guys want to participate in an experiment?
0:04:31 > 0:04:33This will only take 30 seconds.
0:04:33 > 0:04:35- We're running late.- OK. OK.
0:04:42 > 0:04:45- Would you participate in an experiment for 30 seconds?- OK.- OK.
0:04:45 > 0:04:48So here's what you're going to do. Put your hands out, OK,
0:04:48 > 0:04:51- and I'm going to ask you to name the colour of the ink.- OK.
0:04:51 > 0:04:54- OK, so, what colour is that ink? - Red.- Good. OK.
0:04:54 > 0:04:56- What colour is that ink?- Blue.
0:04:56 > 0:04:58'This is a pretty easy task.'
0:04:58 > 0:05:00Green. Red.
0:05:01 > 0:05:05'But introduce a conflict between the word
0:05:05 > 0:05:09'and the colour of the ink and the situation changes.'
0:05:10 > 0:05:13Blue. Yellow.
0:05:13 > 0:05:16Orange. Orange.
0:05:16 > 0:05:17Blue.
0:05:17 > 0:05:19- DAVID CHUCKLES - Green.
0:05:21 > 0:05:22- Er...blue.- OK.
0:05:22 > 0:05:24Orange. Green.
0:05:24 > 0:05:26Blue. Er...
0:05:26 > 0:05:28THEY CHUCKLE
0:05:28 > 0:05:29Orange.
0:05:29 > 0:05:30Blue.
0:05:30 > 0:05:33- Green. - THEY LAUGH
0:05:33 > 0:05:37- I had to close my eyes! - Yeah, I saw that.
0:05:39 > 0:05:43It's hard because of rivalries playing out inside the brain.
0:05:43 > 0:05:46One network is involved in naming colours,
0:05:46 > 0:05:51another has a lifetime of training in reading words.
0:05:55 > 0:05:57'With both networks battling it out,
0:05:57 > 0:06:00'you can directly experience the conflict.
0:06:02 > 0:06:05'To get the right answer, you have to actively suppress
0:06:05 > 0:06:07'the word-reading to name the colour.
0:06:11 > 0:06:15'There are occasions when rival networks can't be reconciled.
0:06:15 > 0:06:17'And those offer a special insight.'
0:06:20 > 0:06:22In this rare footage,
0:06:22 > 0:06:27we can see conflict in the brain expressing itself in the body.
0:06:30 > 0:06:33Psychologist Matt Roser is a specialist in a condition
0:06:33 > 0:06:36known as alien hand syndrome.
0:06:39 > 0:06:42This is a rare side effect of a split-brain surgery
0:06:42 > 0:06:45which is sometimes used to treat epilepsy.
0:06:53 > 0:06:55Split-brain surgery is the disconnection of the two
0:06:55 > 0:06:58hemispheres of the brain, the two halves of the brain.
0:07:00 > 0:07:04By cutting the brain in half, you control the epilepsy better.
0:07:07 > 0:07:11In this patient, it has further disturbing consequences.
0:07:12 > 0:07:14It affects all her motor skills,
0:07:14 > 0:07:17particularly the movement of her hands.
0:07:18 > 0:07:22She can do what the doctor asks with one half of her body.
0:07:22 > 0:07:24Can you lift your hands up in the air?
0:07:24 > 0:07:29But she has no conscious control of the other half.
0:07:29 > 0:07:32Can you give me a thumbs up with this hand? Give me a thumbs up.
0:07:34 > 0:07:36Show me the index finger...
0:07:36 > 0:07:40Her right brain takes control of her left hand and fights for attention.
0:07:42 > 0:07:44What's going on? Tell us what's going on.
0:07:45 > 0:07:48Can you show me your pinkie? OK, great.
0:07:49 > 0:07:52Can you take your pinkie and touch your forehead, please?
0:07:52 > 0:07:55The hand just doesn't respond to commands.
0:07:55 > 0:07:58It seems to have a will of its own.
0:07:58 > 0:08:03Because now there are almost like two half patients inside one body.
0:08:03 > 0:08:07Can you show me your thumb? Show me your thumb.
0:08:07 > 0:08:09For this patient,
0:08:09 > 0:08:13her alien hand syndrome was eventually brought under control.
0:08:13 > 0:08:15'Something's wrong!'
0:08:16 > 0:08:20But the disorder reveals something that's normally hidden.
0:08:20 > 0:08:23giving us a window into the struggle
0:08:23 > 0:08:26that's waged inside our heads every day.
0:08:28 > 0:08:31Can you show me your thumb? Show me your thumb.
0:08:40 > 0:08:42In the business of decision-making,
0:08:42 > 0:08:46two big systems that often come into conflict
0:08:46 > 0:08:50are those we can summarise as reason and emotion.
0:08:53 > 0:08:57These systems work together, so we're generally not aware
0:08:57 > 0:09:00that more than one thing steers our decisions.
0:09:03 > 0:09:07'But some situations can tease them apart.
0:09:10 > 0:09:13'Consider the trolley dilemma.'
0:09:13 > 0:09:16- Hi.- Hi.- I'd like to invite you to step into this booth here
0:09:16 > 0:09:19and we're going to show you a video and just ask you
0:09:19 > 0:09:23- a question about what you would do in this sort of scenario.- OK.
0:09:27 > 0:09:30You see a train trolley whose brakes are broken.
0:09:30 > 0:09:33It's barrelling down the track out of control.
0:09:34 > 0:09:37In its path, you see four workers.
0:09:41 > 0:09:45They're too far away to warn, but if you don't do something,
0:09:45 > 0:09:47they face certain death.
0:09:50 > 0:09:52Then you see a lever.
0:09:54 > 0:09:57If you pull it, you'll divert the trolley onto another track
0:09:57 > 0:09:59and those four workmen will be saved.
0:10:01 > 0:10:06But here's the thing. Another man is working on the other track.
0:10:09 > 0:10:12If you pull the lever, he will definitely die.
0:10:13 > 0:10:16So, do you pull the lever?
0:10:29 > 0:10:31What do I do now?
0:10:31 > 0:10:34- OK, did you pull the lever? - I pulled the lever.- OK, great.
0:10:34 > 0:10:37Now here comes scenario two. There's one more scenario.
0:10:37 > 0:10:39OK, great. Here we go.
0:10:41 > 0:10:44This time, the dilemma is slightly different.
0:10:44 > 0:10:49There are still four workers in the path of the out-of-control trolley.
0:10:51 > 0:10:54But now there's no lever, no way to divert the trolley.
0:10:56 > 0:11:00Instead, there's a large man standing on a water tower
0:11:00 > 0:11:01next to the track.
0:11:01 > 0:11:04Push him off into the trolley's path
0:11:04 > 0:11:08and his weight will be enough to stop the trolley.
0:11:08 > 0:11:12You'll be sacrificing one to save the others.
0:11:12 > 0:11:15So, do you push the man?
0:11:23 > 0:11:26- OK, did you push the man off? - Absolutely not.
0:11:26 > 0:11:30- What did you do in the first scenario? Pull the lever? - I pulled the lever.
0:11:30 > 0:11:33Because it's trading one life for four lives, right?
0:11:33 > 0:11:36So, what's the difference between the two scenarios?
0:11:36 > 0:11:39The physical crime tag of causing death,
0:11:39 > 0:11:42even though I could see where they were the same thing,
0:11:42 > 0:11:44they would have the same results,
0:11:44 > 0:11:48my gut feeling was...was adverse to that.
0:11:50 > 0:11:53Everyone I ask makes the same choice.
0:11:53 > 0:11:57They'll pull the lever, but they won't push the man.
0:12:06 > 0:12:08OK. HE LAUGHS
0:12:09 > 0:12:12It's the same ethical dilemma in both cases.
0:12:12 > 0:12:15Would you trade one life for four?
0:12:15 > 0:12:18In the first scenario, it's just a math problem.
0:12:18 > 0:12:21In the second one, you have to physically interact
0:12:21 > 0:12:23with the man, push him to his death.
0:12:23 > 0:12:27And that recruits other networks in the brain involved in emotion.
0:12:29 > 0:12:32So, what's going on behind the scenes?
0:12:34 > 0:12:38The conflict is being played out across the brain.
0:12:38 > 0:12:41At first, the logic system dominates.
0:12:41 > 0:12:45But introduce the idea of killing a man with your bare hands
0:12:45 > 0:12:50and the emotion system comes online, tipping the balance.
0:12:50 > 0:12:53You're caught between competing drives,
0:12:53 > 0:12:58with the result that your decision can change entirely.
0:13:03 > 0:13:07The trolley dilemma sheds light on real-world situations.
0:13:14 > 0:13:16Think about modern warfare.
0:13:19 > 0:13:24When you launch a long-range missile or pilot a drone,
0:13:24 > 0:13:30or program a cyber attack, these cause damage at a distance.
0:13:32 > 0:13:35The rational networks are at work,
0:13:35 > 0:13:38but not necessarily the emotional networks.
0:13:40 > 0:13:43Detachment reduces internal conflict.
0:13:43 > 0:13:47It's more like pulling the lever than pushing the man.
0:13:50 > 0:13:53War is easier to wage at a distance.
0:14:00 > 0:14:04If we're capable of bypassing our emotional systems,
0:14:04 > 0:14:05why do we have them at all?
0:14:10 > 0:14:14So often in neuroscience, we learn most about the brain
0:14:14 > 0:14:16when things go wrong.
0:14:19 > 0:14:22For two decades, Tammy Myers had a successful career
0:14:22 > 0:14:25as an engineer and a happy marriage.
0:14:28 > 0:14:31Then, two years ago, there was an accident.
0:14:38 > 0:14:41That morning, we got up and rode about an hour.
0:14:44 > 0:14:45From what my friends tell me,
0:14:45 > 0:14:49we went into a 90-degree turn that was not marked.
0:14:53 > 0:14:54And, um...
0:14:55 > 0:14:58..tried everything we could to get around the turn, the bike went down.
0:15:01 > 0:15:03From there, I don't remember anything.
0:15:05 > 0:15:10Tammy recovered from the crash, but one problem remained.
0:15:12 > 0:15:14We're going to need four, cos...
0:15:14 > 0:15:18She now struggles to make even the simplest decisions.
0:15:18 > 0:15:20I don't... I don't...
0:15:23 > 0:15:26I don't...I don't care.
0:15:26 > 0:15:29I'm going to start crying and I don't want to cry.
0:15:29 > 0:15:32But there's too many things in there.
0:15:34 > 0:15:36There's good days and there's bad days
0:15:36 > 0:15:40and you don't necessarily know what day it's going to be
0:15:40 > 0:15:42when you wake up in the morning.
0:15:44 > 0:15:47'I'm waiting for the day that...'
0:15:49 > 0:15:51You know, that she's normal.
0:15:54 > 0:15:57I can't make any... It's too many things
0:15:57 > 0:15:59for my brain to process.
0:15:59 > 0:16:01That sounds absolutely stupid!
0:16:01 > 0:16:03SHE SOBS
0:16:03 > 0:16:07Tammy's brain damage is in the prefrontal cortex.
0:16:09 > 0:16:12Her logic and emotion systems have become disconnected.
0:16:12 > 0:16:14They're still working,
0:16:14 > 0:16:17but her emotions are no longer linked to her intellect.
0:16:19 > 0:16:24Tammy's injury reveals that even in the most basic situations,
0:16:24 > 0:16:27emotion is a necessary component of decision-making.
0:16:29 > 0:16:33To understand the damage, Tammy's neurologist, Dr Eslinger,
0:16:33 > 0:16:36has brought her here, to the grocery store.
0:16:39 > 0:16:44'Tammy still experiences some level of emotional expression.'
0:16:44 > 0:16:48She said it's very kind of elementary in a way.
0:16:48 > 0:16:50And it's not linked into the logical system.
0:16:50 > 0:16:53I don't understand what the difference is of all these things.
0:16:53 > 0:16:56Right, if I forget things, I'll get my husband to pick 'em up...
0:16:56 > 0:17:01Eslinger wants to see how Tammy copes with the most basic choices.
0:17:01 > 0:17:03What should she buy for dinner?
0:17:03 > 0:17:05So here you have some choices.
0:17:05 > 0:17:08How do you decide what it is you would like?
0:17:08 > 0:17:13Um...I just look at different things that are here.
0:17:13 > 0:17:18And the different prices. I don't want baked potatoes.
0:17:18 > 0:17:20I'd probably just pick up a bag of...
0:17:21 > 0:17:25..maybe the gold potatoes, or...
0:17:25 > 0:17:29'She was taking in the information accurately about what she was seeing
0:17:29 > 0:17:33'and the fact there was cost and size and colour.'
0:17:33 > 0:17:37So her brain was processing all the logical information, but the
0:17:37 > 0:17:43emotion system wasn't coming into play, linking to that logic system.
0:17:43 > 0:17:47There's so many. Why do you need so many potatoes?
0:17:47 > 0:17:51- Ha! My chest is all tight thinking about all this.- Why is that?
0:17:51 > 0:17:54Because it's stress. It's a decision.
0:17:54 > 0:17:56It's...it's, um...
0:17:56 > 0:17:58There's a lot of stuff laying here.
0:17:59 > 0:18:02'Tammy quickly became overwhelmed with information
0:18:02 > 0:18:04'that she couldn't prioritise.'
0:18:05 > 0:18:07The route that she took was,
0:18:07 > 0:18:09"Let me take that one and get out of here".
0:18:09 > 0:18:11I can't process the information.
0:18:11 > 0:18:14- It's too much.- Now, was that true before your accident?
0:18:14 > 0:18:17No, no. I was an engineer.
0:18:17 > 0:18:20I could do everything. But now I can't.
0:18:20 > 0:18:22I can't pick a ham, let alone make ten decisions at work
0:18:22 > 0:18:25within the next hour. Ten decisions maybe in the week.
0:18:28 > 0:18:31The situation makes Tammy stressed,
0:18:31 > 0:18:34but she can't make herself care about her choices.
0:18:35 > 0:18:36To make a decision,
0:18:36 > 0:18:40she needs to somehow value one option over another.
0:18:40 > 0:18:43That's a lot of information to process.
0:18:45 > 0:18:49And that can only be done with the help of the emotions.
0:18:49 > 0:18:51It's information that you have to put into your head...
0:18:51 > 0:18:54'The logical brain system still is very strong.
0:18:54 > 0:18:58'And we want to force it to tap into the emotion system.'
0:18:58 > 0:18:59So one of the things we do day-to-day
0:18:59 > 0:19:02is we discard things that are not so important.
0:19:02 > 0:19:06And sometimes it's our emotions that help us do that separation.
0:19:06 > 0:19:09By having that logical brain system work on the process,
0:19:09 > 0:19:11we may be able to break through,
0:19:11 > 0:19:14at least in some ways, to reconnect those.
0:19:18 > 0:19:21'I don't know what tomorrow is. Am I going to be better?
0:19:21 > 0:19:23'Am I going to be worse?'
0:19:23 > 0:19:27It seems like the pieces of the puzzle could be coming
0:19:27 > 0:19:29together in a gradual fashion,
0:19:29 > 0:19:35but it's really slow as far as my past being would have accepted.
0:19:38 > 0:19:43'Tammy's story shows how important emotions are in making decisions.
0:19:45 > 0:19:51'But here's the thing - emotions don't just happen inside the brain.
0:19:51 > 0:19:55'Our emotional systems interact with the rest of our physiology.
0:19:57 > 0:20:03'When we're faced with choices, our muscles imperceptibly tense.
0:20:03 > 0:20:06'Our hormone levels fluctuate.
0:20:06 > 0:20:10'These are automatic physical reactions.
0:20:10 > 0:20:12'Gut feelings. And we need them.'
0:20:14 > 0:20:16I'm trying to decide what kind of soup I want,
0:20:16 > 0:20:18but it's a really difficult choice.
0:20:18 > 0:20:21There's so many details for my brain to compute.
0:20:21 > 0:20:25There's calories and price and taste and salt and packaging.
0:20:25 > 0:20:28There are a millions details here
0:20:28 > 0:20:32and I'm going to be paralysed all day under this mountain of data.
0:20:32 > 0:20:35So what I really need is some sort of summary, a quick read.
0:20:35 > 0:20:39And that's what the physiologic states of my body give me.
0:20:39 > 0:20:43It allows me to put a value on this choice and a value on that choice.
0:20:43 > 0:20:46And that's what allows me to make the decision.
0:20:54 > 0:20:57'This conversation between the body and the brain never stops.
0:20:59 > 0:21:03'But it really comes to the fore when we're stressed, or in danger.
0:21:11 > 0:21:13'Take this situation.
0:21:14 > 0:21:19'Before I think rationally about what's going on, I react physically.
0:21:23 > 0:21:25'My sweat glands open.
0:21:27 > 0:21:29'My heart rate increases.
0:21:31 > 0:21:35'My pupils dilate. My body's screaming a simple message.
0:21:37 > 0:21:39'Get me out of here!'
0:21:43 > 0:21:46Every day, we experience emotional states like this,
0:21:46 > 0:21:49but because they're mostly subtle and unconscious,
0:21:49 > 0:21:51we're not typically aware of them.
0:21:51 > 0:21:54But it turns out these states are crucial for navigating
0:21:54 > 0:21:56all the decisions in our life.
0:22:03 > 0:22:08'Most of us tend to distrust decisions based on feelings
0:22:08 > 0:22:09'rather than intellect.
0:22:11 > 0:22:15'So it can be surprising to learn just how much insight
0:22:15 > 0:22:17'feelings can give us.'
0:22:22 > 0:22:26Richard Tunney is an experimental psychologist.
0:22:26 > 0:22:29He studies the formation of unconscious decisions.
0:22:34 > 0:22:39He's running an experiment known as the Iowa Gambling Task.
0:22:39 > 0:22:41I need you to keep your hands still.
0:22:41 > 0:22:44Because that will affect the measurements we make.
0:22:48 > 0:22:52A volunteer chooses to draw a card from one of four decks.
0:22:56 > 0:23:00Each time she draws a card, she wins some amount of money
0:23:00 > 0:23:01and she loses some.
0:23:04 > 0:23:07Her task is to earn as much as possible.
0:23:10 > 0:23:15As she plays, she's hooked up a machine similar to a lie-detector.
0:23:15 > 0:23:19It monitors tiny changes in the sweat glands in her skin.
0:23:24 > 0:23:29What she doesn't know is that the decks are not random, but rigged.
0:23:31 > 0:23:34If she keeps choosing from decks A and C,
0:23:34 > 0:23:36she'll end up making the most money.
0:23:40 > 0:23:44The question is, how long before she figures that out?
0:23:46 > 0:23:51The participant will explore the decks in the first instance
0:23:51 > 0:23:54and they'll choose from all four decks.
0:23:54 > 0:23:58They don't really begin to choose from the good decks consciously
0:23:58 > 0:24:00until in the region of 20-30 cards.
0:24:03 > 0:24:05But here's the thing -
0:24:05 > 0:24:08the monitor indicates that volunteers figure out
0:24:08 > 0:24:12which decks are good and bad much earlier.
0:24:12 > 0:24:17After only ten tries, there's a spike of activity,
0:24:17 > 0:24:21a warning sign whenever she reaches for the bad decks.
0:24:23 > 0:24:27She doesn't realise it, but that's the beginnings of a hunch,
0:24:27 > 0:24:32an understanding that her body registers before her conscious mind.
0:24:32 > 0:24:35What we're seeing here is we're seeing
0:24:35 > 0:24:41some physiological response prior to making the decision.
0:24:41 > 0:24:45This spike here, in effect, predicts the choice
0:24:45 > 0:24:48the participant is going to make.
0:24:50 > 0:24:54As her hunch grows stronger, she marries logic
0:24:54 > 0:24:56to what her body's been telling her.
0:24:56 > 0:24:59Which decks to draw from and which to avoid.
0:25:04 > 0:25:06OK, can I stop you there for a moment?
0:25:06 > 0:25:11Can I ask you, if you were to choose any one of those four decks
0:25:11 > 0:25:14for the rest of the experiment, which one would you choose?
0:25:16 > 0:25:18I think I would choose deck C.
0:25:18 > 0:25:20OK. Carry on.
0:25:20 > 0:25:23It may feel like a logical deduction,
0:25:23 > 0:25:27but it's built on a physical foundation.
0:25:29 > 0:25:32The body and the brain are all integral to one another.
0:25:32 > 0:25:35It's all part of the same system.
0:25:39 > 0:25:42If physiology always plays a part in our decision-making,
0:25:42 > 0:25:44what does that say about us?
0:25:45 > 0:25:48Do we ever act in a purely rational way?
0:25:48 > 0:25:52Or is that simply an illusion that we cling to?
0:25:55 > 0:25:57Well, consider this -
0:25:57 > 0:26:01if you ever come before a parole board, keep an eye on the clock.
0:26:02 > 0:26:06We would all hope that Lady Justice is impartial,
0:26:06 > 0:26:10but studies say otherwise, in a way that might surprise you.
0:26:11 > 0:26:16Two men come up for parole on the same day, but three hours apart.
0:26:16 > 0:26:19They've committed the same offence and served the same sentence.
0:26:19 > 0:26:22So, what does the judge decide?
0:26:26 > 0:26:28Now, here's what happened.
0:26:28 > 0:26:32The first prisoner was granted parole and the second was denied.
0:26:32 > 0:26:37Why? Given the crime was the same, what influenced the decision?
0:26:37 > 0:26:41Was it race, age, looks?
0:26:41 > 0:26:45Well, one study analysed 1,000 rulings from different judges
0:26:45 > 0:26:49and they found it wasn't about those factors, it was about this.
0:26:54 > 0:26:56'According to the research,
0:26:56 > 0:26:59'prisoners were three times more likely to be given parole
0:26:59 > 0:27:03'just after lunch, when board members were well fed,
0:27:03 > 0:27:06'than just before lunch, when they were feeling hungry.
0:27:08 > 0:27:13'Having to make decisions all morning is mentally taxing.
0:27:13 > 0:27:17'And the judges were suffering from what's known as ego depletion.'
0:27:20 > 0:27:25Their brains were running low on energy and that especially affects
0:27:25 > 0:27:29the prefrontal cortex, which is involved in decision-making.
0:27:30 > 0:27:33Traditionally, we assume humans are rational decision-makers.
0:27:33 > 0:27:37They take in information, process it and come up with the best answer.
0:27:37 > 0:27:41But real humans, even judges, don't operate that way.
0:27:41 > 0:27:43They're biological creatures.
0:27:46 > 0:27:50'The court system sets out to be rational and balanced,
0:27:50 > 0:27:52'so it's a disturbing thought that it can be hijacked
0:27:52 > 0:27:55'by the basic chemistry of our bodies.
0:27:56 > 0:28:00'Even judges can be imprisoned by their biology.'
0:28:07 > 0:28:10The story's the same with some of life's other big choices.
0:28:12 > 0:28:16Where the decisions we make aren't necessarily conscious ones.
0:28:16 > 0:28:21Instead, we're tugged along by hidden biological forces.
0:28:24 > 0:28:28Evolutionary psychologist Geoffrey Miller has come up with
0:28:28 > 0:28:30an interesting way to show this.
0:28:37 > 0:28:42His team recruited the help of 18 lap dancers in New Mexico
0:28:42 > 0:28:46and got them to record their earnings over three months.
0:28:49 > 0:28:53We know that lap dancers' earnings fluctuate a lot.
0:28:54 > 0:28:58Some nights, they earn 800.
0:28:58 > 0:29:01Other nights, they might earn only 150.
0:29:01 > 0:29:04And they're very conscious of how much they earn.
0:29:04 > 0:29:08So it seemed like an ideal set-up for being able to ask them,
0:29:08 > 0:29:12"How much have you earned night by night, shift by shift?"
0:29:12 > 0:29:14And to be able to track that in relation to
0:29:14 > 0:29:17where they are in the menstrual cycle.
0:29:19 > 0:29:22Miller wanted to know if a woman becomes more attractive
0:29:22 > 0:29:25to a man when she's ovulating.
0:29:25 > 0:29:29At that point in her cycle, when she's most fertile,
0:29:29 > 0:29:34a surge of the hormone oestrogen makes her skin softer,
0:29:34 > 0:29:37her features more symmetrical
0:29:37 > 0:29:39and her hip-to-waist ratio larger.
0:29:41 > 0:29:42The changes are subtle,
0:29:42 > 0:29:47but men's brains pick up on those cues unconsciously.
0:29:48 > 0:29:51The results were surprisingly strong.
0:29:51 > 0:29:54When women are ovulating,
0:29:54 > 0:29:57they're earning about twice as much as they were earning
0:29:57 > 0:29:59when they were menstruating,
0:29:59 > 0:30:02but they were also earning a lot more than before menstruation.
0:30:04 > 0:30:06So the real pattern is, if you're ovulating,
0:30:06 > 0:30:10you're a lot more attractive to men, you're earning higher tips,
0:30:10 > 0:30:14you're getting called over for more lap dances.
0:30:14 > 0:30:18And we thought that was a pretty cool way of quantifying
0:30:18 > 0:30:20female attractiveness to males.
0:30:28 > 0:30:33Your hidden biological drives help you to select a partner.
0:30:37 > 0:30:41But what makes you choose to stay with a partner?
0:30:43 > 0:30:46It must have something to do with your values and your morals, right?
0:30:46 > 0:30:51Actually, your hormones are doing a lot of the deciding for you.
0:30:51 > 0:30:54One of them is this. It's called oxytocin.
0:30:57 > 0:30:59Sometimes called the love hormone,
0:30:59 > 0:31:05oxytocin strengthens the bonds we feel when we're in a relationship.
0:31:05 > 0:31:07In a recent study,
0:31:07 > 0:31:11heterosexual men who were in love were given a dose of oxytocin.
0:31:13 > 0:31:17They were then asked to rate the attractiveness of different women.
0:31:21 > 0:31:23The men who were given oxytocin
0:31:23 > 0:31:27found their partners to be more attractive, but not other women.
0:31:27 > 0:31:28In fact, with other women,
0:31:28 > 0:31:31they kept a slightly greater physical distance.
0:31:33 > 0:31:36So an attractive woman walks into the bar.
0:31:41 > 0:31:44Lots of men clock her arrival.
0:31:48 > 0:31:50But not this guy.
0:31:50 > 0:31:52He's in love with his partner
0:31:52 > 0:31:57and, pumped up with oxytocin, his attention doesn't wander.
0:32:01 > 0:32:03From an evolutionary perspective,
0:32:03 > 0:32:06you might expect that you don't want monogamy,
0:32:06 > 0:32:08you want to have as many offspring as possible.
0:32:08 > 0:32:12So, why do we have chemicals in the brain that enhance bonding?
0:32:12 > 0:32:14Well, for the survival of the children,
0:32:14 > 0:32:17having two parents around is better than having one.
0:32:17 > 0:32:22It's so important that our brains make this decision for us.
0:32:34 > 0:32:39In fact, the evidence suggests that some of our most complex decisions,
0:32:39 > 0:32:43the ones we like to think of as carefully thought out,
0:32:43 > 0:32:46are pre-programmed, influenced by our DNA.
0:32:47 > 0:32:50Almost no choice at all.
0:32:50 > 0:32:54If you feel the least bit uncomfortable, squeeze the squeeze ball
0:32:54 > 0:32:57and we'll stop and take you out.
0:32:57 > 0:33:04Read Montague uses neuroscience to analyse and predict voting patterns.
0:33:04 > 0:33:06CHEERING AND APPLAUSE
0:33:10 > 0:33:15It turns out that political ideology has strong biological underpinnings
0:33:15 > 0:33:18which you can inherit from your parents.
0:33:21 > 0:33:25Montague has found a link between a person's politics
0:33:25 > 0:33:28and one basic reaction, disgust.
0:33:31 > 0:33:34He has volunteers go into an MRI scanner,
0:33:34 > 0:33:37where they look at a series of images.
0:33:39 > 0:33:42I show them somebody with a knife to somebody else's throat,
0:33:42 > 0:33:46physically threatening stimulus. A dead corpse.
0:33:46 > 0:33:49Something that was gross, like flies on a salad,
0:33:49 > 0:33:51or something like this.
0:33:51 > 0:33:54These things elicit responses in your nervous system
0:33:54 > 0:33:56and we record their brain activity.
0:33:59 > 0:34:01Then we asked them, and not everybody agrees,
0:34:01 > 0:34:04we asked them, "Hey, we have this other experiment we want you to do".
0:34:04 > 0:34:10And they go into a booth and they answer a political ideology survey.
0:34:10 > 0:34:12How do you feel about gun control,
0:34:12 > 0:34:16abortion, premarital sex, things like that.
0:34:21 > 0:34:23Montague's results are striking.
0:34:25 > 0:34:28The greater the disgust response in the brain,
0:34:28 > 0:34:30the more conservative the person is likely to be.
0:34:32 > 0:34:36A smaller response correlates with a more liberal outlook.
0:34:39 > 0:34:41The link between your neural response
0:34:41 > 0:34:46and your political affiliation is not conscious, but it's powerful.
0:34:46 > 0:34:50I think if you ask nine out of ten people on the street,
0:34:50 > 0:34:53"How did you decide to vote for Candidate X?"
0:34:53 > 0:34:56They would give you a long narrative about what they cared about,
0:34:56 > 0:35:00the issues that Candidate X supported,
0:35:00 > 0:35:02which side of those issues you were on
0:35:02 > 0:35:04and how that person represented them.
0:35:04 > 0:35:07But that is only half the story.
0:35:07 > 0:35:12The shocking part is that your response
0:35:12 > 0:35:14to a single disgusting image
0:35:14 > 0:35:18can predict your score on that test
0:35:18 > 0:35:20with 95% accuracy.
0:35:22 > 0:35:25That kind of prediction is uncanny.
0:35:25 > 0:35:27I show you a disgusting image,
0:35:27 > 0:35:29I know how you're going to vote in 2016.
0:35:31 > 0:35:33We may refine our political arguments,
0:35:33 > 0:35:35they may become more sophisticated,
0:35:35 > 0:35:41but the decision about our basic persuasion, that's already made.
0:35:45 > 0:35:48'So far, we've been looking at decisions in the here and now.
0:35:51 > 0:35:53'What soup do I want?
0:35:53 > 0:35:55'Do I pull the lever?
0:35:55 > 0:35:57'Who do I vote for?'
0:35:57 > 0:35:59Orange. Green.
0:36:02 > 0:36:06'But there's another aspect to the story of decisions.
0:36:06 > 0:36:08'Predictions about the future.
0:36:08 > 0:36:11'We have to weigh different options
0:36:11 > 0:36:13'and guess how things might turn out
0:36:13 > 0:36:15'at a time that doesn't yet exist.
0:36:17 > 0:36:20'How does your brain pull off that trick?'
0:36:20 > 0:36:25I have one hour of free time today and I'm trying to decide what to do.
0:36:25 > 0:36:28I know I have to get to the grocery store, on the other hand,
0:36:28 > 0:36:31I need to get to a coffee shop to work on a grant deadline.
0:36:31 > 0:36:35And I'd like to be able to play with my son at the park today.
0:36:35 > 0:36:37So, how do I decide?
0:36:37 > 0:36:40Well, ideally, I'd like to be able to know what each of these
0:36:40 > 0:36:44possible futures would be like, but I can't time-travel.
0:36:44 > 0:36:46Or can I?
0:36:48 > 0:36:52'It may sound like the plot of a movie, but wouldn't it be great
0:36:52 > 0:36:56'if we could make decisions by looking back from the future?
0:37:02 > 0:37:06'That's exactly what our brains are trying to do all the time.
0:37:07 > 0:37:10'Running simulations of the future
0:37:10 > 0:37:13'and giving each of them a different value.'
0:37:17 > 0:37:20Think of valuations like neural price tags that tell us
0:37:20 > 0:37:23how much we think something's going to be worth.
0:37:24 > 0:37:27So going grocery shopping will put food in my fridge,
0:37:27 > 0:37:30but, say that's worth ten units to me.
0:37:30 > 0:37:32Writing a grant will fund my lab,
0:37:32 > 0:37:35but it's difficult, let's say that's 25 units.
0:37:37 > 0:37:40I love spending time with my son at the park,
0:37:40 > 0:37:41so let's say that's 50 units.
0:37:43 > 0:37:47Here's the thing - those prices can change through time.
0:37:48 > 0:37:52If we get there, we run into friends and it's better than expected,
0:37:52 > 0:37:55that ups my price tag for the next time around.
0:37:55 > 0:37:59If we get there and the swings are broken and it's raining,
0:37:59 > 0:38:02that lowers my price tag for the next time.
0:38:03 > 0:38:04And that's important.
0:38:04 > 0:38:09That's what allows us to prioritise how we make our decisions
0:38:09 > 0:38:12based on the brain's best guesses for the future.
0:38:17 > 0:38:21And it turns out there's a tiny, ancient system in the brain
0:38:21 > 0:38:24whose whole job is to keep updating our assessments of the world.
0:38:28 > 0:38:30I'm talking about the dopamine system.
0:38:32 > 0:38:36The chemical dopamine typically has a constant rate of release.
0:38:36 > 0:38:39But when something turns out better than expected,
0:38:39 > 0:38:42there's a burst of dopamine.
0:38:42 > 0:38:44That tells other parts of the brain
0:38:44 > 0:38:48they should increase the value of that option.
0:38:48 > 0:38:52When something is worse than expected, the dopamine drops
0:38:52 > 0:38:54and the value goes down.
0:38:56 > 0:38:59In most of us, this system works pretty well,
0:38:59 > 0:39:01but it's delicately balanced.
0:39:01 > 0:39:05Too much dopamine and that loop of positive feedback
0:39:05 > 0:39:07gets out of control.
0:39:07 > 0:39:09This is the root of addiction.
0:39:12 > 0:39:17Neural psychiatrist Valerie Voon studies addictive behaviour.
0:39:18 > 0:39:21She's interested in patients with Parkinson's disease.
0:39:23 > 0:39:26They're producing less dopamine than normal,
0:39:26 > 0:39:30so they're routinely put on medication to raise their levels.
0:39:32 > 0:39:35What happens with dopamine medications that the patient
0:39:35 > 0:39:39with Parkinson's is on is that it can potentially hijack the system.
0:39:42 > 0:39:46Patients who were previously moderate in their behaviour
0:39:46 > 0:39:51suddenly develop addictions to gambling, or food, or sex.
0:39:54 > 0:39:59These dopamine-stimulating drugs are overstimulating the regions
0:39:59 > 0:40:02involved in reward and motivation.
0:40:02 > 0:40:05You see the cue and your expectation of the reward
0:40:05 > 0:40:08becomes much larger than it should be.
0:40:13 > 0:40:17When you take the medication away, they're always a bit dumbfounded
0:40:17 > 0:40:21about how they ended up acting the way they did.
0:40:22 > 0:40:25'As long as there's nothing wrong with our dopamine systems,
0:40:25 > 0:40:29'it should be straightforward for us to control our impulses, right?
0:40:30 > 0:40:32'Don't be so sure.
0:40:35 > 0:40:39'Take the subprime mortgage meltdown of 2007.
0:40:39 > 0:40:42'Between bankers hunting a quick profit
0:40:42 > 0:40:46'and borrowers hunting their too-good-to-be-true dream homes,
0:40:46 > 0:40:51'it turned into a storm of disastrous decisions.
0:40:52 > 0:40:55'As a neuroscientist, what fascinates me
0:40:55 > 0:40:59'is how everyone involved gave less weight to future consequences
0:40:59 > 0:41:05'and were instead seduced by what was right in front of them.'
0:41:06 > 0:41:10The very low interest rates plugged right into the
0:41:10 > 0:41:12"I want it now" circuitry.
0:41:12 > 0:41:15The idea is, take this house right now,
0:41:15 > 0:41:18live better than you thought you could.
0:41:18 > 0:41:21At some point in the future, the interest rates will go up,
0:41:21 > 0:41:23but that's a long way away.
0:41:23 > 0:41:26Because the pull of the now is so hard to resist,
0:41:26 > 0:41:29the world economy almost tanked.
0:41:35 > 0:41:37This present moment is a rich,
0:41:37 > 0:41:42multisensory experience that's hitting me right now.
0:41:42 > 0:41:45But the future, that's just an idea.
0:41:45 > 0:41:48That's a simulation that takes place in my neural circuits
0:41:48 > 0:41:52and it's a pale shadow compared to immediate experience.
0:41:52 > 0:41:57It has less emotional pull than whatever is right in front of me.
0:42:05 > 0:42:08So, once again, the brain is in conflict.
0:42:08 > 0:42:12Different networks are battling it out between the present
0:42:12 > 0:42:14and the future.
0:42:14 > 0:42:16Instant gratification?
0:42:16 > 0:42:18Or long-term reward?
0:42:22 > 0:42:26When faced with these sorts of decisions, what do we do?
0:42:26 > 0:42:30We rely on our willpower.
0:42:30 > 0:42:34Think of willpower as that thing that allows you to pass on that cookie,
0:42:34 > 0:42:35or at least the second cookie!
0:42:35 > 0:42:40Or the thing that allows you to hit that deadline even though you want to be out in the sunshine.
0:42:40 > 0:42:44We all know what it's like to have strong willpower and we also
0:42:44 > 0:42:47know what it feels like when you just don't have enough of it.
0:42:51 > 0:42:57In one experiment, people watch a wildlife film about animals in distress.
0:43:01 > 0:43:04Half the audience has been told to react normally,
0:43:04 > 0:43:06to cry if they feel like it.
0:43:10 > 0:43:14The other half are instructed to curb their emotions,
0:43:14 > 0:43:17using their willpower to squelch their feelings.
0:43:22 > 0:43:25The key is what happens next.
0:43:30 > 0:43:35After the movie, participants were given one of these - a hand exerciser -
0:43:35 > 0:43:38and they were asked to squeeze it as long as they could.
0:43:47 > 0:43:53The people who curbed their emotions give up squeezing sooner than the others.
0:43:55 > 0:43:59They've exerted so much mental effort not to cry,
0:43:59 > 0:44:03they actually have reduced physical strength.
0:44:05 > 0:44:08This kind of self control, it takes energy.
0:44:10 > 0:44:13It turns out that resisting temptation, or making hard decisions
0:44:13 > 0:44:19or taking initiative - all of these draw from the same well of energy.
0:44:19 > 0:44:21So, willpower isn't something that we exercise,
0:44:21 > 0:44:23it's something that we use up.
0:44:23 > 0:44:26It's like a tank of gas.
0:44:28 > 0:44:32So, there's a good reason why we can't always rely on our willpower
0:44:32 > 0:44:35to make us stand by our decisions.
0:44:35 > 0:44:38Our willpower might be running on empty.
0:44:42 > 0:44:45We all know that it's hard to get ourselves to do certain things,
0:44:45 > 0:44:47like going to the gym.
0:44:47 > 0:44:50I want to be in shape, but when it comes down to it,
0:44:50 > 0:44:53there's usually something going on right in front of me that's more enjoyable.
0:44:53 > 0:44:56So, the pull of what's happening right then
0:44:56 > 0:45:01is more powerful than the abstract future notion of fitness.
0:45:01 > 0:45:03So, to make certain that I come here,
0:45:03 > 0:45:07I take inspiration from a man who lived 3,000 years ago.
0:45:11 > 0:45:16In classical mythology, the hero Ulysses lashed himself to the
0:45:16 > 0:45:21mast of his ship so that he could hear the bewitching song
0:45:21 > 0:45:25of the sirens without steering into the rocks.
0:45:29 > 0:45:32Ulysses knew that his future self wasn't going to be in any
0:45:32 > 0:45:34position to make a good decision.
0:45:34 > 0:45:38So, he structured things so that he couldn't do the wrong thing.
0:45:38 > 0:45:41This sort of deal that's struck between your present
0:45:41 > 0:45:45and your future self is known as the Ulysses contract.
0:45:45 > 0:45:48My own Ulysses contract is to arrange with a friend to meet me here
0:45:48 > 0:45:53at the gym, and that way the social pressure lashes me to the mast.
0:45:57 > 0:46:02My friendship is collateral in the deal that I'm making with my future self.
0:46:03 > 0:46:07This allows me to be the person I want to be,
0:46:07 > 0:46:12making good decisions, resisting the seductive power of now.
0:46:16 > 0:46:19- Come on.- I got it.
0:46:19 > 0:46:22Oh, yeah. Nice.
0:46:22 > 0:46:26Our prisons are full of people who struggle with this.
0:46:26 > 0:46:30They're unable to lash themselves to any mast
0:46:30 > 0:46:32to avoid the rocks.
0:46:34 > 0:46:36Attention, there is a door alarm.
0:46:36 > 0:46:39For seven out of ten prisoners jailed in the US,
0:46:39 > 0:46:44their ability to make long-term decisions is compromised.
0:46:44 > 0:46:47They are there because of drugs.
0:46:50 > 0:46:54For four decades, we have waged a war on drugs.
0:46:54 > 0:46:59The US invests 20 billion each year into this fight.
0:47:00 > 0:47:02But there's no sign of victory.
0:47:02 > 0:47:06'And destroying the crop before the opium could be harvested from it.'
0:47:06 > 0:47:10The difficulty with drug supply is that it's like a water balloon.
0:47:10 > 0:47:13If you press it down in one place, it will come up somewhere else.
0:47:13 > 0:47:18So, instead of attacking supply, a better strategy is to address demand -
0:47:18 > 0:47:22and demand is in the brain of the addict.
0:47:25 > 0:47:30So, if the problems lie in the brain, maybe the solutions do, too.
0:47:39 > 0:47:43A couple of miles from my laboratory, there's a crack house.
0:47:48 > 0:47:53It's abandoned now, but this was once a regular hang-out for Karen.
0:47:58 > 0:48:00It brings tears to my eyes.
0:48:00 > 0:48:05Because this was part of the lowest part I hit when I smoked crack.
0:48:07 > 0:48:09And I can't believe that I was part of that crowd.
0:48:12 > 0:48:14If you're not strong enough, you just can't handle it.
0:48:14 > 0:48:16It kind of draws you in.
0:48:21 > 0:48:25Karen has had an addiction to crack cocaine for many years.
0:48:28 > 0:48:31I thought I was in control of everything.
0:48:31 > 0:48:34But that was the drug. I mean, I wasn't in control of anything.
0:48:34 > 0:48:36I was a mess.
0:48:36 > 0:48:42Dirty, hair matted up, clothes looked like they were in a mud fight -
0:48:42 > 0:48:45I couldn't believe it. And then I'd step back and think,
0:48:45 > 0:48:47"Damn! How did I drop so low?"
0:48:54 > 0:48:58Karen's story makes her an ideal candidate for a new programme
0:48:58 > 0:49:00we're running in my laboratory.
0:49:03 > 0:49:06Rather than simply forcing drug addicts to go cold turkey,
0:49:06 > 0:49:10we're trying to treat them with neuroscience.
0:49:13 > 0:49:17Getting the brain to take control of its own addiction.
0:49:21 > 0:49:25Inside the MRI machine, Karen watches images of drug use
0:49:25 > 0:49:28and drug paraphernalia.
0:49:28 > 0:49:32We ask her to go ahead and feel her cravings.
0:49:35 > 0:49:39We measured the networks in her brain associated with that craving.
0:49:46 > 0:49:51Then we switch and ask her to suppress the craving.
0:49:52 > 0:49:56OK, Karen, when you're thinking about suppressing your craving,
0:49:56 > 0:50:00think about the costs this has had to you - in terms of money,
0:50:00 > 0:50:05in terms of relationship, in terms of employment opportunities.
0:50:05 > 0:50:07'OK.'
0:50:09 > 0:50:13We show her the same images and measure the regions in her brain
0:50:13 > 0:50:17that are active when she's trying to resist the desire to use.
0:50:19 > 0:50:24These are the networks that become active in Karen's brain when she's craving cocaine,
0:50:24 > 0:50:30and when she thinks about all the reasons to resist it, then these networks come online here.
0:50:30 > 0:50:33And these networks, the craving and the suppressing,
0:50:33 > 0:50:35are always locked in battle.
0:50:37 > 0:50:41Here's the key - we now superimpose a gauge,
0:50:41 > 0:50:45which tells Karen how the battle is going.
0:50:45 > 0:50:49Her job is to move it by tipping the balance
0:50:49 > 0:50:53of the suppressing over the craving.
0:50:53 > 0:50:58They show you pictures of different things. You have to do suppress and then not suppress.
0:50:58 > 0:50:59It was like a little meter.
0:50:59 > 0:51:02When it got to the first time, I couldn't do it at all.
0:51:02 > 0:51:06Then, the second time, I got wind of it and I could really concentrate and say,
0:51:06 > 0:51:09"Hey, this is it! This is what I've been missing.
0:51:09 > 0:51:13"Your brain is the one that told you you needed crack,
0:51:13 > 0:51:16"so why can't you train your brain to tell you it's not time for crack?"
0:51:18 > 0:51:21I mean, I can suppress other things, why can't I suppress crack?
0:51:23 > 0:51:27At the moment, she's looking at this background picture of cocaine
0:51:27 > 0:51:31and she is working her way over to suppressing that craving
0:51:31 > 0:51:33and holding it there successfully.
0:51:33 > 0:51:38Now, the idea is that she can practice this in the scanner and learn how to get better at it
0:51:38 > 0:51:44and the key is when she's back out in the real world and somebody offers her crack cocaine,
0:51:44 > 0:51:49she'll have the tools available to know how to resist.
0:51:49 > 0:51:52I'm not going to say I'm cured, because how can you be cured
0:51:52 > 0:51:56of something that your brain conjures up - your subconscious conjures up.
0:51:56 > 0:52:00So, I take steps to, when the thought goes through, I push it out.
0:52:00 > 0:52:02I suppress it.
0:52:02 > 0:52:06You know, I'm not going to say three months from now, a year from now, I'll be clean,
0:52:06 > 0:52:08but that's what I work towards daily.
0:52:12 > 0:52:16For me, Karen offers a glimpse of how neuroscience
0:52:16 > 0:52:19can help people with addiction.
0:52:19 > 0:52:24She's rewiring her circuitry, she's shaping her brain
0:52:24 > 0:52:29to be better aligned with who she would like to be.
0:52:29 > 0:52:32The future is filled with promise.
0:52:32 > 0:52:37I'm married, I have a great husband, I have a great life
0:52:37 > 0:52:41and I don't want to jeopardise that just for a hit of crack.
0:52:41 > 0:52:45So, I mean, it's even more of a reason why I quit crack.
0:52:45 > 0:52:50It helps my suppression state, because I can actually stop
0:52:50 > 0:52:53and I'm doing it for myself, but I'm doing it for others.
0:52:53 > 0:52:58My husband, my dogs, my family and that's what's important to me.
0:53:02 > 0:53:07Karen has hope for resolving the conflict that constantly rages
0:53:07 > 0:53:10in the hidden world of her neural networks.
0:53:13 > 0:53:16I think a biological approach stands a better chance
0:53:16 > 0:53:19of working than mass incarceration.
0:53:21 > 0:53:24As we learn more about our own brains,
0:53:24 > 0:53:28we can break away from slavery to our impulses
0:53:28 > 0:53:32and earn the freedom that comes with having greater choice.
0:53:34 > 0:53:37Decision-making lies at the heart of everything -
0:53:37 > 0:53:41who we are, what we do, how we perceive the world.
0:53:41 > 0:53:43Without the ability to decide,
0:53:43 > 0:53:47we would be stuck in limbo between conflicting desires.
0:53:47 > 0:53:51We wouldn't be able to navigate the now or plan for the future.
0:53:51 > 0:53:54Neuroscience shows that you are not an individual,
0:53:54 > 0:53:58you're made up of multiple competing drives.
0:53:58 > 0:54:02And by understanding how choices battle it out in the brain,
0:54:02 > 0:54:07we can learn how to make better decisions for ourselves and for society.
0:54:10 > 0:54:12CROWD CHEERS AND APPLAUDS
0:54:15 > 0:54:19Next time on The Brain, I'm going to investigate how our brains
0:54:19 > 0:54:22are fundamentally wired to work together.
0:54:22 > 0:54:26How this social network that envelops us from birth
0:54:26 > 0:54:29is vital for our survival.
0:54:30 > 0:54:33Understanding how brains deal with each other
0:54:33 > 0:54:37allows us to understand what bonds our species...
0:54:39 > 0:54:42..driving us to help one another.
0:54:42 > 0:54:45And what makes us hate.
0:54:46 > 0:54:49What allows acts of human violence.
0:54:51 > 0:54:55Here, in 1995, thousands of Bosniaks took refuge
0:54:55 > 0:54:58inside this United Nations compound.
0:54:58 > 0:55:02But then on July 11th, the UN commanders made the decision
0:55:02 > 0:55:06to expel all the refugees and they delivered them right into the hands
0:55:06 > 0:55:10of their enemies who were waiting just outside this gate.
0:55:10 > 0:55:13Even the most basic encounter...
0:55:13 > 0:55:15like getting a cup of coffee...
0:55:15 > 0:55:18..relies on trust with a stranger.
0:55:18 > 0:55:20- Can I get a latte, please? - Definitely.- Thanks.
0:55:22 > 0:55:25Our lives are built on these intersections.
0:55:25 > 0:55:28It helps us to make sense of our past
0:55:28 > 0:55:31and holds the key to our future.