0:00:06 > 0:00:10Welcome to the strange and wonderful world of illusions.
0:00:10 > 0:00:12Baa. Baa. Baa.
0:00:12 > 0:00:16Illusions to deceive your eyes.
0:00:16 > 0:00:18So I do take cheques.
0:00:18 > 0:00:20Trick your tongue.
0:00:22 > 0:00:26And fool your sense of touch.
0:00:26 > 0:00:29Oh!
0:00:29 > 0:00:36But don't worry, it's all in the name of a noble scientific quest.
0:00:36 > 0:00:40These illusions hold the key to how our senses work.
0:00:40 > 0:00:42When you open your eyes in the morning,
0:00:42 > 0:00:45most people think, "I'm seeing the world as it is".
0:00:45 > 0:00:49The beautiful thing about illusions is they tell us that that's not true.
0:00:49 > 0:00:53They show us that our perceptions of the world are something different
0:00:53 > 0:00:55from seeing it as it really is.
0:00:58 > 0:01:03Illusions are providing a unique window into the inner workings of our minds.
0:01:03 > 0:01:08Helping to reveal what our sensory brains are really capable of.
0:01:08 > 0:01:11So this is a golden age in perceptual psychology.
0:01:11 > 0:01:15The things we've learned over the last ten years have been absolutely phenomenal.
0:01:15 > 0:01:20These new discoveries are opening up a whole new world of possibility.
0:01:20 > 0:01:26Even enabling us to move beyond our sensory evolution altogether.
0:01:31 > 0:01:37So watch, play along, and prepare to be amazed at what your senses can do.
0:01:51 > 0:01:55Can you trust anything you see with your eyes?
0:01:57 > 0:02:00Do you think seeing is really believing?
0:02:02 > 0:02:06The beautiful thing about illusions is that they make us realise
0:02:06 > 0:02:09things are not always quite as they seem.
0:02:12 > 0:02:17So the question for you is, you see the surface here and the surface there?
0:02:17 > 0:02:19Right? Do they look the same in terms of their colour.
0:02:19 > 0:02:22That's what you see, they look different.
0:02:22 > 0:02:26What if I told you that they're actually the same. Will you put money on it?
0:02:26 > 0:02:28Would you bet your life on it?
0:02:28 > 0:02:31You wouldn't be standing here, would you?!
0:02:31 > 0:02:34- Do they look the same now? - That's mad, ain't it?- It looks it.
0:02:34 > 0:02:35Are they the same physically?
0:02:35 > 0:02:39To our amazement and delight, illusions are so powerful
0:02:39 > 0:02:44that even when we know how they work we can still be fooled.
0:02:44 > 0:02:50But for scientists like Dr Beau Lotto, they are far more than fun and games.
0:02:50 > 0:02:57Now, how many people see four blue tiles on the left?
0:02:57 > 0:03:02Yes? I see four blue. How many people see seven yellow tiles on the right?
0:03:02 > 0:03:04I see seven yellow.
0:03:04 > 0:03:07What if I told you they're all grey?
0:03:07 > 0:03:12So if I take, for instance, this tile, what colour is it now?
0:03:12 > 0:03:14Grey.
0:03:14 > 0:03:17If I move it over here,
0:03:17 > 0:03:19what colour is it now?
0:03:19 > 0:03:21Yellowish grey.
0:03:21 > 0:03:24So those tiles are all physically the same.
0:03:24 > 0:03:30Illusions are crucial tools that reveal how the world out there
0:03:30 > 0:03:33can be very different to the one in our heads.
0:03:33 > 0:03:42And it's this gap between reality and what we perceive that holds the key to how our senses work.
0:03:45 > 0:03:52So if you're unsure if seeing is really believing, you're not the only one.
0:03:52 > 0:03:54Is seeing believing?
0:03:54 > 0:03:56What do you mean by that?
0:03:56 > 0:03:57Is seeing believing?
0:03:59 > 0:04:01Is seeing believing?
0:04:03 > 0:04:04No.
0:04:04 > 0:04:06Yes.
0:04:06 > 0:04:08I think it depends who you ask.
0:04:08 > 0:04:10Seeing is literally believing.
0:04:10 > 0:04:12We see what we believe.
0:04:14 > 0:04:15So, yes.
0:04:19 > 0:04:22So it's this question of whether seeing really is believing that's
0:04:22 > 0:04:28helping scientists to open up the fascinating world inside our heads.
0:04:34 > 0:04:41And one of the places they are turning to for inspiration is an ancient and untapped source.
0:04:51 > 0:04:55Magic Singh is a master of illusion.
0:04:55 > 0:05:00His livelihood depends on his ability to confuse, trick and deceive.
0:05:03 > 0:05:07It's something magicians like him have been doing for millennia.
0:05:09 > 0:05:13But now scientists want in on the act.
0:05:13 > 0:05:14Magicians have developed
0:05:14 > 0:05:19really powerful ways of manipulating what we see.
0:05:19 > 0:05:24And many of these techniques have been tried and tested in front of live audiences.
0:05:24 > 0:05:27So by doing so, magicians have sort of developed
0:05:27 > 0:05:32a very solid understanding of how we see the world.
0:05:32 > 0:05:38Psychologist Gustav Kuhn is well versed in the language of illusion.
0:05:38 > 0:05:41In a former life, he was a professional magician.
0:05:43 > 0:05:46Today he's swapped the magic circuit for the science lab,
0:05:46 > 0:05:49but he's convinced there are some important lessons
0:05:49 > 0:05:53to be learnt from plundering the magician's book of tricks.
0:05:56 > 0:05:58So actually take the card out.
0:05:58 > 0:06:01We're really interested in the magic tricks per se,
0:06:01 > 0:06:06but what we focus on is the techniques that magicians use to manipulate your perception.
0:06:06 > 0:06:10OK, I'm not going to put the eye-tracker on you, so if you could just wear these glasses.
0:06:10 > 0:06:15In order to find out how these illusions work, Gustav Kuhn has developed
0:06:15 > 0:06:16an eye-tracking experiment
0:06:16 > 0:06:21to enable him to find out what's happening when we watch certain tricks.
0:06:29 > 0:06:35Now in the vanishing ball illusion, the magician tosses the ball up a couple of times and then on the
0:06:35 > 0:06:39final throw, he just pretends to toss the ball up in the air.
0:06:39 > 0:06:42Yet most people actually experience an imaginary ball
0:06:42 > 0:06:46leave the hand and then sort of disappear somewhere up there.
0:06:46 > 0:06:49But when Gustav analysed his data,
0:06:49 > 0:06:54he discovered the eyes and the brain told a very different story.
0:06:56 > 0:07:00Now, the eye-tracking data showed us that whilst most people were fooled by the illusion,
0:07:00 > 0:07:02the eyes weren't tricked.
0:07:02 > 0:07:07So the eyes, rather than actually looking at the imaginary ball, just stayed on the face.
0:07:07 > 0:07:12And what this showed us is that the illusion really happened in people's minds.
0:07:18 > 0:07:24What this trick really demonstrates is that, rather than seeing what's physically present,
0:07:24 > 0:07:28the way we see the world is based on our prediction of the world.
0:07:28 > 0:07:31So we see things that we expect to see, so in this case,
0:07:31 > 0:07:34we expect the ball to leave the hand, and that's why
0:07:34 > 0:07:39we actually see the ball, even though physically it's not actually present.
0:07:43 > 0:07:48When it comes to what we see, the brain often overrules the eyes,
0:07:48 > 0:07:52even constructing events that may not have actually happened.
0:07:52 > 0:07:58It's an important insight into how our visual system operates in the real world.
0:07:58 > 0:08:02In the real world things happen incredibly quickly and we have to
0:08:02 > 0:08:06respond at great speed and accuracy to visual information.
0:08:06 > 0:08:10This information processing may take up to 150 milliseconds,
0:08:10 > 0:08:14and that kind of delay would just be far too great for us to miss,
0:08:14 > 0:08:17for example, catching a ball or so.
0:08:17 > 0:08:22So rather than just relying on this information, what the visual system does,
0:08:22 > 0:08:25is it predicts what's going to be happening in the future.
0:08:25 > 0:08:30So in many ways, what we see is what's going to happen in the future rather than in the present.
0:08:34 > 0:08:38So seeing may not always be believing.
0:08:38 > 0:08:42But is our sense of hearing any more reliable?
0:08:58 > 0:09:03At any one moment, we are being bombarded by sensory information.
0:09:04 > 0:09:08Our brains do a remarkable job of making sense of it all.
0:09:11 > 0:09:17It seems easy enough to separate the sounds we hear
0:09:17 > 0:09:18from the sights we see.
0:09:22 > 0:09:27But there is one illusion that reveals this isn't always the case.
0:09:28 > 0:09:33Baa, baa, baa.
0:09:33 > 0:09:36Have a look at this. What do you hear?
0:09:36 > 0:09:39Baa, baa, baa.
0:09:41 > 0:09:43Baa, baa, baa.
0:09:43 > 0:09:47But look what happens when we change the picture.
0:09:47 > 0:09:51Faa, faa, faa.
0:09:51 > 0:09:55Faa, faa, faa.
0:09:55 > 0:09:59- Faa, faa... - And yet the sound hasn't changed.
0:09:59 > 0:10:04In every clip, you are only ever hearing "Baa", with a B.
0:10:04 > 0:10:06Baa, baa, baa.
0:10:06 > 0:10:08Baa...
0:10:08 > 0:10:11It's an illusion known as the McGurk effect.
0:10:11 > 0:10:13Take another look.
0:10:13 > 0:10:18- Baa, baa...- Concentrate first on the right of the screen.
0:10:18 > 0:10:22Now to the left of the screen.
0:10:22 > 0:10:28- Baa, baa...- The illusions occurs because what you are seeing clashes with what you are hearing.
0:10:28 > 0:10:34In the illusion, what we see overrides what we hear,
0:10:34 > 0:10:37so the mouth movements we see as we look at a face
0:10:37 > 0:10:39can actually influence what we believe we're hearing.
0:10:39 > 0:10:42If we close our eyes, we actually hear the sound as it is.
0:10:42 > 0:10:47If we open our eyes, we actually see how the mouth movements can influence what we're hearing.
0:10:47 > 0:10:51Baa, baa, baa.
0:10:51 > 0:10:53It's a bizarre effect.
0:10:53 > 0:10:57Remember, the only sound you're hearing is "Baa", with a B.
0:10:57 > 0:10:59Faa, faa, faa.
0:10:59 > 0:11:02Baa, baa, baa.
0:11:02 > 0:11:05What's remarkable about this illusions is
0:11:05 > 0:11:09even knowing how it's done doesn't seem to make a difference.
0:11:09 > 0:11:13The effect works no matter how much you know about the effect.
0:11:13 > 0:11:16I've been studying the McGurk effect for 25 years,
0:11:16 > 0:11:18and I've been the face in the stimuli,
0:11:18 > 0:11:22I've seen stimuli thousands and thousands of times, but the effect still works on me.
0:11:22 > 0:11:25I can't help it, the speech brain takes in that information
0:11:25 > 0:11:29and doesn't care about what outside knowledge you bring to bear.
0:11:29 > 0:11:33Baa, baa, baa.
0:11:33 > 0:11:39The McGurk effect shows us that what we hear may not always be the truth.
0:11:39 > 0:11:45It also helps us to understand what happens when our senses conflict.
0:11:45 > 0:11:48Baa, baa, baa.
0:11:48 > 0:11:50When the brain has the conflicting information,
0:11:50 > 0:11:52it tries to make sense of that conflict,
0:11:52 > 0:11:58and depending on what type of modality is providing more, I guess, salient information,
0:11:58 > 0:12:02that information might override or at least combine with the other information.
0:12:05 > 0:12:12So we can't always trust what we hear because sometimes our sense of vision takes over,
0:12:12 > 0:12:17enabling us to maintain a coherent view of the world.
0:12:22 > 0:12:25But why do illusions have such power?
0:12:25 > 0:12:31Scientist are finding answers in the most surprising of places.
0:12:37 > 0:12:41For bees, colour is a matter of life and death.
0:12:41 > 0:12:45They need to distinguish between colours to find the source of their food.
0:12:45 > 0:12:53And the way bees learn this important lesson can offer us insights into how we perceive.
0:12:54 > 0:13:00One of the great things about studying bees is that bees see colour much the way that we see it.
0:13:00 > 0:13:07They see the same illusions that we see, yet they do it with only a million brain cells.
0:13:07 > 0:13:10Which means that we can actually study how bumble bees see
0:13:10 > 0:13:12and in doing so we can understand how we see.
0:13:15 > 0:13:20Dr Beau Lotto has devised a unique experiment known as the bee matrix,
0:13:20 > 0:13:25where he uses 64 coloured lights to represent flowers.
0:13:26 > 0:13:30The aim of the game is to find the sugar reward.
0:13:31 > 0:13:35We are training the bees to go to blue flowers, as opposed to purple flowers,
0:13:35 > 0:13:38and the way we do that is we reward only the blue flowers,
0:13:38 > 0:13:42reward being sugar water, and we don't put any reward into the purple flowers.
0:13:42 > 0:13:45So if they land on a blue flower, they get a reward.
0:13:45 > 0:13:48And then they associate that with the colour.
0:13:48 > 0:13:54In the top part of the array we have blue flowers surrounded by white flowers, in the bottom part of
0:13:54 > 0:13:57the array we have purple flowers also surrounded by white flowers.
0:13:57 > 0:14:00Only the blue flowers have a sugar reward.
0:14:00 > 0:14:07At first, the bees quickly find their reward by learning the difference between the colours.
0:14:09 > 0:14:11But then things are made more difficult.
0:14:11 > 0:14:20Using filters, Beau changes the colours, so now the blue and purple flowers look exactly the same.
0:14:20 > 0:14:26But remarkably, the bees still fly straight to to the reward.
0:14:29 > 0:14:34So as far as the bee's eye is concerned, those are exactly the same.
0:14:34 > 0:14:38If the bees only remembered the colour of the stimulus,
0:14:38 > 0:14:41they should go to both, because they're physically the same.
0:14:41 > 0:14:45If, however, they've remembered the blue flowers in a context
0:14:45 > 0:14:48and used that context, they should now go only go to the top.
0:14:48 > 0:14:53What we've shown is that that's exactly what happens, which means they are using the context.
0:14:53 > 0:14:58They have remembered and learned the relationships between the colours to solve the puzzle.
0:15:00 > 0:15:04So, to solve the puzzle, the bees don't just look at the colours in the middle
0:15:04 > 0:15:09they also look at the colours that surround them.
0:15:09 > 0:15:13And it's by comparing the central colours to those on the outside
0:15:13 > 0:15:16that they are able to detect the true colour.
0:15:16 > 0:15:21It shows that, for bees, colour isn't just seen in isolation,
0:15:21 > 0:15:26it's entirely dependent on the environment in which it's perceived.
0:15:26 > 0:15:33And what applies to bees also applies to us, every day of our lives.
0:15:38 > 0:15:41Here we have two cubes, except in this case
0:15:41 > 0:15:45it looks as if the cube on the left is under yellow light,
0:15:45 > 0:15:48and the cube on the right is under blue light.
0:15:48 > 0:15:55On the left we have four blue tiles, and on the right we have seven yellow tiles.
0:15:57 > 0:15:59What's amazing about this illusion
0:15:59 > 0:16:04is that the blue tiles on the left are exactly the same, physically,
0:16:04 > 0:16:07as the yellow tiles on the right.
0:16:07 > 0:16:09They're all in fact grey.
0:16:09 > 0:16:14So in this instance the brain has created colours that simply aren't there.
0:16:15 > 0:16:22When the other colours are stripped away, we can see the blue and yellow tiles are just grey.
0:16:22 > 0:16:28Put the scene back, and the colours change back to yellow and blue.
0:16:37 > 0:16:45It shows that, in spite of our strongest instincts, colour is a purely subjective experience,
0:16:45 > 0:16:48governed by the context in which we see it.
0:16:50 > 0:16:53Redness is not a product of the world.
0:16:54 > 0:16:57It doesn't exist unless we're there to make it.
0:16:57 > 0:17:01Blueness is not a part of the world, wavelengths are not colour.
0:17:01 > 0:17:05All they are is little packets of energy called photons, they are not colour.
0:17:07 > 0:17:13We take that and we make perceptions of them, and those perceptions guide our behaviour.
0:17:13 > 0:17:16Illusions fool us because, try as we might,
0:17:16 > 0:17:23we cannot overcome our experience of how we think the world works.
0:17:23 > 0:17:30It's these experiences we store in our heads that really determines what we see.
0:17:30 > 0:17:35What's amazing is that that information, coming from the eyes
0:17:35 > 0:17:38through the thalamus to the back part of the brain,
0:17:38 > 0:17:44actually only makes up 10% of the overall information we use to see.
0:17:44 > 0:17:49The rest of the information comes from other parts of the brain.
0:17:49 > 0:17:53Only 10% of the information we use to see comes from the eyes.
0:17:53 > 0:18:00But are these experiences only built up in the course of our own lives,
0:18:00 > 0:18:03or are some illusions so powerful
0:18:03 > 0:18:08their roots lie far in our distant past?
0:18:26 > 0:18:31Janine Spencer and husband Justin O'Brien are hoping to find out
0:18:31 > 0:18:35if seeing certain illusions is learnt in the course of our lives
0:18:35 > 0:18:37or hard-wired from birth.
0:18:37 > 0:18:43It requires several babies, and a great deal of patience.
0:18:43 > 0:18:47Anybody who studies with babies will know they're notoriously difficult,
0:18:47 > 0:18:50not because they're hard in themselves, they're lovely,
0:18:50 > 0:18:53I love having babies in the lab, but we can't ask them anything.
0:18:56 > 0:19:01There is a number of reasons why it takes such a long time to get baby data,
0:19:01 > 0:19:03pretty normal reasons.
0:19:03 > 0:19:06They cry, they get hungry, they don't like what they're looking at,
0:19:06 > 0:19:09they want to move, they don't want to sit in their car seat,
0:19:09 > 0:19:12so there are a number of reasons and because of that,
0:19:12 > 0:19:15we have to test lots of babies to get enough data.
0:19:15 > 0:19:17BABIES CRY
0:19:19 > 0:19:25In order to find out they are using a famous piece of visual trickery
0:19:25 > 0:19:28called the hollow mask illusion.
0:19:28 > 0:19:33One side of the mask is hollow, but it doesn't necessarily look that way.
0:19:35 > 0:19:40Even when we know it's an illusion, we see it as the convex face.
0:19:40 > 0:19:47Even when we know it's hollow our visual system sees it, we interpret it, as being convex.
0:19:47 > 0:19:54Essentially, our knowledge of faces is overriding what our visual system can see,
0:19:54 > 0:19:56so our depth perception can see that it's hollow,
0:19:56 > 0:19:59but our visual system is overriding that and saying, "no".
0:19:59 > 0:20:01Not in those words,
0:20:01 > 0:20:06it's unconscious of course, but that's a face, so it must be sticking out.
0:20:06 > 0:20:13They've been testing the hollow mask illusion on babies at just four and a half months of age.
0:20:13 > 0:20:17I think it's important to study babies to look at visual illusions
0:20:17 > 0:20:21and any phenomenon where you want to find out if it's innate or not,
0:20:21 > 0:20:25because they don't have that kind of experience we would get as adults.
0:20:25 > 0:20:28The younger you can test them, the better it is.
0:20:31 > 0:20:35It's known babies are good at recognising faces, but the question is,
0:20:35 > 0:20:41do they still see a face when they look at the hollow side of the mask?
0:20:41 > 0:20:47By carefully monitoring their eye movements, it's possible to detect if the babies see the illusion
0:20:47 > 0:20:50by the way the mask captures their attention.
0:20:52 > 0:20:57We measure the amount of interest the baby has in the experiment by looking at their eyes.
0:20:57 > 0:21:01We monitor their eye movements and we time how long they look,
0:21:01 > 0:21:05and when we get to a certain level where they're not looking very much at all,
0:21:05 > 0:21:07we know they're bored of the experiment.
0:21:11 > 0:21:18It's still early days, but 50 babies later a pattern is beginning to emerge.
0:21:19 > 0:21:25From the data we have so far, it would suggest that babies can see the illusion,
0:21:25 > 0:21:30giving an indication that face perception is an innate ability.
0:21:30 > 0:21:36If this pattern continues, it will be the first significant evidence to suggest that seeing
0:21:36 > 0:21:43certain illusions is so powerful it's an ability we've inherited from our parents.
0:21:43 > 0:21:47What's exciting for us about the results we're finding at the moment
0:21:47 > 0:21:53is that it doesn't just tell us about the way babies see, it tells us about our evolutionary past.
0:21:53 > 0:21:59The experience of our ancestors of seeing faces and them being so necessary for survival
0:21:59 > 0:22:02is now written into our DNA, so when a baby's born,
0:22:02 > 0:22:04the first thing they'll look at and show interest in is a face.
0:22:07 > 0:22:13The hollow mask illusion helps explain why seeing illusions may have come about in the first place.
0:22:15 > 0:22:20We've learnt to see what best aids our chances of survival.
0:22:22 > 0:22:25In our evolutionary past, it's important to see faces
0:22:25 > 0:22:27because they could be our enemy.
0:22:27 > 0:22:31It's also not just human faces, it's animal faces as well,
0:22:31 > 0:22:34so we're very good at seeing animal faces.
0:22:34 > 0:22:38So something staring at you through the trees could be a tiger,
0:22:38 > 0:22:41so it's important you interpret something as being a face.
0:22:41 > 0:22:46If it turns out to be a pattern of leaves in the sunlight, you haven't lost anything.
0:22:46 > 0:22:50If you ignore it and it really was a face, then you're in trouble.
0:22:50 > 0:22:52For Janine and Justin,
0:22:52 > 0:22:58over five years of infinite patience is finally paying off.
0:22:58 > 0:23:03Yes, very pleased, we need more babies but we're very pleased with the results we have so far.
0:23:03 > 0:23:07It's only taken five and a half years but we're nearly there.
0:23:12 > 0:23:16Illusions show us that we literally see the world through the lens of the past,
0:23:16 > 0:23:21learning to see in the way that's most useful to us.
0:23:23 > 0:23:25It's an ability that's so important
0:23:25 > 0:23:29it's been handed down through the generations for thousands of years.
0:23:42 > 0:23:48So if you thought being tricked by illusions was a weakness, then think again.
0:23:48 > 0:23:56They may seem to be just a bit of fun, but it turns out they may be the key to our success.
0:23:56 > 0:24:00So what if I told you they're exactly the same?
0:24:00 > 0:24:03- Oh, my God. - So, I do take cheques.
0:24:03 > 0:24:06You just lost so much money!
0:24:06 > 0:24:10Many people think that illusions in fact demonstrate the fragility
0:24:10 > 0:24:13of the human senses, which is in fact completely rubbish.
0:24:13 > 0:24:18Illusions don't tell us that our senses are fragile.
0:24:18 > 0:24:22If they were, we wouldn't be here. Illusions tell us that actually,
0:24:22 > 0:24:27our brains are incredibly capable of constructing meaning
0:24:27 > 0:24:31from the meaningless. We're really good at doing that.
0:24:31 > 0:24:34If we were to process all of the information
0:24:34 > 0:24:36that we feel that we're aware of,
0:24:36 > 0:24:39we would have to grow huge brains
0:24:39 > 0:24:44and have massive heads that our bodies would just fail to support.
0:24:44 > 0:24:49Rather than using this approach, we've evolved to, I think,
0:24:49 > 0:24:55a very clever attentional system that only processes the information that is actually needed.
0:24:58 > 0:25:01So, far from being a disadvantage,
0:25:01 > 0:25:05illusions are a necessary and powerful shortcut
0:25:05 > 0:25:10that lie at the heart of our most sophisticated human abilities.
0:25:12 > 0:25:18And yet the insights we can get from illusions don't end there.
0:25:18 > 0:25:22Scientists are now realising that illusions get even more fascinating
0:25:22 > 0:25:25when the senses start to work together.
0:25:32 > 0:25:38One of the things most of us can hold on to is that our five senses work separately.
0:25:38 > 0:25:42We see with our eyes, hear with our ears,
0:25:42 > 0:25:46taste with our tongue and touch with our skin.
0:25:46 > 0:25:51But scientists have been studying a group of people
0:25:51 > 0:25:54for whom this just isn't the case.
0:25:54 > 0:25:56So when I hear the sea,
0:25:56 > 0:26:00the big clunkiness, as it were of the wave,
0:26:00 > 0:26:05has a kind of dark, dark blue.
0:26:05 > 0:26:10And the pebbley bit has kind of oranges and yellows
0:26:10 > 0:26:13and little bits of white.
0:26:16 > 0:26:22I heard the wind earlier and it had these kind of long shapes,
0:26:22 > 0:26:25a bit like, you know, mackerel fillets.
0:26:25 > 0:26:29You know those shapes, but a bit... The little thin ones.
0:26:29 > 0:26:35Like that, but blue, and quite a lot of them going across.
0:26:38 > 0:26:40I have synaesthesia,
0:26:40 > 0:26:46which means when I experience taste, smell, sound,
0:26:46 > 0:26:48I get visual images.
0:26:48 > 0:26:52Shape, colour and texture to accompany the sense.
0:26:54 > 0:26:58Synaesthesia is a mixing of the senses.
0:26:58 > 0:27:03A sensory experience in one sense can trigger an entirely different reaction in another.
0:27:05 > 0:27:12Whenever Philippa hears, smells, or tastes something, she also sees colours and shapes.
0:27:12 > 0:27:16If I was to have fish and chips, the fish -
0:27:16 > 0:27:22the crispiness, that's angular and then the actually taste
0:27:22 > 0:27:26of the fish is kind of speckeldy brown.
0:27:26 > 0:27:31Nice brown, but yeah, kind of coffee-coloured brown.
0:27:34 > 0:27:38While this experience isn't always pleasurable,
0:27:38 > 0:27:42it's helped drive Philippa's artistic creativity.
0:27:43 > 0:27:48This is a painting of the taste of English mustard.
0:27:49 > 0:27:54It has such a distinctive colour as it is as a product,
0:27:54 > 0:27:57it's bright yellow, but when you taste it, to me,
0:27:57 > 0:28:06it has this massive red hit, which then just disappears into something else
0:28:06 > 0:28:10that ends up, by the time the kind of fumes of it
0:28:10 > 0:28:15are going up through your nose, it's actually quite...pretty.
0:28:15 > 0:28:22So it starts off as a big, massive red hit of taste, which then disperses into something else.
0:28:26 > 0:28:29For years, synaesthesia wasn't taken seriously...
0:28:32 > 0:28:36but now scientists are realising that people like Philippa
0:28:36 > 0:28:43provide important clues as to the way all our senses work.
0:28:43 > 0:28:46We're going to present you with letters and numbers.
0:28:46 > 0:28:49They're, um, going to be coloured either red or green.
0:28:49 > 0:28:55Dr Noam Sagiv has spent his career studying synaesthetes
0:28:55 > 0:28:59in an attempt to understand how their brains are connected.
0:29:01 > 0:29:02So scientists have suspected
0:29:02 > 0:29:07for a long time that what causes synaesthesia is extra connections
0:29:07 > 0:29:12between different parts of the brain, particularly between the sensory areas that are involved.
0:29:12 > 0:29:16For example, if someone has auditory-visual synaesthesia,
0:29:16 > 0:29:23we expect that the auditory part of the brain and the visual part of the brain would be cross-wired.
0:29:23 > 0:29:26And this understanding of how their brains are wired has led to
0:29:26 > 0:29:32an exciting new idea about the way all our senses develop from birth.
0:29:32 > 0:29:34OK?
0:29:34 > 0:29:36- That's it.- I got one wrong.
0:29:36 > 0:29:46What we do know is that the brains of newborns are actually a lot more connected than the brains of adults.
0:29:46 > 0:29:51We start our lives with a lot of connections in our brains and we lose some of them.
0:29:51 > 0:29:55One of the ideas that is trying explain the difference
0:29:55 > 0:30:00between synaesthetes' and non-synaesthetes' development
0:30:00 > 0:30:04is that essentially, synaesthetes were able to keep
0:30:04 > 0:30:09a little bit more of those many connections that we all started our lives with.
0:30:09 > 0:30:17So this condition might have been something we've all had at one time in our lives, but since lost.
0:30:17 > 0:30:24But the similarities between synaesthetes and the rest of us may not end there.
0:30:24 > 0:30:29Scientists are now beginning to suspect that even as adults,
0:30:29 > 0:30:33we may have far more in common with synaesthetes than we realise.
0:30:33 > 0:30:36I can't imagine what it would be like to be alive
0:30:36 > 0:30:39without it...
0:30:39 > 0:30:43because it doesn't impose itself, it's just part of my being.
0:30:43 > 0:30:43So I...
0:30:43 > 0:30:46kind of don't believe that
0:30:46 > 0:30:48people don't have it.
0:30:48 > 0:30:51I think they're just not looking hard enough.
0:30:53 > 0:30:56And this question of the way our senses are connected
0:30:56 > 0:31:01is being answered with the help of another set of bizarre illusions.
0:31:18 > 0:31:25Neuroscientist Charles Spence has recruited some willing volunteers for an unusual multi-sensory feast.
0:31:25 > 0:31:31He's taken his science out of the lab and is going to attempt to trick
0:31:31 > 0:31:36a group of trainee chefs, who rely on their senses more than most of us.
0:31:36 > 0:31:45OK. You've got four coloured drinks in front of you and what I want you to do is to taste each one
0:31:45 > 0:31:48and try and figure out what the flavour is.
0:31:53 > 0:31:57The colours and flavours of the drinks have been mismatched,
0:31:57 > 0:32:00resulting in a certain degree of confusion.
0:32:03 > 0:32:09Just looking at some of the expressions on their faces, you can see confusion and puzzlement.
0:32:12 > 0:32:16One of the people thinks that the yellow drink is apple.
0:32:16 > 0:32:18It was actually strawberry.
0:32:22 > 0:32:26And the red one, they smell like berries, but in fact was lemon.
0:32:30 > 0:32:34I think the green one tasted more of lime.
0:32:34 > 0:32:37Like lime cordial or something like that, rather than mint.
0:32:37 > 0:32:39OK. Excellent.
0:32:39 > 0:32:43Green lime, so it's completely lost the peppermint flavour
0:32:43 > 0:32:47- and it's being completely driven by the eyes.- The light green actually
0:32:47 > 0:32:51reminded me of green washing-up liquid rather than mint.
0:32:51 > 0:32:53Lady's convinced it's washing-up liquid smell.
0:32:53 > 0:32:55And that expectation and knowledge that comes
0:32:55 > 0:32:58from names, from labels, from colours, from textures,
0:32:58 > 0:33:02from ways of presentation, our brains use that all the time
0:33:02 > 0:33:03to tell us what the flavour is.
0:33:03 > 0:33:09People will talk about you eat with your eyes, which is probably much more true than we realise.
0:33:13 > 0:33:19So it's impossible to separate what we see from what we taste.
0:33:19 > 0:33:23But what may be even more surprising is that when it comes to what you eat,
0:33:23 > 0:33:27your ears may be just as important.
0:33:27 > 0:33:29CRUNCHING
0:33:33 > 0:33:36This time the chefs are eating crisps,
0:33:38 > 0:33:44but they are also hearing the sound of their own crunch via headphones.
0:33:44 > 0:33:49But what they don't realise is the noises they hear have been changed.
0:33:49 > 0:33:54When they hear low frequencies, they are tricked into thinking the crisps
0:33:54 > 0:33:58are significantly less crunchy than when they hear higher frequencies.
0:33:59 > 0:34:03When anyone thinks about flavour, the first sense they think about is taste.
0:34:03 > 0:34:08To think about it a bit more, some people say, "Well I suppose smell's involved, too."
0:34:08 > 0:34:14Then they start, possibly if pushed they'll say, "Well maybe colour's got something to do with it."
0:34:14 > 0:34:15And finally a bit of texture.
0:34:15 > 0:34:18Is it soft and slimy or crispy or crunchy?
0:34:18 > 0:34:20But virtually no-one ever thinks about sound.
0:34:20 > 0:34:26The results show hearing can have a significant effect on taste.
0:34:27 > 0:34:34Just playing higher frequencies makes people believe crisps to be over 15% crispier.
0:34:36 > 0:34:43But all this culinary trickery has even more insights to offer.
0:34:43 > 0:34:49The reason these tricks work is because it's impossible to separate one sense from another.
0:34:50 > 0:34:54It's experiments like these that have enabled scientists
0:34:54 > 0:34:58to piece together a revolutionary new understanding of the brain.
0:34:58 > 0:35:03The traditional view was that you had five senses on the outside,
0:35:03 > 0:35:07and the eyes are connected to one bit of the brain, your ears are connected to a different part,
0:35:07 > 0:35:09your skin to somewhere else.
0:35:09 > 0:35:11Each sense had its own bit of brain.
0:35:11 > 0:35:14What we find now is in fact, the eye is talking to the ear almost as soon
0:35:14 > 0:35:18as those signals get from the eye and the ear into the brain.
0:35:18 > 0:35:20From very early on, there are multisensory interactions at work.
0:35:20 > 0:35:23Scientists are saying there is no such thing as a visual brain,
0:35:23 > 0:35:26no such part of the brain that is just doing hearing.
0:35:26 > 0:35:31All of the brain is multisensory, all of the brain is combining all the different senses, all the time.
0:35:33 > 0:35:38So it turns out we are all far more similar to synaesthetes than we've realised.
0:35:38 > 0:35:42It's clear we should no longer think of our senses
0:35:42 > 0:35:48as working independently but as working together as one.
0:35:48 > 0:35:54It's a discovery that has truly revolutionary possibilities.
0:36:03 > 0:36:04- Hi. I'm Larry.- Hi, Edie.
0:36:04 > 0:36:09Very nice to meet you. We're going to do little demonstration here called the rubber hand illusion.
0:36:09 > 0:36:12This illusion may look like fairground fun, but it reveals
0:36:12 > 0:36:18one of the most important new ideas in brain science.
0:36:18 > 0:36:20Right there.
0:36:20 > 0:36:26Good. Can you put this hand down right over here, and curl it up like the rubber hand is curled up
0:36:26 > 0:36:31a little bit. I'm going to try to position the rubber hand so it looks like it's your own.
0:36:31 > 0:36:34- Could you imagine that being your own hand?- Yeah.
0:36:34 > 0:36:40We're going to stroke your finger simultaneously, the rubber finger and your real finger.
0:36:40 > 0:36:46Hopefully this will convince you that the rubber hand is your own. Your brain will adopt this hand.
0:36:46 > 0:36:51In the illusion, simply watching the rubber hand being stroked at the
0:36:51 > 0:36:58- same time as the real hand is enough to trick the brain into adopting it as its own.- We like weird!
0:37:02 > 0:37:08And slowly but surely, you should feel that the hand you're looking at is actually part of your body.
0:37:08 > 0:37:10It feels like you're touching my hand with that one.
0:37:10 > 0:37:14Right, so it feels like this is your hand I'm touching, right?
0:37:19 > 0:37:21- Are you OK?- Yeah.- Good.
0:37:21 > 0:37:23Try that at home with your kids!
0:37:23 > 0:37:26The rubber hand illusion is a wonderful example of how
0:37:26 > 0:37:31multisensory perception can influence how we perceive our own body.
0:37:31 > 0:37:34That's how deep multisensory perception runs.
0:37:34 > 0:37:40When you hold your hand out, it's generally thought that you know it's there because of the information
0:37:40 > 0:37:43you're getting from your muscles and tendons and that sort of thing.
0:37:43 > 0:37:49The rubber hand illusion shows how that can be overridden by visual information.
0:37:49 > 0:37:56The rubber hand illusion shows the powerful connection between what we see and what we feel.
0:37:56 > 0:38:00But it reveals even more than simply the way our senses are connected.
0:38:02 > 0:38:07It hints that a fundamental change in the brain is taking place.
0:38:07 > 0:38:10Oh!
0:38:11 > 0:38:14- Isn't that strange?! - Yeah, that's creepy.
0:38:14 > 0:38:16What might be going on in this illusion is that
0:38:16 > 0:38:20the brain is actually changing to accommodate the new rubber hand.
0:38:20 > 0:38:26Going through some sort of structural change that we call neuroplasticity.
0:38:27 > 0:38:37Neuroplasticity is an exciting new idea that suggests the brain can change in response to experience.
0:38:37 > 0:38:41And this is what's taking place in the rubber hand illusion.
0:38:41 > 0:38:48The brain may be temporarily re-wiring itself to adopt the plastic hand as its own.
0:38:48 > 0:38:50- It really feeling like it's your hand now, huh?- Yes.
0:38:50 > 0:38:52Is that a little weird?
0:38:52 > 0:38:55- Yes.- We like weird in perceptual psychology!
0:38:55 > 0:38:57Here we go.
0:38:59 > 0:39:01- Was that scary?- Yes.
0:39:01 > 0:39:02Good, we like that!
0:39:02 > 0:39:04'Brain plasticity is a terrifically exciting'
0:39:04 > 0:39:07sort of phenomenon for perceptual psychology.
0:39:07 > 0:39:10I think the rubber hand illusion shows that.
0:39:10 > 0:39:13That the brain can change, based on a new experience.
0:39:13 > 0:39:19This is important for somebody, say, who doesn't have vision, to know that they can compensate
0:39:19 > 0:39:23through plasticity with another sense and use that to navigate the world.
0:39:27 > 0:39:32This idea of a plastic, flexible brain is so exciting
0:39:32 > 0:39:35because of the phenomenal possibilities it contains.
0:39:35 > 0:39:42Not only do our senses work together, but it suggests one could be used to replace another.
0:39:44 > 0:39:47CLICKING
0:40:00 > 0:40:04I lost my first eye at the age of seven months, and my second
0:40:04 > 0:40:11at the age of 13 months, to retinoblastoma, which is a retinal tumour.
0:40:13 > 0:40:15I have no visual memories at all.
0:40:15 > 0:40:16CLICKING
0:40:16 > 0:40:21Although Daniel is completely blind, he's developed a remarkable ability
0:40:21 > 0:40:25to see, using his sense of hearing alone.
0:40:25 > 0:40:27CLICKS HIS TONGUE
0:40:30 > 0:40:33People do express surprise
0:40:33 > 0:40:37at a blind person cycling.
0:40:37 > 0:40:40I think different people are good at different things.
0:40:42 > 0:40:45I was good at cycling but I wasn't much for ball sports.
0:40:47 > 0:40:54Using the sound of his tongue clicks, Daniel has learned to echolocate, just like a bat.
0:40:57 > 0:41:00Echolocation is just another way of seeing.
0:41:00 > 0:41:03It's a way of seeing with sound instead of light.
0:41:05 > 0:41:13You extract images from the patterns of sound as they reflect off the environment.
0:41:13 > 0:41:19When Daniel clicks, the sound waves he produces bounce off nearby objects.
0:41:19 > 0:41:28From the returning echoes, Daniel creates an image in his mind, which he uses to navigate the world.
0:41:28 > 0:41:32It's an ability that's enabled him to overcome the impossible.
0:41:32 > 0:41:39I could cycle without echolocating for a brief while, and then it would end uncomfortably.
0:41:41 > 0:41:44It's kind of like they say,
0:41:44 > 0:41:51"Falling is really quite a blast, it's the striking the ground that's the real bummer." So, yeah...
0:41:56 > 0:42:02But Daniel can show us far more than what one extraordinary man can achieve.
0:42:05 > 0:42:11His remarkable bat-like abilities are helping scientists reveal the hidden potential of the brain.
0:42:13 > 0:42:19Professor Lutz Wiegrebe is an expert in bat echolocation, but now in Daniel,
0:42:19 > 0:42:23he's been given the unique opportunity to study his first human subject.
0:42:23 > 0:42:27Wow. That is very cool.
0:42:29 > 0:42:31There's another one!
0:42:35 > 0:42:39Today, Lutz is conducting a series of MRI scans,
0:42:39 > 0:42:45to find out what happens inside Daniel's brain when he echolocates.
0:42:45 > 0:42:50For me personally, this has been a really great experience, because I've been working on the
0:42:50 > 0:42:55echolocation of bats and we've only recently started working
0:42:55 > 0:42:57on echolocation with humans.
0:42:57 > 0:43:04Having Daniel around is like almost being able to talk to a bat, and Daniel is not only exceptionally
0:43:04 > 0:43:10good at echolocation, he's also exceptionally good at verbalising how he does it.
0:43:10 > 0:43:14Inside the scanner, Daniel is hearing virtual echoes.
0:43:19 > 0:43:22This should enable the team to see which parts of his brain
0:43:22 > 0:43:27are activated when he echolocates in the real world.
0:43:28 > 0:43:36Lutz suspects that when Daniel clicks, something remarkable may be happening inside his brain.
0:43:36 > 0:43:45Even though he can't see, the sounds he hears may still be activating parts of his visual brain.
0:43:45 > 0:43:51What we are interested in is so-called cross-modal plasticity, which means that these parts
0:43:51 > 0:43:57of the principal visual cortex are taken over by auditory information.
0:43:59 > 0:44:06Lutz is looking for evidence to show just how malleable the human brain really is.
0:44:08 > 0:44:12Not only can experience temporarily change the brain,
0:44:12 > 0:44:19but as Daniel seems to suggest, these changes can also be permanent.
0:44:19 > 0:44:23It means that at the extreme
0:44:23 > 0:44:25extent of...
0:44:27 > 0:44:31the cross-modal plasticity on a perceptual level that Daniel
0:44:31 > 0:44:35has demonstrated, he can really see with his ears.
0:44:35 > 0:44:41That it's not only that he can process spatial information acquired with his auditory system, but that
0:44:41 > 0:44:47he can also recruit parts of his visual cortex to do this task.
0:44:47 > 0:44:50It's just a demonstration how
0:44:50 > 0:44:55plastic the system is, and how intelligently it's designed.
0:44:55 > 0:44:59If one part of the brain has really no input any more because
0:44:59 > 0:45:06of a sensory deprivation, then this part can be taken over by other modalities.
0:45:07 > 0:45:10As unique individuals like Daniel seem to show,
0:45:10 > 0:45:15the human brain can change and adapt in the most phenomenal way.
0:45:17 > 0:45:21This has implications not only for people whose senses are impaired,
0:45:23 > 0:45:26it has the potential to affect us all.
0:45:41 > 0:45:49For Dr Angus Rupert, finding a way of replacing one sense with another has been a lifelong ambition.
0:45:49 > 0:45:54It's something that for his colleagues at Fort Rucker Aviation Centre in Alabama
0:45:54 > 0:45:57could mean the difference between life and death.
0:45:57 > 0:46:03Since 1990 alone, we've lost between ten and 30 pilots and air crew per year,
0:46:03 > 0:46:06just due to spatial disorientation.
0:46:06 > 0:46:10These are the figures across our army, navy and air force.
0:46:10 > 0:46:14We define spatial disorientation as occurs whenever a pilot misperceives
0:46:14 > 0:46:23the position, motion or attitude of his aircraft, relative to the Earth or other significant objects.
0:46:23 > 0:46:25In other words it's, "Which way is up?"
0:46:25 > 0:46:32In normal circumstances, pilots can correct the problem of spatial disorientation by using their eyes.
0:46:32 > 0:46:38But there are instances when they can't always rely on what they see.
0:46:38 > 0:46:43When you are flying, there is no way for you to know where down is
0:46:43 > 0:46:46unless you are actually looking at the horizon
0:46:46 > 0:46:48or looking at an indicator
0:46:48 > 0:46:51to give you the information in the aircraft.
0:46:54 > 0:46:59But Angus Rupert thinks he has found the solution.
0:46:59 > 0:47:04It comes in the form of the Tactile Situation Awareness System, or TSAS,
0:47:04 > 0:47:10which uses touch to support or replace the sense of vision.
0:47:10 > 0:47:13Together with research pilot John Ramiccio,
0:47:13 > 0:47:21they've found a way of giving pilots spatial awareness by using a series of vibrating pads called tactors.
0:47:26 > 0:47:32So, in this situation we have John wearing tactors incorporated into the shoulder harness.
0:47:32 > 0:47:34These are the ones telling him if he is too high.
0:47:34 > 0:47:39In the seat we have tactors letting him know if he's getting too low
0:47:39 > 0:47:42as well as tactors around his waist here.
0:47:42 > 0:47:43And you can see these tactors
0:47:43 > 0:47:48giving information as to which way he is drifting in space.
0:47:48 > 0:47:52So confident are they in how the system works, it's being put to the test
0:47:52 > 0:47:58on a pilot who will attempt to fly with his eyes completely closed.
0:48:00 > 0:48:04So it's at some risk that we are not successful
0:48:04 > 0:48:08but that's the essence of science, is to experiment
0:48:08 > 0:48:10and so this is raw...
0:48:10 > 0:48:13and un-attempted-before footage.
0:48:13 > 0:48:19We will have Captain Wingate close his eyes, and use the tactile cues to land
0:48:19 > 0:48:26the helicopter so he is going to be fully reliant on feel for spatial orientation.
0:48:28 > 0:48:31I would like you to take off down the runway.
0:48:31 > 0:48:33Do you feel the upper tactor fire?
0:48:33 > 0:48:37It's your shoulder harness telling you that you're above 100 feet, which is perfect.
0:48:41 > 0:48:43Eyes closed.
0:48:43 > 0:48:47Zero the tactor out on the belly button so you know you need a little bit of...
0:48:47 > 0:48:49There is your belly button tactor. Keep your eyes closed.
0:48:49 > 0:48:54Feel that increase, it means velocity is getting fast.
0:48:54 > 0:48:57Slow it down a little bit. Very nice.
0:48:57 > 0:49:00Don't dump power. You are on a nice descent right now.
0:49:01 > 0:49:04I am not going to give you any warnings.
0:49:04 > 0:49:06Your seat pad will tell you 10 ft.
0:49:06 > 0:49:10That's not going around. That is me preparing cushion.
0:49:10 > 0:49:14Right? You are on the ground.
0:49:14 > 0:49:16LAUGHTER Nice job! Nice job!
0:49:18 > 0:49:21That was a first for TSAS right there.
0:49:21 > 0:49:25Eyes closed approach from over 100ft.
0:49:25 > 0:49:27Straight to the ground
0:49:27 > 0:49:30like crazy men. OK.
0:49:30 > 0:49:35For pilots on the front lines, this ability to make more of their
0:49:35 > 0:49:38other senses could make all the difference in the world.
0:49:40 > 0:49:43I've done numerous dust landings sat roadsides where you have
0:49:43 > 0:49:48zero reference with the ground because of the dust outside.
0:49:48 > 0:49:51It's talcum powder - very thick and it envelops you.
0:49:51 > 0:49:57So to be able to use your body and adjust appropriately,
0:49:57 > 0:49:59not only are you saving the guy's life on the ground
0:49:59 > 0:50:04but you also have the guys on board you are trying to protect.
0:50:04 > 0:50:07It gives you another ability to...
0:50:07 > 0:50:09adjust appropriately so that's amazing.
0:50:15 > 0:50:19I am very excited and pleased to be able to say it is a wonderful feeling
0:50:19 > 0:50:23in your heart to know you have an answer for a problem that will save
0:50:23 > 0:50:29many lives under many different types of conditions, not just in aviation but in many other situations.
0:50:32 > 0:50:38This new technology has profound implications,
0:50:38 > 0:50:42helping to reveal what our senses are really capable of.
0:50:42 > 0:50:45As we use touch, we will find there are more
0:50:45 > 0:50:52and more applications in the future and they will be almost limitless, only limited by our imagination.
0:50:52 > 0:50:57And it is up to us to come up with new and better ways to use this.
0:50:57 > 0:51:02And I am sure there are people out there that will take this technology and carry it well into the future.
0:51:04 > 0:51:08And that future may be just around the corner.
0:51:22 > 0:51:26In the small German town of Osnabruck, a group of scientists
0:51:26 > 0:51:30have been pioneering a groundbreaking new experiment.
0:51:30 > 0:51:38They've been pushing the boundary of our sensory capability, attempting to give a man an entirely new sense.
0:51:41 > 0:51:48They've been trying to see if humans can make use of the earth's magnetic field, just like birds.
0:51:49 > 0:51:52So in the beginning we came up with the idea you
0:51:52 > 0:51:57could use the magnetic field of the earth to augment the sensory system
0:51:57 > 0:51:59and extend the sensory experience
0:51:59 > 0:52:01you usually have.
0:52:01 > 0:52:06For the past six years, they've been developing the feelSpace belt -
0:52:08 > 0:52:14a vibrating sensory device that enables the wearer to feel the position of magnetic north.
0:52:16 > 0:52:21So actually that's the prototype of the belt, so we did the first...
0:52:21 > 0:52:23exploratory study with that belt
0:52:23 > 0:52:26and it exists, basically
0:52:26 > 0:52:32of a row of vibrators like in cell phones so these green things are vibrating.
0:52:32 > 0:52:35And at the other side is the most important part.
0:52:35 > 0:52:42The compass feeds information to the control box and the control box then controls
0:52:42 > 0:52:44all these vibrators.
0:52:44 > 0:52:52So if you put it around your waist, like this, there is always one of the vibrators vibrating.
0:52:52 > 0:52:56This one is vibrating because there's north and if I turn like this,
0:52:56 > 0:53:01the next one is vibrating and if I turn like this, the next one is vibrating.
0:53:01 > 0:53:04So a signal's going around my waist.
0:53:04 > 0:53:08I think it's not so important how it looks but it really works so...!
0:53:13 > 0:53:18Udo Wachter was one of the volunteers who took part in the study.
0:53:18 > 0:53:24For six weird weeks, he wore the belt every moment of his waking day.
0:53:24 > 0:53:29In the beginning it was a little bit strange because one isn't very
0:53:29 > 0:53:33used to having a constant buzzing on the body,
0:53:33 > 0:53:37and I'm also a little bit ticklish in certain places!
0:53:38 > 0:53:42But it didn't take very long to get used to it,
0:53:42 > 0:53:47after a day or so, I didn't really realise it was there any more.
0:53:50 > 0:53:57The first clue the team were on to something came when they noticed an important and unexpected phenomenon.
0:53:59 > 0:54:04Strangely, wearers found it difficult to articulate what they were experiencing.
0:54:07 > 0:54:11It was a sign something really significant was taking place.
0:54:12 > 0:54:16It's a characteristic of senses that it's so specific and so special
0:54:16 > 0:54:20that it's hard to communicate to someone who does not have it.
0:54:20 > 0:54:24You can't communicate how it is to see red to someone who has never seen red.
0:54:29 > 0:54:34It hints at the possibility that there is really integration of new sensory information going on.
0:54:34 > 0:54:40In the modern world, there's no shortage of technology to find our way around.
0:54:40 > 0:54:44But the feelSpace system was unlike any other kind of device.
0:54:47 > 0:54:49For the first time it suggested new sensory
0:54:49 > 0:54:54information could be absorbed without having to think about it.
0:54:56 > 0:54:59You might say, you can just have a compass, and look at it and then you
0:54:59 > 0:55:05can find your way anyways but this is what we do not want to find.
0:55:05 > 0:55:09We want to help subjects integrate this kind of
0:55:09 > 0:55:13information in a way which makes it available to them just intuitively.
0:55:13 > 0:55:19Usually senses do not work or they do not need attention so you open your eyes and see,
0:55:19 > 0:55:26you take out earplugs and you hear, and you just put your hand down here and you feel that it's sand here.
0:55:31 > 0:55:34After six weeks of intensive training,
0:55:34 > 0:55:38Udo and the other volunteers faced the ultimate challenge.
0:55:40 > 0:55:48Using only his new magnetic sense, Udo had to navigate blindfold around a previously unseen shape.
0:55:58 > 0:56:02And even when deliberately disorientated,
0:56:03 > 0:56:10he still managed to find his way back to his starting position with remarkable accuracy...
0:56:12 > 0:56:15an otherwise impossible task.
0:56:17 > 0:56:27While wearing the belt, it felt like having a new sense and after a very short time it just felt like it
0:56:27 > 0:56:31should always be there, and it felt like it always was there.
0:56:33 > 0:56:38After its initial trial, the feelSpace belt offers us a glimpse of the future,
0:56:38 > 0:56:44suggesting we may not be limited by the senses we are born with.
0:56:44 > 0:56:48The team are already working on a more extensive trial,
0:56:48 > 0:56:54where they will probe the system's impact on the brain in even greater detail
0:56:54 > 0:57:01but it's clear that when it comes to creating new senses, this is just the beginning.
0:57:01 > 0:57:04Just the idea that there are more ways
0:57:04 > 0:57:07to experience the world is just fascinating.
0:57:07 > 0:57:09I wouldn't say it's going beyond...
0:57:09 > 0:57:11er...
0:57:11 > 0:57:14evolution, it's more like...
0:57:14 > 0:57:18I would say it's more like a part of evolution.
0:57:18 > 0:57:23Because I would say evolution is nothing which stopped ten years ago,
0:57:23 > 0:57:25or 100 years ago, or stopped just now,
0:57:25 > 0:57:33but it's going on. And if it's going to work out and if we are successful with this study and we find out it is
0:57:33 > 0:57:41working then it's an important step for science, but also for everyone who is a human being, in a way.
0:57:47 > 0:57:54Over the past ten years, our understanding of the senses has undergone a revolution.
0:57:56 > 0:58:01It's enabling us to finally unlock the extraordinary potential of our minds...
0:58:05 > 0:58:11and promising to transform all our lives in the most weird and wonderful ways.
0:58:16 > 0:58:19So next time you're not sure whether to believe what you see...
0:58:21 > 0:58:29enjoy it, because these tricks of the mind are how you make sense of your world.
0:58:43 > 0:58:46Subtitles by Red Bee Media Ltd
0:58:46 > 0:58:48E-mail subtitling@bbc.co.uk