Golwg Corff Cymru

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-Every single second of every day...

-..our senses gather information

-about our environment.

-The senses connect us

-to our surroundings.

-I'm Dr Anwen Rees,

-a Physiology lecturer...

-..at Cardiff Metropolitan

-University.

-I'm Dr Katie Hemer, a Bioarchaeology

-specialist at Sheffield University.

-We will look at the way the brain

-uses information...

-..to create

-a unique picture of the world.

-We will look at familiar

-and unfamiliar senses...

-..and how they collaborate.

-And how to trick them.

-SIGHT

-More than any other sense,

-we see the world.

-A glance tells us the size, shape,

-colour and proximity of everything.

-It also identifies objects

-and how fast they're moving.

-How does the sight system

-combine all this information...

-..to create a snapshot

-of our surroundings?

-Should we believe everything we see?

-How do we see the world?

-Light bounces off an object

-and enters the eye via the pupil.

-Muscles in the iris,

-the coloured area of the eye...

-..regulates that light.

-Light passes through a clear lens

-whose thickness can adjust...

-..to allow you to focus on distant

-objects and near objects alike.

-The lens focuses light

-onto the retina.

-There are 100 million cells

-called rods on the retina.

-They allow us

-to see black, white and grey.

-There are also 7 million cones

-which allow us to see colour.

-The three types of cones...

-..are sensitive to primary colours -

-red, blue and green.

-They combine to allow us

-to see millions of colours.

-The retina converts light

-into electrical events.

-They travel down the optic nerve

-to the visual cortex, in the brain.

-Pictures reach the brain upside-down

-but the brain flips them around.

-Most of us have had an eye test

-in the past.

-Almost 70% of the UK population

-wears spectacles.

-What happens to the eyes

-to make us have to do this?

-And why is it so important

-to have regular eye tests?

-I met Dr Norma Davies...

-..at the School Of Optometry

-& Vision Sciences, Cardiff.

-I want you to put your eye

-close to that circle.

-Norma will test my eyes

-to see how healthy they are.

-X, O, A, T.

-You ran a lot of tests

-on my eyes today.

-Can we go through them, please?

-First, we used the optomap,

-the retinal imaging device.

-The green and orange background here

-is the retina.

-The yellow area

-is the optic nerve...

-..which carries messages

-to the brain.

-That's the macula.

-Is the macula important?

-Is the macula important?

-

-Yes.

-The macula is the area of the eye...

-..where the resolution of what

-you see is higher than elsewhere.

-If you damage the macula,

-it has a huge impact on your sight.

-Next, the standard eye test

-with those silly spectacles!

-What were you looking for there?

-We put different lenses in them -

-stronger and weaker.

-The aim was to find the best point

-for you to see the bottom line.

-I asked you if you saw better...

-..with the first or second side

-of the lens...

-..to check for astigmatism.

-Katie, I'd like you to read

-the letters, one eye at a time.

-I can see the top letter.

-I think it's a T.

-What is 20/20 vision?

-On the chart we used...

-..the second line from the bottom

-denotes 20/20 vision.

-Americans call it 20/20.

-We call it 6/6 vision in Britain.

-That's what is classed

-as normal vision.

-X, O, A, T, Y.

-You read the bottom line,

-so your sight is better than normal.

-With my glasses!

-With my glasses!

-

-Yes.

-Place your chin here.

-I didn't enjoy the next test,

-which was for glaucoma.

-Yes, the one where we blow

-a puff of air into your eye.

-Well done. You had a shock there!

-Yes. I didn't like it.

-It gives us a reading

-of the pressure in your eye.

-Glaucoma is a disease

-which affects the optic nerve.

-You cannot regain any sight

-lost as a result of glaucoma.

-There's more to an eye test

-than checking sight.

-Yes, most definitely.

-For example, we can detect glaucoma

-at an early stage.

-Diabetes, high blood pressure

-and high cholesterol...

-..can show up in the eyes of people

-who had no idea anything was amiss.

-There's much more to it

-than a new pair of spectacles.

-Do my eyes look healthy?

-Do my eyes look healthy?

-

-Yes. They look great.

-Does our sight

-differ from that of animals?

-Zoologist, Dr Gethin Evans,

-invited me to see for myself.

-WHISTLING

-Gethin, this is a familiar sight

-in Wales.

-What can these animals tell us

-about our sight?

-The first obvious thing with sheep

-is the position of the eyes.

-They're on the side of the head.

-That's because sheep evolved from

-an animal which was hunted...

-..so better peripheral vision

-was advantageous to them.

-Canine and human eyes are at the

-front of the head, facing forward.

-We can see what's in front of us,

-which is ideal for hunting.

-Is it true that dogs only see

-in black and white?

-No. Dogs do have colour vision

-but it's different from ours.

-There are three types of cone

-in human eyes.

-They allow us

-to see red, blue and green.

-There are only two types of cone

-in canine eyes.

-They see colours

-like brown, blue and yellow...

-..but they don't see red

-in the same way as humans.

-What about other animals?

-There's a wide variety of receptors

-in animals' eyes.

-Birds have four different

-colour receptors.

-Ultraviolet light

-is visible to them, unlike us.

-The mantis shrimp views the world

-in 12 primary colours.

-Nine more than humans.

-Why do animals need to see

-different colours from us?

-It allows them

-to see more of their surroundings.

-The bee goes from flower to flower

-collecting pollen.

-Several flowers have ultraviolet

-patterns on leaves and flowers...

-..which act like airport landing

-strips, guiding bees to the pollen.

-Are there any strange eyes

-in nature?

-Yes - our eyes! Mammals' eyes.

-We all have a blind spot.

-Animals such as the octopus

-don't have a blind spot...

-..because their eyes

-evolved in a different way...

-..but the nerves

-are behind the retina.

-An octopus's eyes are better,

-in some respects, than our eyes...

-..because they don't have

-a blind spot.

-We're all used to wearing these

-in cinemas...

-..to allow us to see images

-on a flat screen in 3D.

-How do we see the world around us

-in three dimensions?

-When we look at something,

-our eyes cross.

-Because our eyes

-are two inches apart...

-..the brain receives

-two slightly different pictures.

-One from the left eye

-and one from the right eye.

-The brain combines the two

-into one picture...

-..and through this,

-it measures depth.

-This is called stereoscopic vision.

-Stereoscopic vision...

-..allows us to create a 3D picture

-of our surroundings.

-Here, at Bangor University,

-a team led by Dr Simon Watt...

-..tests this ability,

-which varies from person to person.

-This machine is unique.

-It can push our stereoscopic vision

-to its limit.

-Two screens show a different image

-for each eye.

-Your eyes are separated, so they see

-the world from different positions.

-They get slightly different images.

-There's information in that about

-the depth structure of the world.

-If you can replicate that by

-presenting one image to one eye...

-..and a different image to the other

-you can simulate that situation.

-A series of mirrors allows the team

-to produce an image...

-..which is as near or far

-from the eye as they choose.

-During the test, different images

-reach the left and right eye.

-The brain must combine them

-to create a 3D pattern...

-..just as it does in everyday life.

-As the test continued,

-I found it increasingly difficult...

-..and my eyes were strained.

-3D technology works by forcing us

-to use our stereoscopic vision...

-..to focus on images in front

-of the screen rather than on it.

-Everyone's sight is different, so

-this isn't enjoyable for everyone.

-With a better understanding

-how stereoscopic vision works...

-..the aim is to improve the

-experience of watching a 3D movie.

-A percentage of the population

-is stereoblind...

-..and can't form 3D images

-using stereoscopic vision.

-This doesn't necessarily render them

-incapable of perceiving depth.

-If you don't have stereo vision,

-you're losing one signal of many.

-If you're trying to judge

-how far apart two things are...

-..you'd really struggle.

-And maybe catching a moving ball.

-For everyday perception

-of the world, you're less certain...

-..but not in a way you'd notice.

-The brain uses size

-to perceive depth.

-So it is possible to trick it.

-In this example, it thinks the chair

-and me are the normal sizes.

-I look small in this position.

-And now, I'm the correct size.

-Hello, Katie!

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-We blink around 15 times per minute

-without really noticing.

-Blinking cleans the eye...

-..but it also means we spend

-10% of our waking hours in darkness.

-Blinking helps us concentrate.

-During a conversation, we tend to

-blink the same time as the speaker.

-Around 10% of us

-are likely to sneeze...

-..when we move from darkness

-into a bright light.

-This is known as

-the photic sneeze reflex.

-Around 8% of men are colour-blind...

-..and can't distinguish colours

-containing red or green.

-Women can be colour-blind,

-but it's far more unusual.

-Eating carrots won't improve

-your night vision.

-This was a story invented

-during World War II...

-..to conceal the fact that Britain

-was using a new type of radar.

-But carrots do contain vitamin A,

-which is good for the eyes.

-At the University Of Bath,

-Dr Michael Proulx...

-..is developing a device with which

-you can 'see' with your ears.

-Low notes are down here.

-High notes are things further away.

-I must close my eyes.

-The camera on the glasses turns

-what's in front of me into sound...

-..which travels from my left ear

-to my right ear.

-The further away the object is,

-the higher the pitch of the note is.

-If the pen is lying flat,

-the sound is constant.

-I hear one constant note.

-I'll change the orientation of it.

-The pen is at an angle, with the

-left end closer than the right...

-..so the pitch of the note

-rises from left to right.

-It's possible to use the glasses

-to identify more complex shapes...

-..such as letters...

-That's a letter O.

-..and even words.

-Oh, my gosh!

-It sounds like W O W.

-I hear the same sound in the right

-as the one in the left...

-..with and O in the middle.

-It was difficult.

-I had to concentrate really hard.

-But I did read a word.

-I'm happy with myself.

-The next step

-is to learn to locate objects.

-It's constant,

-so it must be in the middle.

-I'm getting the hang of this device.

-There's slightly more noise

-on the left, so it must be here.

-There it is.

-The glasses can pick up

-other objects on this table...

-..which then adds a different sound.

-I had to try to focus

-on the object in question...

-..and ignore the other objects.

-I'll hear this sound

-in my sleep tonight!

-Next, the biggest challenge yet -

-using the glasses to follow a path.

-Did you notice the sound change?

-Did you notice the sound change?

-

-Yes.

-When I walked down the path, sound

-came in waves, then it was constant.

-When I hit the bricks, the sound

-was different but constant again.

-I went left but I walked into grass

-because I hadn't turned enough.

-Sound came in waves

-but it was constant.

-I turned again and I got a smooth,

-constant sound and then waves.

-That's how I knew I was on the path.

-The initial application is to find

-ways that the visually impaired...

-..can use it to do things

-sighted people take for granted.

-Being able to navigate your way

-through a city.

-Also if you're in

-an unfamiliar location...

-..and you need to find

-something simple, like an exit.

-Michael gives me one more challenge

-- avoiding obstacles.

-The sound was constant and I knew

-how the grass and the path sounded.

-Once the sound changed,

-I knew he was there.

-I just had to work out

-which way I should move...

-..by listening

-on which side the sound was.

-Then I knew which side to choose.

-Oh!

-LAUGHTER

-These spectacles

-turn everything upside-down.

-They turn a simple task

-into a difficult challenge.

-Such as catching a ball!

-Ready? I'll count to three.

-One, two, three!

-One, two, three!

-

-Ooh!

-One, two, three.

-Everything's upside-down,

-so when the ball goes up...

-..the body instinctively bends down

-to catch it.

-Your head tells you to go one way

-but you should go the other way.

-After a while, the brain adjusts

-to the spectacles...

-..and catching becomes easier...

-..for some people!

-Did you throw it?

-What happens

-once the signals reach the brain?

-The brain must process them and

-create a picture of our environment.

-Here at CUBRIC,

-Cardiff University...

-..Dr John Evans shows me

-how the brain does this.

-What part of the brain

-deals with what we see?

-This is a model of the brain.

-This is the front.

-The part of the brain

-which is responsible for sight...

-..is the visual cortex, at the back.

-It deals with any image which

-reaches the brain via the eyes.

-John's series of MRI tests will show

-how my visual cortex works.

-Are you ready for the first task?

-Yes.

-Look at the cross

-in the centre of the screen.

-These tests will show that different

-areas of the visual cortex...

-..perform different tasks

-while the brain processes images.

-The left side of the brain

-processes things on the right.

-The right side of the brain

-processes things on the left.

-The activity is greater in the green

-areas when focusing on the left.

-The activity in the red areas is

-greater when focusing on the right.

-The activity in the visual cortex

-depends on where the activity is.

-Things can become more complicated.

-There's an area called V5

-at the back of the brain...

-..and it's primarily

-associated with motion.

-If we compare the activity

-when you look at a still image...

-..to the activity

-when you watch moving images...

-..we can see an increase

-in these areas.

-It's vital

-for processing moving images.

-How does the brain recognize faces

-and read expressions?

-John puts me back in the MRI scanner

-to undergo another test.

-Anwen, for the next task you'll see

-images of places or faces.

-People are very good

-at remembering faces.

-We pick out faces in great detail.

-One part of the brain is important

-when we process this information.

-It's known as

-the fusiform face area.

-It's at the base of the brain,

-in this area.

-It works harder when you look at

-faces than when you look at places.

-What happens to this information?

-When the brain

-has processed the information...

-..it decides where it should go.

-Should it make a decision

-as a result of what the eyes saw?

-The information is passed

-to upper areas of the brain...

-..but that's another story!

-Different parts of the brain process

-different elements of what we see.

-From shapes and colours

-to movement and faces.

-The brain gives us a complete

-picture of the world around us.

-That's why we rely more heavily

-on vision than our other senses.

-Next week, we'll focus on hearing.

-How important is hearing

-in everyday life?

-S4C subtitles by Eirlys A Jones

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