PerceptionPerceptionProfessor CarneyProfessor Carney

Totally Ripped off From Several Totally Ripped off From Several Internet SitesInternet Sites

PerceptionPerception

• To survive, must be able to perform 3 interrelated activities: To survive, must be able to perform 3 interrelated activities: – 1. Sensing stimuli1. Sensing stimuli

– 2. Processing stimuli (interpreting)2. Processing stimuli (interpreting)

– 3. Responding to stimuli (brain sends message to muscles)3. Responding to stimuli (brain sends message to muscles)

• Ex: Traffic lightEx: Traffic light– 1. Sensing stimuli1. Sensing stimuli

• See red lightSee red light

– 2. Professing stimuli2. Professing stimuli

• Red means stopRed means stop

– 3. Responding to stimuli3. Responding to stimuli

• Putting foot on brakePutting foot on brake

Copyright © Prentice Hall 2007 2-2

PerceptionPerception

• The process of organizing and The process of organizing and making sense of sensory making sense of sensory information.information.

PerceptionPerception

• Vision our most important sensory Vision our most important sensory process?process?

• About 80% of the information we About 80% of the information we receive about the world reaches us receive about the world reaches us through vision.through vision.

• We don’t have the top of the line eye We don’t have the top of the line eye evolutionary speaking.evolutionary speaking.– Antelope has 8 x’s magnification in it’s Antelope has 8 x’s magnification in it’s

lens.lens.

PerceptionPerception

• Visual perception is extremely Visual perception is extremely complicated.complicated.

• Either pick a partner and look at their Either pick a partner and look at their eye as we continue or look into a mirror.eye as we continue or look into a mirror.

• This simple clip made for children This simple clip made for children simplifies and clarifies the workings of simplifies and clarifies the workings of the eyes. the eyes. http://www.brainpop.com/health/bodysyhttp://www.brainpop.com/health/bodysystems/eyes/stems/eyes/

Anatomy of the EyeAnatomy of the Eye

ProcessProcess

• CorneaCornea

• IrisIris

• PupilPupil

• LensLens

• RetinaRetina

Sclera or the White PartSclera or the White Part

• White part of the White part of the eyeball is the eyeball is the sclera (sklair-uh). sclera (sklair-uh).

• Made of a tough Made of a tough material.material.

• Covers most of the Covers most of the eyeball.eyeball.

Sclera or the White PartSclera or the White Part

• Think of the Think of the sclera as your sclera as your eyeball's outer eyeball's outer coat. coat.

CorneaCornea• Transparent dome.Transparent dome.

• In front of the In front of the colored part of the colored part of the eye. eye.

• Helps the eye focus Helps the eye focus as light makes its as light makes its way through.way through.

CorneaCornea• Made of clear tissue. Made of clear tissue. • Like a windshield the it Like a windshield the it

gives your eye a clear gives your eye a clear window to view the window to view the world. world.

• No blood supply & No blood supply & easily transplanted. easily transplanted.

• Shown is an artificial Shown is an artificial cornea but can come cornea but can come from a cadaver.from a cadaver.

IrisIris

• Behind the cornea:Behind the cornea:– IrisIris– PupilPupil– Anterior chamberAnterior chamber

• Iris the colorful Iris the colorful part of the eyepart of the eye

Iris Cont.Iris Cont.

• Muscles attached Muscles attached to it change its to it change its shape.shape.

• Controls how Controls how much light goes much light goes through the pupil through the pupil – Shutter on a Shutter on a

cameracamera

PupilPupil

• Black circle in Black circle in the center of the the center of the IrisIris

• It is an opening It is an opening in the Iris.in the Iris.

• Lets light enter Lets light enter the eye. the eye.

PupilPupil

• When we say, “Your Pupil is dilated”, what When we say, “Your Pupil is dilated”, what are we really saying?are we really saying?– Your Iris is expanding or contracting to let in Your Iris is expanding or contracting to let in

more or less light.more or less light.

Drug Overdose of Unconscious Drug Overdose of Unconscious Person Person

• Doctors can tell before Doctors can tell before a toxicology report that a toxicology report that someone has had a drug someone has had a drug overdose. overdose.

• Narrow pinpoint pupilNarrow pinpoint pupil

Anterior ChamberAnterior Chamber

• Space between the Space between the cornea & Iriscornea & Iris

• Filled with a Filled with a transparent fluidtransparent fluid

– Nourishes the Nourishes the eye eye

– Keeps it healthyKeeps it healthy

LensLens

• After light enters After light enters the pupil, it hits the the pupil, it hits the lens. lens.

• Lens is behind the Lens is behind the Iris Iris – Clear and colorlessClear and colorless– Focuses light rays Focuses light rays

on the back of the on the back of the eyeball, the retinaeyeball, the retina

LensLens

• Works like the Works like the lens of a movie lens of a movie projector projector

• You see a stream You see a stream of light coming of light coming from the from the projection boothprojection booth

LensLens

• Light goes through a Light goes through a lens, which is lens, which is focusing the images focusing the images onto the screen, so onto the screen, so you can see the movie you can see the movie clearly. clearly.

• In the eye's case, the In the eye's case, the film screen is your film screen is your retina.retina.

Ciliary MuscleCiliary Muscle• The lens is The lens is

suspended by suspended by fibersfibers

• These fibers are These fibers are attached to the attached to the ciliary muscle. ciliary muscle.

• It changes the It changes the shape of the lensshape of the lens

Ciliary Muscle Cont.Ciliary Muscle Cont.• It changes the It changes the

shape of the lensshape of the lens• Process calledProcess called

• AccommodationAccommodation

Ciliary Muscle Cont.Ciliary Muscle Cont.• When you look at When you look at

things up close, things up close, the lens becomes the lens becomes thicker to focus thicker to focus the correct image the correct image onto the retina.onto the retina.

• When you look at When you look at things far away, things far away, the lens becomes the lens becomes thinner.thinner.

Vitreous Body (vih-tree-us) Vitreous Body (vih-tree-us)

• Biggest part of the eyeBiggest part of the eye• Sits behind the lens Sits behind the lens

Forms 2/3 of the eye's Forms 2/3 of the eye's volumevolume

• Gives the eye its shape, Gives the eye its shape, keeps the retina in keeps the retina in place.place.

• Filled with a clear, Filled with a clear, jelly-like material but is jelly-like material but is 99% water99% water

Vitreous Body Cont.Vitreous Body Cont.

• Toy eyeballs are Toy eyeballs are sometimes squishy sometimes squishy because they're made to because they're made to feel like they're filled feel like they're filled with vitreous humor. with vitreous humor.

• Light passes through Light passes through the lensthe lens

• It shines straight It shines straight through the vitreous through the vitreous humor to the back of humor to the back of the eye.the eye.

RetinaRetina

• Film that light hits. Film that light hits.

• The beginning of our The beginning of our perception of light.perception of light.

• Very back of the eyeVery back of the eye

• It holds all the It holds all the receptors for vision.receptors for vision.

RetinaRetina

• Takes the light the Takes the light the eye receives and eye receives and changes it into changes it into nerve signals so nerve signals so the brain can the brain can understand what understand what the eye is seeing.the eye is seeing.

DeathDeath

• When someone dies they get retinal blood When someone dies they get retinal blood columns called “boxcars”. They look like a columns called “boxcars”. They look like a little train. little train.

• This is why the doctor shines a light into This is why the doctor shines a light into someone's eye to see if they are still alive. someone's eye to see if they are still alive.

• If dead the pupil will not contract and also If dead the pupil will not contract and also he/she will see the boxcars.he/she will see the boxcars.

• Pupil dilates at death, shine light in there is Pupil dilates at death, shine light in there is no reflex.no reflex.

Light Hitting The RetinaLight Hitting The Retina

Sensory CodingSensory Coding

• Activation of retinal Activation of retinal cells by light results in cells by light results in action potentials that action potentials that travel along neurons travel along neurons that project to the that project to the occipital cortexoccipital cortex

Rods and ConesRods and Cones

• Retina uses cells to Retina uses cells to process light. process light.

• In each eye:In each eye:– Rods Rods

• 120 million 120 million • PhotoreceptorsPhotoreceptors

– Cones Cones • 7 million7 million• Color receptors Color receptors

RodsRods

• Name: shaped Name: shaped like a column. like a column.

• See in black, See in black, white, & shades white, & shades of gray of gray

Rods Cont.Rods Cont.

• Notice that we may think we are seeing Notice that we may think we are seeing color because we expect something to be color because we expect something to be a certain color.a certain color.

• Tell us shape & movement of somethingTell us shape & movement of something

• Rods are super-sensitiveRods are super-sensitive

• Allow us to see in the dark for survival.Allow us to see in the dark for survival.

Periferal VisonPeriferal Vison

• Periferal field rods increase. Hunters know Periferal field rods increase. Hunters know in dark settings to not look directly at your in dark settings to not look directly at your prey, better dark vision. I have personally prey, better dark vision. I have personally seen this with deers. They look at your seen this with deers. They look at your sideways. sideways.

ConesCones

• Color receptorsColor receptors• Sense Sense color • Need more light Need more light

than rods to work than rods to work wellwell

• Work best in normal Work best in normal or bright lightor bright light

• Retina has 3 types of Retina has 3 types of cones. cones.

Cones Cont.Cones Cont.

• The retina has 3 The retina has 3 types of cones. types of cones.

• Each cone type is Each cone type is sensitive to one of sensitive to one of three different three different colors — red, green, colors — red, green, or blue — to help or blue — to help you see different you see different ranges of color. ranges of color.

Cones Cont.Cones Cont.

• Together, these Together, these cones can sense cones can sense combinations of light combinations of light waves that enable waves that enable our eyes to see our eyes to see millions of colors. millions of colors.

Feature DetectorsFeature Detectors

• Nerve cells that pick up specific featuresNerve cells that pick up specific features– MovementMovement– ShapeShape– DepthDepth

Optic NerveOptic Nerve

• Messenger in back eye. Messenger in back eye.

• Rods & cones of retinaRods & cones of retina– Change colors & shapes into millions of nerve Change colors & shapes into millions of nerve

messages. messages.

• Optic nerve carries those messages from eye Optic nerve carries those messages from eye > brain> brain

• Optic nerve serves as a high-speed telephone Optic nerve serves as a high-speed telephone line connecting eye > brain. line connecting eye > brain.

Optic NerveOptic Nerve

• When you see an image, When you see an image, your eye "telephones" your eye "telephones" your brain with a your brain with a report on what you are report on what you are seeing so the brain can seeing so the brain can translate that report translate that report into "car," “person," or into "car," “person," or “Big Mac," or whatever “Big Mac," or whatever the case may be.the case may be.

Optic NerveOptic Nerve

• Put an x on the wall and a dot on a card, close Put an x on the wall and a dot on a card, close one eye, and the dot will disappear at your one eye, and the dot will disappear at your blind spot.blind spot.

• Blind spotBlind spot– Where the Optic Nerve pierces the retinaWhere the Optic Nerve pierces the retina

• No receptor cells to pick up imagesNo receptor cells to pick up images

• Brain fills in the blankBrain fills in the blank

Eye TattooingEye Tattooing

• Some people have started getting Some people have started getting tattoos on their eyeballs. And we're tattoos on their eyeballs. And we're not talking about permanent not talking about permanent makeup or anything else on the makeup or anything else on the outsideoutside of the eye -- we're talking of the eye -- we're talking ink injected right into the cornea.ink injected right into the cornea.

Eye Tattooing Cont.Eye Tattooing Cont.

• Corneal tattooing is dangerous for a Corneal tattooing is dangerous for a number of reasons, because in addition number of reasons, because in addition to the usual risks the cornea version can to the usual risks the cornea version can include infection, perforation, include infection, perforation, hemorrhage, scarring, and blindness. It hemorrhage, scarring, and blindness. It started as a means of repairing eye started as a means of repairing eye damage and covering scarring, but it's damage and covering scarring, but it's becoming a more and more popular becoming a more and more popular cosmetic procedure. cosmetic procedure.

Eye Tattooing Cont.Eye Tattooing Cont.

• If If you worry about regretting that yin-you worry about regretting that yin-yang symbol on your ankle, just think yang symbol on your ankle, just think how you'll feel with kaleidoscope eyes. how you'll feel with kaleidoscope eyes.

• So would you let a tattoo artist stick a So would you let a tattoo artist stick a needle in your eye? Talk about regret! needle in your eye? Talk about regret!

Perceptual SetPerceptual Set

Perceptual SetPerceptual Set