Sensation and PerceptionSensation and Perception

Directions: Turn to p. 198Directions: Turn to p. 198 SensationSensation – sensory receptors and the – sensory receptors and the

nervous system receive stimuli from our nervous system receive stimuli from our worldworld

Bottom-up processingBottom-up processing – begins with – begins with the senses and goes to the brain (Ex. the senses and goes to the brain (Ex. Seeing light bounce off book into brainSeeing light bounce off book into brain

PerceptionPerception

PerceptionPerception – process of organizing and – process of organizing and interpreting information.interpreting information.

Top-down processingTop-down processing – – information processing guided by higher information processing guided by higher level mental processes Ex. Saying level mental processes Ex. Saying brown, horse, man or hat.brown, horse, man or hat.

ThresholdsThresholds

Absolute ThresholdsAbsolute Thresholds – the minimum – the minimum stimulus necessary to detect a particular stimulus necessary to detect a particular stimulus 50% of time.stimulus 50% of time.

Stimulus (light, odor, sound, pressure, taste)Stimulus (light, odor, sound, pressure, taste) Ex. – standing on a mountain top, on a clear Ex. – standing on a mountain top, on a clear

night, we can night, we can seesee a candle flame 30 miles. a candle flame 30 miles. Ex. We can Ex. We can tastetaste a teaspoon of sugar in a a teaspoon of sugar in a

gallon of water.gallon of water. EX. Sound on the televisionEX. Sound on the television

Signal Detection TheorySignal Detection Theory

absolute thresholds vary depending on absolute thresholds vary depending on experience, expectations, motivation and experience, expectations, motivation and level of fatiguelevel of fatigue This theory assumes there is no absolute This theory assumes there is no absolute

thresholdthreshold Seeks to explain why the same person’s Seeks to explain why the same person’s

reactions vary as circumstances change. reactions vary as circumstances change.

Ex. Mothers, soldiers, athletes.Ex. Mothers, soldiers, athletes.

Difference ThresholdDifference Threshold

Activity Using 2 sheets of paper cover up Activity Using 2 sheets of paper cover up words on p. 202words on p. 202

Difference ThresholdsDifference Thresholds (aka just noticeable (aka just noticeable difference- jnd)– the minimum difference difference- jnd)– the minimum difference between two stimuli required for detection fifty between two stimuli required for detection fifty percent of the time. percent of the time.

Q. Apply Difference Threshold to sugar and Q. Apply Difference Threshold to sugar and water example?water example?

  

Weber’s LawWeber’s Law

Weber’s LawWeber’s Law – to be perceived as different, – to be perceived as different, two stimuli must differ by a constant minimum two stimuli must differ by a constant minimum percentage (rather than a constant amount)percentage (rather than a constant amount) Ex. Q. If you can tell a difference between Ex. Q. If you can tell a difference between

a 1 lb. weight and a 2 lb. weight…. Are you a 1 lb. weight and a 2 lb. weight…. Are you then able to tell the difference between a then able to tell the difference between a 49 lb. weight and a 50 lb. weight?49 lb. weight and a 50 lb. weight?

Q Why or Why not?Q Why or Why not? Re: last para. on p. 201Re: last para. on p. 201

Subliminal ThresholdsSubliminal Thresholds

below ones absolute threshold for below ones absolute threshold for conscious awarenessconscious awareness

  Q. What do you think of when you hear Q. What do you think of when you hear the words subliminal message?the words subliminal message?

Can we be affected by Can we be affected by weak stimuli?weak stimuli?

Ex. Experimenters subliminally flashed a positive Ex. Experimenters subliminally flashed a positive scene (kittens or a romantic couple) or a negative scene (kittens or a romantic couple) or a negative scene (werewolf or dead body) an instant before scene (werewolf or dead body) an instant before showing a picture of a person. Participants showing a picture of a person. Participants perceived the kitten or werewolf as a flash of light. perceived the kitten or werewolf as a flash of light. The participants gave a more positive rating for the The participants gave a more positive rating for the photos associated with the kitten or romantic couple. photos associated with the kitten or romantic couple.

PrimingPriming- the thought that is placed in the brain - the thought that is placed in the brain immediately preceeding an ambiguous stimuli will immediately preceeding an ambiguous stimuli will cause a person to to think one thing over another …cause a person to to think one thing over another …ape and pea…also yolk, toastape and pea…also yolk, toast

How do subliminal messages How do subliminal messages

workwork??

A word is flashed and immediately followed by A word is flashed and immediately followed by another stimulus that interrupts the brains another stimulus that interrupts the brains processing before conscious perception. processing before conscious perception.

We CAN process information/ sense information We CAN process information/ sense information without being aware of it. without being aware of it.

Q. Can subliminal messagesQ. Can subliminal messages influence buying habits or influence buying habits or ourour behaviors behaviors

Theatres- bottom of 195Theatres- bottom of 195 Ads- crystals of ice, Coors BrewingAds- crystals of ice, Coors Brewing Blue on 200Blue on 200 22ndnd para. 197 para. 197 Complete Critical Thinking Exercise ThresholdsComplete Critical Thinking Exercise Thresholds Subliminal Messages in Disney Movies – YouTubeSubliminal Messages in Disney Movies – YouTube Issues - Knowmore.org (Disney’s image vs. reality)Issues - Knowmore.org (Disney’s image vs. reality) Walt Disney Brand (Phillip Morris, Altria), Haliburton Walt Disney Brand (Phillip Morris, Altria), Haliburton

KBR), Harris Teeter and Kroger???KBR), Harris Teeter and Kroger???

  critical thinking exercisecritical thinking exercise

Sensory AdaptationSensory Adaptation

– – our diminishing sensitivity to an our diminishing sensitivity to an unchanging stimulus. unchanging stimulus. 

Q. Give examples?Q. Give examples? Moving your watch up your arm, ring on Moving your watch up your arm, ring on

finger, a terrible smell in the house, Matthews finger, a terrible smell in the house, Matthews train, swimming in cold water, dark room – train, swimming in cold water, dark room – with time we become less sensitive to these with time we become less sensitive to these stimuli stimuli

  

Exploring Our Exploring Our SensesSenses

VISION AND HEARINGVISION AND HEARING

VISION VISION

Step 1 – GATHERING LIGHTStep 1 – GATHERING LIGHT Light is Light is reflected off objects and gathered by reflected off objects and gathered by

the eyethe eye Visible light to humans is only a small part of Visible light to humans is only a small part of

the the electromagnetic spectrumelectromagnetic spectrum

The color we see depends The color we see depends on 2 factors…on 2 factors…

Light Intensity - BRIGHTNESSLight Intensity - BRIGHTNESS Light Wavelength – COLORSLight Wavelength – COLORS

(longest)ROYGBIV(shortest)(longest)ROYGBIV(shortest)

VISION VISION Step 2 – LIGHT THROUGH THE EYEStep 2 – LIGHT THROUGH THE EYE

Light enters the eye through the Light enters the eye through the corneacornea – protective – protective covering of the eye covering of the eye

Light goes through the Light goes through the pupilpupil – adjustable opening in – adjustable opening in the center of the eye the center of the eye

IrisIris is the muscle that controls the opening of the is the muscle that controls the opening of the pupil. pupil.

Light is focused by theLight is focused by the lenslens – transparent structure – transparent structure behind the pupilbehind the pupil Stare at your finger, then change focus to the wall, and Stare at your finger, then change focus to the wall, and

then to your finger… you should feel the muscles changing then to your finger… you should feel the muscles changing the shape of your lens. Accomodation is the processthe shape of your lens. Accomodation is the process

As light passes through the lens, the image is As light passes through the lens, the image is flipped upside down and inverted.flipped upside down and inverted.

PARTS OF THE EYEPARTS OF THE EYE

Images are inverted on Images are inverted on the retinathe retina

The image of the "outside world" is inverted on our The image of the "outside world" is inverted on our retina, even though the world appears right side up. retina, even though the world appears right side up. Interestingly, if one wears prisms to make the retinal Interestingly, if one wears prisms to make the retinal image right side up, the world will appear inverted.image right side up, the world will appear inverted.

THE RETINATHE RETINA RodsRods – detect black, white, and – detect black, white, and

gray; necessary for peripheral gray; necessary for peripheral vision and twilight visionvision and twilight vision Some nocturnal animals have Some nocturnal animals have

retinas made up of nearly all retinas made up of nearly all rods. rods.

ConesCones – concentrated near the – concentrated near the center of the retina (center of the retina (foveafovea), ), function in daylight and well lit function in daylight and well lit conditions, detects detail and conditions, detects detail and color.color. Light strikes the rods and cones, Light strikes the rods and cones,

produces a chemical change to produces a chemical change to neural signals, and activates neural signals, and activates bipolar cellsbipolar cells, which in turn , which in turn activate activate ganglion cellsganglion cells..

VISIONVISION

Step 3 – Transduction Step 3 – Transduction Transduction Transduction – process by which our – process by which our

sensory systems convert energy into sensory systems convert energy into neural impulses. (prevalent with vision neural impulses. (prevalent with vision and hearing)and hearing)

WITHIN THE EYEWITHIN THE EYE

Blind spotBlind spot – where the optic nerve leaves the – where the optic nerve leaves the eyeeye

FoveaFovea – center of the retina with only cones – center of the retina with only cones (no rods). Helps see details. (acuity)(no rods). Helps see details. (acuity)

Focus on one word in the text, what happens to the other Focus on one word in the text, what happens to the other words around that word?words around that word?

BLIND SPOTBLIND SPOT

Blind Spot – where the optic nerve leaves Blind Spot – where the optic nerve leaves the eye.the eye.

Look on pages 203 in the text for a Look on pages 203 in the text for a demonstration of your blind spot.demonstration of your blind spot.

Seeing in the DarkSeeing in the Dark

In dim lightIn dim light Cones become inadequate, rods remain Cones become inadequate, rods remain

sensitivesensitive Pupils dilate in darkness to let more light to Pupils dilate in darkness to let more light to

reach the retina’s peripheryreach the retina’s periphery

Nearsighted vs. FarsightedNearsighted vs. Farsighted

NearsightedNearsighted – light – light rays from distant rays from distant objects focus in front objects focus in front of the retinaof the retina Seeing distant objects Seeing distant objects

is difficultis difficult FarsightedFarsighted – light – light

rays from nearby rays from nearby objects focus behind objects focus behind the retinathe retina Seeing close objects is Seeing close objects is

difficultdifficult

Feature Detectors Feature Detectors

Feature detectorsFeature detectors – nerve cells in the brain – nerve cells in the brain (in the visual cortex) that respond to specific (in the visual cortex) that respond to specific features of the stimulus, such as shape, features of the stimulus, such as shape, angle, movement. Hubel and Weisel. Colin angle, movement. Hubel and Weisel. Colin Blakemore does terrible things to kittens. For Blakemore does terrible things to kittens. For science!science!

Recall the concept of brain specialization and Recall the concept of brain specialization and association areas from Ch. 2.association areas from Ch. 2.

Recall Fmri scanning 60 minutes- toolsRecall Fmri scanning 60 minutes- tools

Face BlindnessFace Blindness

Face Blindness: When everyone is a Face Blindness: When everyone is a stranger - CBS Newsstranger - CBS News

Parallel ProcessingParallel Processing

Parallel processingParallel processing – – The brain processes The brain processes several aspects of a several aspects of a problem simultaneously problem simultaneously (contrasts with the step-(contrasts with the step-by-step processing by-step processing found in a computer)found in a computer)

The brain divides a The brain divides a visual scene into color, visual scene into color, depth, motion and form. depth, motion and form.

Theories of Color Vision Theories of Color Vision

Young – Helmholtz Young – Helmholtz trichromatic theorytrichromatic theory – – We have three types of We have three types of cones in the retina. cones in the retina. (Cones that detect red, (Cones that detect red, blue and green) These blue and green) These cones are activated in cones are activated in different combinations to different combinations to produce all colors. produce all colors.

Theories of Color VisionTheories of Color Vision

Opponent-process Opponent-process theory – theory – Sensory Sensory receptors in the receptors in the retina come in pairs. retina come in pairs. If one sensor is If one sensor is stimulated, then the stimulated, then the other is inhibited other is inhibited from firing.from firing. Red/ greenRed/ green, , Yellow/ Yellow/

blueblue, , Black/ whiteBlack/ white

Opponent Processing Opponent Processing Theory Theory

The opponent processing theory explains The opponent processing theory explains afterimages p. 213afterimages p. 213

Opponent Processing Opponent Processing TheoryTheory

The opponent process The opponent process theory explains theory explains colorblindnesscolorblindness Colorblindness – if Colorblindness – if

dichromaticdichromatic one cannot one cannot see either red/green see either red/green shades or blue/yellow shades or blue/yellow shades, if shades, if monochromaticmonochromatic one can one can only see shades of gray.only see shades of gray.

P.213P.213

HEARINGHEARING

AuditionAudition – sense of hearing – sense of hearing Sound waves are vibrations in the air (not Sound waves are vibrations in the air (not

electromagnetic waves) and are collected electromagnetic waves) and are collected by our ears.by our ears.

Vibrations go through the process of Vibrations go through the process of transductiontransduction. – Vibrations are changed . – Vibrations are changed to neural impulses. to neural impulses.

2 important characteristics 2 important characteristics of sound wavesof sound waves

AmplitudeAmplitude – height of the wave / determines loudness – height of the wave / determines loudness Loud sounds – tall wavesLoud sounds – tall waves Soft sounds – short wavesSoft sounds – short waves

FrequencyFrequency – length of the wave / determines pitch – length of the wave / determines pitch High pitch – faster frequency High pitch – faster frequency

Low pitch – slower frequencyLow pitch – slower frequency

Sound Travels Through Sound Travels Through the Earthe Ear Sound enters the outer earSound enters the outer ear

Waves travel down the Waves travel down the ear canalear canal (aka auditory canal) (aka auditory canal) until they reach the eardrumuntil they reach the eardrum

EardrumEardrum – thin membrane that vibrates as the sound – thin membrane that vibrates as the sound waves hit itwaves hit it

Eardrum connects to the middle earEardrum connects to the middle ear Three bones in the middle ear – Three bones in the middle ear – hammerhammer, , anvilanvil, and , and

stirrupstirrup Passes vibrations of to the inner earPasses vibrations of to the inner ear

Inner earInner ear Waves reach the Waves reach the cochleacochlea – a snail shaped fluid filled – a snail shaped fluid filled

tube through which sound waves trigger neural impulses tube through which sound waves trigger neural impulses (this is where (this is where transductiontransduction occurs) which travel to the occurs) which travel to the brain.brain.

PARTS OF THE EARPARTS OF THE EAR

SOUND LOCALIZATIONSOUND LOCALIZATION

Sound LocalizationSound Localization Sound coming from the right, enters your Sound coming from the right, enters your

right ear sooner that your left right ear sooner that your left The right ear also receives a more intense The right ear also receives a more intense

sound than the left ear.sound than the left ear.

HEARING LOSSHEARING LOSS

Hearing Loss Hearing Loss Conduction hearing lossConduction hearing loss – due to damage – due to damage

of the mechanical system that conducts of the mechanical system that conducts sound waves to the cochleasound waves to the cochlea Ex. eardrum is puncturedEx. eardrum is punctured

Sensorineural hearing loss (aka nerve Sensorineural hearing loss (aka nerve deafness)deafness) – due to damage to the cochlea’s – due to damage to the cochlea’s receptor cells or the auditory nerves.receptor cells or the auditory nerves. Ex. Loud noises, aging, heredity Ex. Loud noises, aging, heredity

Noise levels higher than Noise levels higher than 85 decibels are harmful…85 decibels are harmful…

Gate Control TheoryGate Control Theory

The spinal cord contains a neurological The spinal cord contains a neurological “gate.” Some pain messages have higher “gate.” Some pain messages have higher priority than others. The high priority priority than others. The high priority message is sent and the “gate” swings open message is sent and the “gate” swings open and allows it to pass to the brain. The “gate” and allows it to pass to the brain. The “gate” closes for low priority messages – thus we closes for low priority messages – thus we do not feel them. Endorphins can help the do not feel them. Endorphins can help the gate to swing shut. gate to swing shut. Placing ice on the injured toe stimulates gate Placing ice on the injured toe stimulates gate

closingclosing