Sensation and PerceptionSensation and Perception

Sensation: process by which our senses Sensation: process by which our senses receive energy from the environment.receive energy from the environment.

Perception: making sensory information Perception: making sensory information meaningful to usmeaningful to us

Count the black dotsCount the black dots

Chalk drawings by Julian BeeverChalk drawings by Julian Beever

ThresholdsThresholds Absolute Thresholds- the lowest level of a Absolute Thresholds- the lowest level of a

stimulus a person can detect 50% of the time.stimulus a person can detect 50% of the time. http://www.youtube.com/watch?v=4YWSerwlWjMhttp://www.youtube.com/watch?v=4YWSerwlWjM

Have you ever been home alone and watched a Have you ever been home alone and watched a scary movie?scary movie?

Signal detection theory-absolute threshold can Signal detection theory-absolute threshold can change with psychological factorschange with psychological factors

Subliminal stimulation-falls just below the Subliminal stimulation-falls just below the absolute thresholdabsolute threshold

http://www.youtube.com/watch?v=2NPKxhfFQMs – http://www.youtube.com/watch?v=2NPKxhfFQMs – subliminal advertisementsubliminal advertisement

Difference Threshold (Just noticeable Difference Threshold (Just noticeable difference)- the point at which a person can difference)- the point at which a person can tell a stimulus has changed in intensity 50% of tell a stimulus has changed in intensity 50% of the time.the time.

Weber’s Law- The difference threshold is Weber’s Law- The difference threshold is greater for a strong stimulus than a weak one.greater for a strong stimulus than a weak one.

1.1. Cup of water in oceanCup of water in ocean

2.2. Money in bank Money in bank

3.3. Turning up TVTurning up TV

Sensory Adaptation- neurons stop firing in Sensory Adaptation- neurons stop firing in response to a constant stimulus.response to a constant stimulus.

Ex. Air conditioning/watch/bad smell/first Ex. Air conditioning/watch/bad smell/first bite of dessert bite of dessert

Remember our senses are not always accurate Remember our senses are not always accurate and things are not always what they seem. We and things are not always what they seem. We may perceive things differently than they may perceive things differently than they really are such as in this dragon illusionreally are such as in this dragon illusion

http://www.youtube.com/watch?http://www.youtube.com/watch?v=2K39Q9zvQoEv=2K39Q9zvQoE

What sense do we rely on the What sense do we rely on the most?most?

Vision:Vision:

TransductionTransduction- change one form of energy to - change one form of energy to anotheranother

Our eyes turn energy from light waves into Our eyes turn energy from light waves into nueral impulses (brain waves)nueral impulses (brain waves)

CorneaCornea- protective covering around eye- protective covering around eye

PupilPupil- hole that light passes through- hole that light passes through

IrisIris- muscle controlling pupil size and how - muscle controlling pupil size and how much light gets inmuch light gets in

LensLens- will focus light- will focus light

AccommodationAccommodation- lens changes shape to focus - lens changes shape to focus light properlylight properly

RetinaRetina- light sensitive back of the eye (has - light sensitive back of the eye (has rods and cones)- transduction happens here.rods and cones)- transduction happens here.

Acuity-how well we seeAcuity-how well we see Nearsightedness-can’t see farNearsightedness-can’t see far Farsighted-can’t see nearFarsighted-can’t see near

Photoreceptors in the retinaPhotoreceptors in the retina conescones

1.1. See detailSee detail

2.2. See colorSee color

3.3. Fewer of themFewer of them rodsrods

1.1. See little detailSee little detail

2.2. See in black and whiteSee in black and white

3.3. More of themmMore of themm

Feature Detection-different parts Feature Detection-different parts of our brain detect different of our brain detect different

featuresfeatures Parallel process-the different features are Parallel process-the different features are

detected at the same timedetected at the same time

Color VisionColor Vision

Young-Helmholtz trichromatic theory-every Young-Helmholtz trichromatic theory-every color is a combination of red, green and bluecolor is a combination of red, green and blue

Opponent process theory-opposing switches in Opponent process theory-opposing switches in the retina detect colors in combinations of red the retina detect colors in combinations of red vs. green, blue vs. yellow and black vs. whitevs. green, blue vs. yellow and black vs. white

Afterimages- if we stare at a color for a long Afterimages- if we stare at a color for a long time and look away, we see the opposite colortime and look away, we see the opposite color

Color Constancy-we judge color against its Color Constancy-we judge color against its surroundings so color appears constant despite surroundings so color appears constant despite changing light levelschanging light levels

Color Blindness is best explained by the Color Blindness is best explained by the opponent process theoryopponent process theory

The most common type is red/greenThe most common type is red/green The second most common type is blue/yellowThe second most common type is blue/yellow http://colorvisiontesting.com/http://colorvisiontesting.com/

ishihara.htm#plate%20with%207%20answerishihara.htm#plate%20with%207%20answer

http://www.webexhibits.org/causesofcolor/http://www.webexhibits.org/causesofcolor/2.html2.html

Audition (Hearing)Audition (Hearing)

Frequency-Number of wavelengths that pass a Frequency-Number of wavelengths that pass a point in a given timepoint in a given time

Pitch-determined by frequency of a sound Pitch-determined by frequency of a sound wavewave

Intensity-volume, determined by amplitude of Intensity-volume, determined by amplitude of a sound wavea sound wave

Decibels-measures volumeDecibels-measures volume

Parts of the EarParts of the Ear

Auditory Canal Auditory Canal EardrumEardrum Hammer Hammer Anvil Anvil StirrupStirrup Oval WindowOval Window Cochlea (lined with basilar membrane inside)Cochlea (lined with basilar membrane inside) Auditory nerveAuditory nerve

Theories about how we hear Theories about how we hear pitchpitch

Helmholtz Place TheoryHelmholtz Place Theory-pitch determined by -pitch determined by area of basilar membrane (covers the cochlea area of basilar membrane (covers the cochlea and covered with tiny hairs) that is stimulatedand covered with tiny hairs) that is stimulated

Frequency theoryFrequency theory- pitch is determined by the - pitch is determined by the frequency that the entire basilar membrane frequency that the entire basilar membrane vibrates at.vibrates at.

Hearing LossHearing Loss

Conduction Deafness-damage to an ear part Conduction Deafness-damage to an ear part prior to the cochleaprior to the cochlea

Nerve Deafness/sensorineural hearing loss-Nerve Deafness/sensorineural hearing loss-damage to cochlea or auditory nerve.damage to cochlea or auditory nerve.

Cutaneous/TouchCutaneous/Touch

The four main receptors are for The four main receptors are for cold, warm, cold, warm, pressure, and painpressure, and pain

The lips are one of the most sensitive areasThe lips are one of the most sensitive areas

Gate Control Pain TheoryGate Control Pain Theory

Pain travels up small nerve fibers to the spinal Pain travels up small nerve fibers to the spinal cord and then the braincord and then the brain

Pressure travels up large fibers to the spinal Pressure travels up large fibers to the spinal cord and then to the braincord and then to the brain

Pain and pressure can’t exist in the same spot Pain and pressure can’t exist in the same spot at the same timeat the same time

By activating pressure fibers By activating pressure fibers or through mental or through mental focusfocus, you can block pain signals, you can block pain signals

Taste/GustationTaste/Gustation

There are FIVE Taste sensation:There are FIVE Taste sensation: SweetSweet Sour Sour Salty Salty Bitter and…Bitter and… Umami!Umami!

Smell/olfactionSmell/olfaction

Receptors: located high in the nasal cavityReceptors: located high in the nasal cavity

Smelly FactsSmelly Facts

If your nose is at its best, you can tell the If your nose is at its best, you can tell the difference between 4000-10,000 smells!difference between 4000-10,000 smells!

Our sense of smell is really strongly connected Our sense of smell is really strongly connected to our memory and can trigger them suddenlyto our memory and can trigger them suddenly

Everyone has a unique smell except for Everyone has a unique smell except for identical twinsidentical twins

Women smell better than menWomen smell better than men

Top 20 most recognizable smellsTop 20 most recognizable smells

CoffeeCoffee Peanut butter Peanut butter Vicks VapoRubVicks VapoRub Chocolate Chocolate Wintergreen oil Wintergreen oil Baby powderBaby powder Cigarette buttsCigarette butts

Mothballs Mothballs Dry cat food Dry cat food BeerBeer Ivory bar soap Ivory bar soap Juicy FruitJuicy Fruit

Orange Orange Cinnamon Cinnamon LemonLemon Tuna Tuna Banana Banana Crayola Crayons Crayola Crayons Cheese Cheese BleachBleach

FlavorFlavor

Flavor is 70% smellFlavor is 70% smell One reason why hot foods often have more One reason why hot foods often have more

“taste” than cold foods is that they vaporize “taste” than cold foods is that they vaporize more: the vapors pass from the mouth upward more: the vapors pass from the mouth upward into the nasal passages and stimulate smell into the nasal passages and stimulate smell receptorsreceptors

PerceptionPerceptionAttentionAttention

awareness testawareness test Selective-focus on a small amount of stimuli at any Selective-focus on a small amount of stimuli at any

given momentgiven moment Cocktail party effect-we attend to one voice at timeCocktail party effect-we attend to one voice at time Change blindness-we sometimes do not notice Change blindness-we sometimes do not notice

changes in our environmentchanges in our environment http://www.youtube.com/watch?http://www.youtube.com/watch?

v=vBPG_OBgTWgv=vBPG_OBgTWg

Mueller-Lyre illusionMueller-Lyre illusion

Visual capture-vision dominates the other Visual capture-vision dominates the other sensessenses

http://www.youtube.com/watch?http://www.youtube.com/watch?v=nQlIQHc17DM&playnext=1&list=PL6A14v=nQlIQHc17DM&playnext=1&list=PL6A14CAED38AB85E3&index=12CAED38AB85E3&index=12

Perceptual OrganizationPerceptual Organization

Gestalt-seeing the parts Gestalt-seeing the parts as an organized wholeas an organized whole

Adcorcing to a reesarch at Caibrmdge Adcorcing to a reesarch at Caibrmdge Univeristy, it deosn't mttaer in waht oredr Univeristy, it deosn't mttaer in waht oredr the letters in a wrod are. The olny the letters in a wrod are. The olny iopmrtant tnihg is taht the frist and lsat iopmrtant tnihg is taht the frist and lsat letter be in the rihgt plcae.letter be in the rihgt plcae.

The rset can be a tatol mses and you can The rset can be a tatol mses and you can sitll raed it wihtout peoblrm. Tihs is sitll raed it wihtout peoblrm. Tihs is beuacse the hamun mnid deos not raed beuacse the hamun mnid deos not raed evrey letter by iestlf, but the wrod as a evrey letter by iestlf, but the wrod as a whloewhloe

Figure-ground perception-object/ground Figure-ground perception-object/ground environmentenvironment

Reversible figures-can flip object and Reversible figures-can flip object and background.background.

GroupingGrouping

Proximity: We group nearby objects togetherProximity: We group nearby objects together

SimilaritySimilarity

We group like objectsWe group like objects

ContinuityContinuity

We see things in the smoothest pattern We see things in the smoothest pattern possiblepossible

ClosureClosure

We tend to fill in the gaps in what we senseWe tend to fill in the gaps in what we sense

ConnectednessConnectedness

We see connected items as a group, even if We see connected items as a group, even if this overrides other Gestalt principles.this overrides other Gestalt principles.

Depth PerceptionDepth Perception

Visual cliff-experiment testing depth Visual cliff-experiment testing depth perception in babiesperception in babies

Binocular Cues-use two eyesBinocular Cues-use two eyes

1.1. Retinal disparity-compare images from two Retinal disparity-compare images from two eyes to perceive deptheyes to perceive depth

2.2. Convergence-the more “cross eyed” you are, Convergence-the more “cross eyed” you are, the closer something isthe closer something is

Monocular cues-use one eyeMonocular cues-use one eye

Examples:Examples: Light and shadowLight and shadow InterpositionInterposition TextureTexture Converging linesConverging lines

Motion perceptionMotion perception

Phi phenomenon- “moving lights”Phi phenomenon- “moving lights”

http://www.youtube.com/watch?http://www.youtube.com/watch?v=AMBiYKpMa5w&feature=relatedv=AMBiYKpMa5w&feature=related

Stroboscopic movement-see one picture after Stroboscopic movement-see one picture after another to create illusion of movementanother to create illusion of movement

http://www.youtube.com/watch?http://www.youtube.com/watch?v=gNYZH9kuaYMv=gNYZH9kuaYM

Perceptual constancy-Perceptual constancy- Size constancy-we perceive things as the same Size constancy-we perceive things as the same

size even when the image on our retina grows size even when the image on our retina grows or shrinksor shrinks

Shape constancy-we perceive shape as Shape constancy-we perceive shape as constant even when viewing objects from constant even when viewing objects from various anglesvarious angles

Color constancy- we perceive color as Color constancy- we perceive color as constant despite changing light levels (we constant despite changing light levels (we judge by surrounding colors)judge by surrounding colors)

http://www.youtube.com/watch?http://www.youtube.com/watch?v=TVUrHf2kcUMv=TVUrHf2kcUM