Myers PSYCHOLOGY Chapter 5 Sensation

Sensation and PerceptionSensationa process by which our sensory receptors and nervous system receive and interpret stimulus energyAfter receiving sensory information we must process it and this is perceptionPerceptiona process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and eventsSensation and perception blend into one continuous process

SensationBottom-Up Processinganalysis that begins with the sense receptors and works up to the brains integration of sensory informationDetects lines, angles, and colorsTop-Down Processinginformation processing guided by higher-level mental processesas when we construct perceptions drawing on our experience and expectationsInformation not form our senses, knowledge basedInterpretation

The Forest Has EyesOur sensory and perceptual processes work together to help us sort out complex processesBottom-up is the colors, lines, angles of the horses, rider and sourroundingsTop-down is the title of the painting and what will give the painting meaning

Sensation and Perception Cycle

ThresholdsWe live in a world on constant stimuliWhat do we notice and not notice?What do we feel and not feel?What do we sense and perceive?Psychophysics if the study of how physical energy relates to our psychological experienceWhat stimuli can we detect?At what intensity?How sensitive are we to changing stimulation

PsychophysicsPsychophysicsstudy of the relationship between physical characteristics of stimuli and our psychological experience of themLight- brightnessSound- volumePressure- weightTaste- sweetness

Sensation- ThresholdsAbsolute Threshold What we are super-sensitive too, even if the stimuli is faintEyelash on our face is one exampleAbsolute threshold is the minimum stimulation needed to detect a particular stimulus 50% of the time

Signal Detection TheorySignal Detection TheoryDetecting a weak stimuli depends on the signals strength but also on a psychological statepredicts how and when we detect a weak stimulus signalMeasured as ratio of hits to false alarmsWhy do people respond differently to same stimuliWhy does same persons reactions vary by circumstances? Why parents hear the slightest sound fro their baby, but miss louder sounds from other sourcesDetection depends partly on personsexperienceexpectationsmotivationlevel of fatigue

Subliminal!We have all heard of thisSubliminal messages can be both visual and auditorySubliminal means stimuli below our threshold that we unconsciously detect and perceiveRemember that absolute threshold is 50% of the time so yes we can be and are stimulated by things below that thresholdCan we feel what we do not know and cannot describe?Can we be manipulated using this?Psychologists say NO!When it appears that they do is it placebo effect?

Sensation- ThresholdsSubliminalWhen stimuli are below ones absolute threshold for conscious awareness

Sensation - ThresholdsDifference Threshold (aka JND just noticeable difference)minimum difference between two stimuli required for detection 50% of the timeIncreases with the magnitude of the stimulusWebers Law- to be perceived as different, two stimuli must differ by a constant minimum percentageStimuli must differ by a constant proportion not amount to be noticedlight intensity- 8% differenceweight- 2% differencetone frequency- 0.3% difference

Sensory AdaptationDiminished sensitivity as a consequence of constant stimulationExample you walk into a house and it smells, but an hour later you no longer notice the smell.You get used to it you adaptDiminishing sensitivity to unchanging stimulus

End Day 1

Day 2 Backmasking and Subliminal Clips and DiscussionPlay several clips on subliminal messages and backmaskingResponse: Students are to write a 2 paragraph response analyzing what they saw today (combined with Internet Research) and explain if subliminal and backmasking work.

Subliminal Commercials

End Day 2

VisionAmazing how does light become images?Transductionconversion of one form of energy to anotherStimulus energy becomes neural messagesStimulus input is light energyNot color that strikes the eyes, but electromagnetic energy that our visual system perceives as colorWe se only a mall part of the color spectrum2 parts of light help our sensory experience:1. Wavelength - the distance from the peak of one wave to the peak of the nextDetermines hue (color we experience)2. Intensity Amount of energy in the light wavesInfluences brightness

Vision- Physical Properties of Waves

The EyeLight enters the eye through the corneaLight bends to provide focusLight then passes through the pupilPupil is an adjustable opening in the center of the eye Pupil is regulated by the irisIris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil openingAdjusts light intake by dilating/constricting in response to intensity or even inner emotionsBehind the pupil is the lens

The Eye ContinuedLens focuses the incoming rays into an image on the eyes light sensitive back surfaceDoes this through the process of accommodation changing the curvature Retina contains the receptor rods and cones and layers of neurons that process the visual informationRods detect black, white and grey/peripheral and twilight visionCones function in daylight and well-lit conditions/fine detail/color sensationsFovea is the retinas central area of focus add where cones cluster aroundFovea has cones but no rods

Vision

VisionAcuity sharpness of visionCan be changed by slight variations in the shape of the eyeNearsightednessLight rays from distant objects focus in the front of the retinaCondition in which nearby objects are seen more clearly than distant objects FarsightednessThe image of near objects is focused behind retinaCondition in which faraway objects are seen more clearly than near objects

Vision

Normal Nearsighted Farsighted Vision Vision Vision

Retinas Reaction to LightOptic nerve- nerve that carries neural impulses from the eye to the brainBlind Spot- point at which the optic nerve leaves the eye, creating a blind spot because there are no receptor cells located thereFovea- central point in the retina, around which the eyes cones cluster

Vision- Receptors

Pathways from the Eyes to the Visual Cortex

Day 4 Vision in more detailKQLW ChartComplete 1st 2 columnsWhat I already know/learnedQuestions I have stillWatch videos (also on website for class)G:\Eye\030 How Eyes Work - An Introduction.mp4Start at 1:00 into the videoG:\Eye\032 Visual Processing in the Retina.mp4Start at 4:00 minutes into videoComplete column 3What I learned todayKQLW ChartComplete column 4What I still want to learn

Start Day 5

Visual Information ProcessingVisual information goes from the retina in the eye to the thalamus then to the brains visual cortex in the occipital lobe130 million rods and cones in the retinaTransmitted by the ganglion cellsGanglions axons make up the optic nerveRetinal cells are VERY sensitiveCan misfireEven pressure can trigger misfiresBrain interprets the misfires as light

Feature DetectionGanglion cells send signals to the visual cortexFeature detector neurons respond to a scenes specific featuresEdges, lines, angles and movementsVisual cortex passes information to other areas of the cortex that respond to more complex patterns

Vast Visual EncyclopediaCells that are distributed throughout the brainRespond to one stimulus but not anotherCalled supercellsFire only when cues trigger them tooEx: A goalie blocking a shot when they see the ball or puck coming or anticipate the direction it might come from

How the Brain PerceivesPerception combines sensory input with assumptions and expectationsIf you stare at the Necker cube, it changes every few secondsThis demonstrates that perception is shiftingBrain constructs varying perceptions

Parallel ProcessingOur brains process several things at onceDivides visual scene into dimensionsColor, depth, movement, and formOur perceptions are based on integration of all from all the processing that happened simultaneouslyDifferent areas of the brain process each part of the visual sceneDamage one area and certain parts of vision do not worki.e. pouring a drink into a class appears frozen cant see movement

Parallel Processing

Summary of Processing of Visual Information

Color VisionLight rays are NOT coloredColor is in our brains not in the object we seeThe brain manufactures colorTheory is that any color can be created by combining light waves of 3 colorsRed, green, and blueRetina only has 3 color receptors

Color-Deficient VisionPeople who suffer red-green blindness have trouble perceiving the number within the designThey have only 2 color receptors

Opponent-Process TheoryAfter leaving receptor cells, visual info is analyzed in terms of if the opponent colorsNeurons are turned on and off by certain colorsONOFFred greengreen red blue yellow yellow blue black whitewhite black

Opponent Process- Afterimage EffectWe get tired of our green response by staring at greenSo when we stare at the white (which contains all colors), we see only the red part of the red-green pairing

Color ConstancyPerceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the objectIn English we see common objects as the same color even though the wavelengths may actually change.

End Day 5

AuditionAuditionthe sense of hearingFrequencythe number of complete wavelengths that pass a point in a given timePitcha tones highness or lownessdepends on frequency

The Intensity of Some Common Sounds

Audition- The EarMiddle Earchamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochleas oval windowInner Earinnermost part of the ear, contining the cochlea, semicurcular canals, and vestibular sacsCochleacoiled, bony, fluid-filled tube in the inner ear through which

AuditionPlace Theorythe theory that links the pitch we hear with the place where the cochleas membrane is stimulatedFrequency Theorythe theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

How We Locate Sounds

AuditionConduction Hearing Losshearing loss caused by damage to the mechanical system that conducts sound waves to the cochleaNerve Hearing Losshearing loss caused by damage to the cochleas receptor cells or to the auditory nerve

AuditionOlder people tend to hear low frequencies well but suffer hearing loss for high frequencies

TouchSkin Sensationspressureonly skin sensation with identifiable receptorswarmthcoldpain

PainGate-Control Theorytheory that the spinal cord contains a neurological gate that blocks pain signals or allows them to pass on to the braingate opened by the activity of pain signals traveling up small nerve fibers gate closed by activity in larger fibers or by information coming from the brain

TasteTaste SensationssweetsoursaltybitterSensory Interactionthe principle that one sense may influence anotheras when the smell of food influences its taste

Smell

Age, Sex and Sense of Smell

Body Position and MovementKinesthesisthe system for sensing the position and movement of individual body partsVestibular Sensethe sense of body movement and positionincluding the sense of balance

Complete 5.1 prior to beginning5.2 Top Pictureto show the difference between sensation and perception. Looks like a meaningless blotch, students will try to figure it outstimulation/sensation is being received but not perceived. The subject is a dog, and only part of a dog. Students will probably try to see the whole dog; you cannot tell figure from ground5.2 Bottom pictureFraser Spiralit looks like a spiral but is actually a set of concentric circlesTop Down is the involvement of the brain in making meaning out of stimuli. For example there are people who can see everything clearly (sensation) but cannot recognize even their own faces (perception).Placing meaning to sensations and stimuli is the act of perceptionThe Forest Has Eyes is the title of this work---in studying it we look at the expressions on the faces, there is something foreboding about this picture, and after we have read the title we notice other thingsThree methods to testMethod of Limits: begin with a minimal stimulus and increase until it is perceived by subjectMethod of right and wrong cases: subject sees identical stimuli repeatedly and says yes if perceives them or it they are different, and no if not perceived or the two are not differentinforms how likely it is that any given stimulus level or difference between stimuli will be perceived by subject.Method of adjustmentadjust a comparison stimulus until it appears to be identical to the standard stimulus, errors occur and are noted then averaged to give a measure of jndTry the timer in the kitchenput it in a quiet room, move away and then move backthe point at which the ticking is perceived is the absolute threshold, at that point they may be able to hear sometimes and others time not, needing to move a few feet one way or the otherlapses of attention, fatigue other factors influenceLay audiences accept the idea of subliminal persuasion but it has not been substantiated in research

Try the following experiment: two envelopes, one with two quarters in it, the subject will be able to tell the difference, but then put the envelopes in a pair of shoes and try to tell the differenceWeber's Principle: difference thresholds grow with the magnitude of the stimulusIf you make $5 p/h a 25 cent hour raise will be noticeable but at $10 p/h you may need 50 cents.If you are in sales, three piece suit and sweater, sell the suit first because after the suit the man will be more likely to buyIn car sales, after the sale customer wont really notice $500 stereoADAPTationhabituationAfter drinking tea with lemon, a grapefruit will not taste as sourbut after a roll, it will taste especially sourAfter holding salty water in mouth, it will taste less salty, and drinking fresh water afterwards, it will taste sweetThe blind spot occurs is the location in the retina where the visual cortex exits to the brain, there are no receptors thereWhat our brain does, typically, is fill in that missing piece based on what it estimates to be thereBlindsightwe can see things we dont perceiveRetinal ganglion cells---go back to 5.3 and then to 5.45.4a is the cover of a catalog and students complained of seeing gray spotsThe grid pattern is called the Hermann grid after the German physiologist who first discovered itThe elusive gray spots can be explained in terms of the receptive fields of the retinal ganglion cellsSome of the cells are an on center surrounded by an off (like a donut). Light has opposite, antagonistic effects 5.7 is an initial test for color blindness, students with scores above 16 have an 81 percent chance of failing a standard screening for color vision8 percent of males, .05 percent of females show color weaknessesColor defects are genetically transmitted, recent research has conclusively mapped this transmissionMonochromatshave no or only one type of functioning cone type and respond to light like a black and white filmcolors are records only as gradations of intensity, likely to find daylight uncomfortable if no functioning cones, those with one cone okay but still cant discriminate colorsvery small number of people have thisDichromatsone malfunctioning cone system, depending on type, various colors will not be perceived, inability to perceive blue is the rarest, in 1950 England, found 17 people5.9shows that colors can be subjective, no wavelengths of lightLook in the center of this and many people will see wavy patterns of pastel , because the eye is constantly moving and these movements displace the image of the diagonal lines over the retinal receptors and create a pattern of receptor activity that typically occurs from viewing colored stimuliA recent U of Tenn. study found that 60 percent of college students suffer some high-frequency hearing lossLoud music is believed to be the culpritLive concerts120 + decibels, louder than jack hammer, chainsawOSHA says that 85 decibels (food processor) 8 hours, 5 days a week will eventually cause permanent hearing lossFor each 5 decibel increase, the time it takes to cause lasting injury drops by half

Try: hold finger up as if taking a court room oath, rub thumb, finger together and should hear a scrtiching sound---if not, MAY have hearing lossExperimenthave someone sit in front of class with eyes closed. Clap hands around head and ask student to identify where the sound comes fromwill be able to do so when the sounds come from one side or the other, but less clearly able to do so when the sounds overhead in back or in front

The perceived difference in sounds is related to the time at which the sound is receivedRinging in the ears is called tinnitus, affects more than 36 million AmericansMost common cause is exposure to loud noises, but also can be caused by certain drugs, ear infections, food allergiesIn most severe form, this ailment is incapacitatingTouch localization demonstration, concentrate on where the sensations of touch are felt:Touch two index fingers together, feel it in bothTouch finger to bottom lip, light taps, felt mostly in lip even though both are being stimulatedTouch ankle, now its felt mostly in fingerTouch localization depends on the relative lengths of the pathways from the stimulated parts to the brainPain is an important signal to our bodiesThe experience of pain can be influenced by information from the brainChronic painest. that over 100 million people suffer from thisOne study had teen age burn patients undergo a few minutes of wound treatment while they played Nintendo or while they were in a virtual reality environmentthe patients felt less pain and spent less time thinking about their pain in virtual reality than Nintendo due to concept of presencesillusion of going inside another world. Pain requires attentionSome taste sensations are genetically programmed, such as sweet, and finding bitter and sour foods unpleasantA study of babies had sweet eliciting smiles, lip smacking, and sour eliciting protrusion of tongueThese reactions make good evolutionary senseAnimals tend to be neophobic, and human children are reluctant to try new thingsOne experiment asked a group of subjects to taste two groups of food (that were the same). When the items were accurately named (chopped tomatoes, oatmeal, beefsteak) more willing them when given novel names (pendula fruit, lat, langua steak)However, as true with other stimuli , mere exposure makes us like them moreSmell can be used to identify genderThe phenomenon of women in the same home having the same menstrual cycle is related to smellresearcher Martha McClintock discovered this 30 years ago while at Wellesley College; now a researcher at the U of Chicago found that smell can stimulate ovulationCitrus odors make people more alert, spiced apple helps relaxationPumping certain pleasant food odors cut by 40 percent shoving, pushing in New York subwaysPeople in New York mall were more likely to help strangers when there was the aroma of roasting coffee or baking cookiesGood and Plenty licorice combined with cucumber increased female blood flow by 14 percent (anything over 10 percent was considered stimulating), baby talc 13 percent, lavender + pumpkin pie 11 percentCherry cut flow by 18 percent, charcoal barbecue 15 percent, mens cologne by 1 percentWomen seem to be excited by things that remind them of childhood, or are fresh smelling, relating to safety and security needed in order to feel sexual

Ian Waterman, after viral infection, lost his sense of light touch and body position and movementcan walk but must look at limbs to direct themWhen lights go out, he falls and cannot get up again until they come back onWhen he is not looking at his body, he moves very little, unlike most of us who move around quite a bit

Synesthesiasensory condition in which stimulating one modality leads to perception in another (to perceive together)1 in 2,000 occurrence, females outnumber 6 to 1, seems to run in families so there may be a genetic base