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1. Chapter 5 Sensation and Reality Properties of Sensory Systems Eyes (vision)= light sensory system Senses Sensitivity to senses Vision Perception of color Hearing mechanism Chemical senses What do the senses have in common? Data Reduction System (DRS) Sensory images or other senses us DRS DRS= 1. Selects 2. Analyzes 3. Filters information until only important details remain. Transducers= device that changes one kind of energy to another Sense are receptive to Range of Energy We only perceive some forms of energy (example- specific types of wave) Sensory AnalysisAs senses process info… The senses divide the world into important Perceptual Features Which are Basic stimulus patterns Example: Vision – Features include- Lines shapes, edges, spots and colors DRS 1. Select 2. Analyze 3. Filter When a pattern is broken the senses recognize the features Perceptual Features- Pop Out when a pattern is present /////i///// ////////// ///////// Analysis (part of Data Reduction) Sensory Analysis 1st Senses use – Feature detectors- detect patterns Code it – After sense info is analyzed It is converted into Neural Messages understood by the brain (AKA Transduction) Phosephenes = visual sensations- caused by mechanical stimulation of retina) Eye’s receptor cells are sensitive to pressure as well as light Sensory Localization = (means) types of sensations you experience depends on which brain area is activated- (Vision , Auditory, taste, touch) Sense Organs Eyes, Ears- info creates Sensations Perception takes place in Brain (patters = Perceptions) Psycho-PhysicsMeasures of physical stimuli Q: What’s the minimum amount of energy necessary for sensation to occur? A: Absolute Threshold Absolute Threshold Thresholds define limits of sensory world *Sensation = immediate response in the brain Dog whistles = upwards of 40,000 hertz (Beyond Human awareness) Humans senses from 20 Hertz = Vibrations per second To 20,000 Hertz Difference Thresholds Q: How much must a stimulus change before it is noticeably different? JND= Just Noticeable Difference The smallest difference between stimuli that we can detect is called JND. Weber’s Law- The amount of change needed to produce JND is a constant proportion of the original stimulus. “That's to say that, if the intensity of a sensation (of sight, or smell, or sound, or taste, or touch) is doubled from an initial value and the sensation noted, the intensity will have to be doubled once more to give the same impression of increase in sensation.” Sensitivity to hearing /Pitch/Loudness is greater than taste Perceptual Defense & Subliminal Perception Thresholds vary for different people & could change Perceptual DefenseThe resistance to perceiving threatening or disturbing stimuli The McGinnies study- (1994) Dirty words take longer to be recognized. Seems that we resist info that causes Anxiety, discomfort, or embarrassment. Limen (Threshold or Limit) for awareness Below the normal Threshold = Subliminal Subliminal Perception Demonstrated by insertion of images, Emotional Images caused altered impressions Too fast to be recognized Below the level of conscious awareness Subliminal Persuasion- Selling Popcorn and Coke at movies… (Author says it doesn’t work) Rock Music and Subliminal Messages Back Masking- perceived unconsciously (Vokey and Read 1985 said no effect) Subliminal Perception does occur “Subliminal effects are usually small and short-lived, and they mainly affect simple judgments and general measures of overall arousal.” Messages that people can perceive consciously have far stronger persuasive effects. Vision: Catching Some RaysWavelengths of light = Visible Spectrum “Electro magnetic energies to which the eyes respond” Visible Light Starts @400 nano meters =One billionth of a meter =Purple or violet Longer Light waves = Blue, Green, yellow, orange, and red =700 nanometers Hue= Basic color categories – red orange yellow, green, blue, indigo, violet Corresponds to light’s wavelengths Saturation= pure color = narrow band of light Brightness= amplitude, height of light waves Taller more energy, more color, brighter more intense Structure of the Eye: Eye is like a Camera Lens to focus images on a light sensitive layer at back of a closed space Back layer is= a layer of photo receptors in retina- (light sensitive cells) Focus is done at front of eye via the Cornea Cornea = clear membrane, bends light inward Lens – makes small adjustments – Shape is altered by muscles for focus Muscles use Accommodation- change Camera’s change distance from film http://www.eye-floaters.com/theeye-nearandfarvision.php problem is the shape of cornea and how it is projected onto the back of the eyeball or retina Astigmatic Near Sighted Myopic= Longer (than usual) eye Concave lens-spreads light rays just enough to increase eyes focal length FarsightedThe convex lens increases refraction (bending) Returns point of focus to Retina. Astigmatic: (lens) or Cornea not symmetrical) eye parts of vision are sharp And parts are unfocused Lens is Unsymmetrical Visual Problems Presbyopia Old vision Lens becomes less flexible Farsightedness to aging Focusing is affected by the shape of the eye Hyperopia – (Farsightedness= eye is too short) Can’t focus nearby objects- trouble reading up close Distant objects will be sharp Myopia- (nearsightedness) eyeball is too long Images fall short of the retina Can’t focus on distant objects Close objects are in focus Astigmatism- Cornea lens is misshapen Part of vision is focus Part is also fuzzy Eye has more than one focal point All are corrected by lenses that change the path of light LASIK- Lasor Assisted Insitu keratomileusis Reshapes and stretches the cornea Increases degree of cornea bending light Light ControlThe Iris- controls amount of light entering Colored – Muscle that expands and contracts Changes size of pupil Allows more light Dilates= enlarged pupil- allows more light Constrict= narrow less light enters the pupil Anatomy of the Eye Retina Vitreous Humor- Jelly like substance Fills the eyeball Photoreceptor cells Rods Cones Fibers of Optic Nerve Ganglion Cell Amacrine Cell Bipolar Neuron Horizontal Cell Anatomy of Eye Optic Nerve Retinal Arteries Retinal Veins Retina Lens Blind Spot Fovea Ciliary Muscle Aqueous Humor Iris Cornea Vitreous Humor Sclera Page 183 “How the Brain Sees the World” David Hubel and Torstem Wiesel Say- Vision Acts more like a computer than T.V. Recorded cell activity In Brain’s visual cortex (cats & monkey subjects) Noted area of retina where cells responded Collected data on light & firing of nerve impulses Found cells in the brain act as Feature Detectors Process- the brain analyzes info into lines, angles, shading, movement… Then- other brain areas combine Features into meaningful visual experiences. Rods and Cones: Light does not fall on rods and cones it must pass layers of retina/ Receptor cells Rods Cones 100 million each eye 6.5 million in each eye No Color Work best in bright light Black and White = Pure Rod Vision Color Sensations More Sensitive to light than cones Fine Detail Allows sight in dim light Mostly at center of eye Sensitive to movement Fovea contains only cones Good for Peripheral Vision Most sensitive to yellow, green color Contain light sensitive visual pigments (Theory Tri-color) 3 types of cones- Fire nerve impulse@ different rates to produce color Break down when struck by light sensations After image of Flash bulbs= “Bleading” Night Vision- Rod Pigment= increase Rhodopsin- Vitamin A enhances Retinal sensitivity (see link) Each eye has a Blind spot Where optic nerve leaves the eye <no receptors> Visual Acuity = Sharpness Normal 20/20 20’ distance you can see what average people see at 20 ft. 20/40 = you can only see at 20 feet what most people see at 40 feet 20/200 = correct= legal blindness FoveaCup shape on retina Only has cones Concentration of cones = greatest visual acuity Pixel Dot of light More pixels = sharper image Peripheral Vision: “Rod Vision” – not very sharp Area outside the Fovea gets light Side visionRods most numerous ca (around) 20° from center of retina Tunnel Vision = Loss of peripheral vision Color Vision Yellow-green spectrum Cones most sensitive Rods not sensitive to color but colored light- blue green is most sensitive At night blue can be seen best Color Theories= Tri-chromatic Theory = what happens in the eye 3 types of cones Each sensitive to red green blue Other colors are combos Problem There are 4 colors of light- Red, Green, Blue, Yellow You can get these by mixing Doesent Address all aspects of colored light Opponent Process Theory: Vision analyzes color as either or messages Red or green Yellow or Blue System can produce either Black or white Explains what happens – Optic pathways + Brain After info leaves Brain How colors are analyzed – after eye ball After Images Visual sensations that persist after stimulus is removed “Seeing spots” Relates to Opponent Process TheoryFatigue caused by one response causes after image of opposite color system Bothe theories apply Tri-color 3 visuals Pigments= light sensitive chemicals Red, Green, or Blue 3 types of cones- Fire nerve impulse@ different rates to produce color sensations Mechanical View of Color Sensation Colors are influenced in the brain by other colors nearby = Simultaneous color contrast Affect perception of color (p 186) Color Blindness Can not perceive colors Lacks cones or cones don’t function Rare Color Weakness= people can’t see certain colors 8% of males = red – green weakness (see red and green as yellow – brown) 1% of women Genetic Affecting Red and Green + Blue Pigments in Cones Ishihara- Test – I.D.s Color Blindness Contrasts- colors through simple patterns circles/squares Light and Dark Adaptation (Rods) The dramatic increase in retinal sensitivity Eyes adjust- 30-35 minutes for maximum sensitivity Complete darkness = 100,000 times more sensitive Contain light sensitive visual pigments Night Vision- Rod Pigment= increase Rhodopsin- Vitamin A enhances Retinal sensitivity Break down when struck by light After image of Flash bulbs= “Bleading” Red light- helps people adapt to dark- it doesn’t stimulate rods It doesn’t stimulate the rods As the retinal component of rhodopsin is derived from vitamin A, a deficiency of vitamin A causes a deficit in the pigment needed by rod cells. Consequently, fewer rod cells are able to sufficiently respond in darker conditions, and as the cone cells are poorly adapted for sight in the dark, blindness can result. This is nightblindness. Hearing: “Good Vibrations” Hearing- Collects info Stimulus for hearing = waves in air Peaks – Compression Valley’s = Rarefaction Sound waves = vibrating objects Rhythmic = movement of air molecules Sound does not travel in a Vacuum Frequency of Sound Waves = # of waves per second Corresponds to pitch (the tone of a sound) Amplitude= height of a sound wave Tells how much energy it contains Relates to loudness (sound intensity) Sound waves converted to Nerve Impulse Pinna (visible, external part of ear) Acts as a funnel to concentrate sound Tympanic Membrane (eardrum) Sound waves collide Auditory Ossicles (3 small bones) link eardrum to cochlea= Snail shape organ Vibrate 1. Malleus- hammer Links eardrum with Cochlea 2. Incus- Anvil 3. Stapes- Stirrup-- Oval windowTo cochlea- is organ of hearing- inside tiny hair cells = Sterocilia detects waves in fluid To cochlea- is organ of hearing- inside tiny hair cells = Sterocilia detects waves in fluid Part of Corti- (center of cochlea) Steriocilia: Hair cells brush against the Tectorial Membrane when waves ripple through the fluid surrounding the organ of Corti. Then to the Auditory nerve fibers- Frequency Theory- of Hearing As pitch rises Nerve impulses of same Frequency are fed to auditory Nerve Example – 800 hertz (= number of vibrations per second)- tone = 800 nerve impulses Place TheoryHigher & lower tones excite specific areas of the Cochlea High tones at the base of Cochlea Low tones move hair cells near outer tip of Cochlea Hair Cells respond to area of greatest movement Deafness- 2 types of deafness Conduction Deafness = Transfer vibration to inner ear is weak Eardrum or Ossicles are damaged Hearing Aid- makes sounds clearer + louder Stimulation (deafness) Loud sounds (Damage Hairs) 85 Decibels- may cause permanent loss Temp-Threshold Shift 120 decibels Partial transitory hearing loss Nerve deafness= damage to hair-cells or auditory nerve Tinnitus- ringing- buzzing sensation Sense of Smell and Taste: Olfaction (Smell) Gustation (Taste) Chemical Senses receptors that respond to chemical molecules Olfactory Receptors: Receptors- Airborne molecules 300-400 smell receptors Thread like fibers inside nose 5 million nerve fibers Upper nasal passages Receptor Proteins- are sensitive to molecular stimulation Combination of Odor receptorsCan detect 10,000 different odors in humans “Lock and Key Theory” Shape of receptors impact smells Also Location of receptors Number of activated receptors tells how strong an odor is. Anosmia- Anosmic (no sense of smell) Defective smell For single odor Suggest these are specific receptors for specific odors Molecularly- some odors have similar shape Sent likes and dislikes are learned Pheromones- “A Sixth Sense” Animals – affected Mating Sexual Behavior Recognition of Family members Territorial marking Vomeronasal Organ- (VNO) The sense organ for pheromones Receptors in septum Produces vague feelings Well being Attraction Unease Anxiety Affect General Mood May cause women’s menstrual cycles to become synchronized Taste: 4 basic Taste Sensations Sweet Least Sensitive SaltSourBitter- Most sensitive Flavor Taste buds= taste receptors cells Top of tongue and around the edges Chewing- taste buds nerve impulses to brain Lock and Key matching Sour = Saltiness triggered by direct flow of atoms Taste-Sensitivity = how many taste buds on tongue Age association Cells live only days then are replaced Taste preferences are acquired Somoesthetic Senses- Body Feel 1. Touch Skin senses Pain Balance 2. Kinesthetic Senses (movement) Receptors in muscles Receptors in Joints Detect body position + Movement 3. Vestibular Senses Receptors in the inner Ear for balance, gravity, Acceleration Skin 5 Sensations Light + touch Pressure Pain Cold Warmth Receptors- shape specialize Skin has 200,000 nerve endings for temperature 500,000 touch + pressure receptors 3 million for pain # of skin receptors = skin receptivity Increased Density of receptors in: Lips Tongue Hands Genitals Pain- (Warning System- says the body is being damaged) Lots of Pain Receptors Varied Distribution 232 Pain points per 5 square centimeters (behind knee) 184 in Buttocks 60 in the thumb 44 on nose Pain fibers are also on internal organs Visceral Pain is felt on the surface of the body = Referred Pain Somatic Pain (Bodily) 2 types 1. Large nerve fibers Skin, Muscles, Joints, Tendons Sharp bright and fast From specific body areas Warning System- says the body is being damaged 2. Small Nerve Fibers Slower, nagging, aching, widespread, very unpleasant Repeat is more painful Reminder System Reminds brain that the body has been injured Phantoms Live Here Missing limb continues to feel as if it is present Brain still senses limb Brain can reorganize the senses Dynamic TouchArcs Sensation from skin + Kinesthetic info from muscles + Tendons We can use objects like extension of our bodies Vestibular System Inner Ear Motion Sickness Semi-circular canals Sense organs-for balance Semi Circular Canals Sense organs for balance, filled with fluid Ampullae- contains crista and fiber