Chapter 3: Sensation and Perception
Chapter 3: Sensation and Perception 42829 - PSY 121 - 003
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This 13 page Class Notes was uploaded by Heather Caffey on Monday October 5, 2015. The Class Notes belongs to 42829 - PSY 121 - 003 at Missouri State University taught by Christie L Cathey in Fall 2015. Since its upload, it has received 116 views. For similar materials see Introductory Psychology in Psychlogy at Missouri State University.
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Date Created: 10/05/15
Chapter 3 Sensation and Perception I The ABCS of Sensation a What is Sensation 1 Sensation special receptors in special organs are activated allowing various forms of outside stimuli to become neural signals in the brain 2 Transduction 0 process of converting outside stimuli into neural activity ii Sensory Receptors 1 Specialized forms of neurons cells that make up the nervous system 2 Stimulated by energy other than other neurotransmitters 3 Electric information is either depolarized or hyperpolarized causing the cell to re more or less based on timing and intensity of the information from the environment iii Sensory Thresholds 1 Weber39s Law ofJust Noticeable Differences Just Noticeable Difference or Difference Threshold a Smallest difference between two stimuli that is detectable fty percent of the time b Means that whatever difference between stimuli might be it is always a constant 2 Absolute Threshold Gustav Fechner a Lowest level of stimulation that a person can consciously detect fty percent of the time that the stimulus is present 3 Subliminal Stimuli stimuli that are below the level of conscious awareness a Subliminal perception b EvenRelated Potentials ERPs and fMRI used to verify existence of subliminal perception and associated learning in laboratories b Habituation and Sensory Adaptation 1 Habituation way that brain deals with unchanging information from the environment 2 Sensory Adaptation process by which constant unchanging information form sensory receptors is effectively ignored 3 MicrosaccaclesSaccadic Movements eyes are always moving II The Science of Seeing a Light and the Eye 1 ii Light 1 2 3 Photons quotwave pocketsquot Three aspects to perception of light brightness color saturation Brightness determined by the amplitude of the wave a Higherbrighter lowerdimmer Color Hue determined by length of the wave a Short wavelengths found at blue end of the visible spectrum b Long wavelengths found at the red end c Visible Spectrum portion of whole spectrum of light that is visible to the human eye d Saturation refers to the purity of color iii The Structure of the Eye 1 2 3 Visual Light enters eye directly from the source or indirectly re ection To see clearly a single point of light must end up on retina as a single point Refraction light bends as it passes through substances of different densities Cornea clear membrane that covers the surface of the eye a Protects and focuses most of the light coming into the eye b Photoreactive Keratectory PRK and laserassisted in site keratomileusis LASIK Aqueas Humor clear watery uid a Continually replenished and supplies nourishment to the eye PupHandl s a Pupil hole in the eye b lris colored part of the eye and lets in more or less light Lens a Suspended by muscles b Clear structure that nishes the focusing process Accommodation process where lens changes its shape from thick to thin enabling it to focus on objects close or far away a Presbyopia lens hardening as one ages b Myopia nearsightedness light falls short of the retina c Hyperopia farsightedness light focuses behind the retina Vitreous Humor clear jellylike uid a Nourishes eye and gives it shape 10Retina light sensitive area of back of the eye containing three layers ganglion cells bipolar cells and rods and cones a Rods and Cones photoreceptors that respond to various wavelengths of light b Cones more concentrated in lovea i Require more light than rods and work best in bright light ii Responsible for color vision c Rods i Concentrated in periphery and responsible for periphery vision ii Sensitive to changes in brightness but only narrow band of wavelengths 11Blind Spot area in the eye that has no rods or cones iv How the Eye works 1 Light travels in straight line through cornea and lens resulting in upsidedown image and reversed from left to right Temporal Retinas axons project to visual cortex in same side of the brain Nasal Retinas axons cross over to visual cortex on opposite side of the brain a Optic Chiasm point of crossing Dark Adaptation occurs as eye recovers its ability to see when going from a brightlylit state to a dark state a Bright the light the longer the adaptation Light Adaptation occurs as the eyes goes from a dark state to a brightlylit one a Faster than Dark Adaptation b Perception of Color i Trichromatic Theory 1 2 3 4 5 6 Thomas Young in 1802 and modi ed by Hermann von Helmholtz 1852 Proposed three types of cones one each for primary red blue green Different shades of colors correspond to different amounts of light received by each of three types of cones Combination of cones and the rate at which they re is what determines color Short wavelength cones detect blueviolet medium green long greenyellow Each cone responds to light across the range of wavelengths ii Opponent Process Theory 1 Afterimages occur when visual sensation persists for a brief time after original stimulus is removed Edwald Hering in 1874 Four Primary Colors red green blue yellow a Red paired with green blue paired with yellow 4 Some neurons are stimulated by light from one part of the spectrum and inhibited by the light from another part of the spectrum 5 Trichromatic Theory can explain what is happening with raw stimuli 6 OpponentProcess Theory can explain afterimages and other aspects of visual perception that occur after initial detection of light from the environment 7 Opponent Processing cells contained inside the thalamus in lateral geniculate nucleus LGN a LGN is part of pathway that visual information takes to the occipital lobe i When cones in retina send signals through the retinal bipolar and ganglion cells 8 LGN cells and retinal cells appear to be responsible for opponent processing of color vision and afterimage effect iii Color Blindness 1 General term caused by defective cones in retina of the eye 2 Colorde cient vision is more accurate 3 Three kinds of color de cient vision a Monochrome color blindness i Very rare ii No cones of have cones that are not working b Dichromatic vision i Having one type of cone that does not work properly 4 Sexlinked inheritance a Gene for color de cient vision is recessive b Gene for color de cient vision is attached to a particular chromosome that helps to determine sex of the person c More males than females have color de cient vision Ill The Hearing Sense Can You Hear Me Now a Sound waves and the Ear 1 Vibrations of the molecules of air that surround us a Wavelengths frequency or pitch b Amplitude volume c Timbre richness in tone of sound 2 Frequency is measured in Hertz Hz cycleswaves per second ii The Structure of the Ear Follow the Vibes 1 The Outer Ear UJN a b Pinna visible external part of ear that funnels sound waves into structure of the ear also entrance to auditory canal Auditory CanalEar Canal short tunnel that runs down to the tympanic membrane eardrum 2 The Middle Ear a b C d Three tiny bones known as hammer malkus anvil incus and stirrup stapes Collectively referred to as the ossicles smallest bones in the body Vibration of bones ampli es vibrations from the eardrums Stirrup causes membrane covering opening of the inner ear to vibrate 3 The Inner Ear a an g b Perceiving Pitch 1 Pitch Membrane covering inner ear is called the oval window i Vibrations set off chain reaction Inner ear cochlea snailshaped structure lled with uid Fluid surrounds basilar membrane Basilar membrane is resting place of organ of Corti Organ of Corti contains receptor cells for sense of hearing which are hair cells Auditory Nerve contains axons of all receptor neurons Louder the sound the stronger the vibration how high or low a sound is 2 Three primary theories about how the brain receives information about pitch a b C Place theory i Oldest theory ii Hermann von Holtz 1865 and George von B k sy 1928 iii Pitch heard is dependent on where hair cells that are stimulated or located on Organ of Corti Frequency Theory i Ernest Rutherford 1886 ii Pitch is related to how fast the basilar membrane vibrates Volley Principle i Ernest Wever and Charles Bray ii Groups of auditory neurons take turns volleying c Types of Hearing Impairments 1 Hearing Impairment used to refer to dif culties in hea ng 2 Conduction Hearing ImpairmentConductive Hearing Loss a Problems with mechanics of outer or middle ear and means that sound vibrations cannot be passed from eardrum to cochlea b Cause might be damaged eardrum damage to middle ear 3 Nerve Hearing ImpairmentSensorineural Hearing Loss a Problem lies either in inner ear or in auditory pathways and cortical areas of the brain b Most common type of permanent hearing loss c Normal aging causes loss of hair cells and exposure to loud noises can damage hair cells d Cochlear implant IV Chemical Senses t Tastes Good and Smells Even Better a Gustation How We Taste the World i Taste Buds 1 Common name for receptor taste ces special kinds of neurons found in mouth that are responsible for gestation sense of taste 2 How sensitive people39s tastes are dependent on how many taste buds they have 3 Papiae bumps on tongue that are surrounded by the taste buds a Each one has about ten receptors 4 Taste receptors have to be replaced every ten to fourteen days ii The Five Basic Tastes 1 1916 Hans Henning four primary tastes sweet salty sour bitter 2 1966 Lindemann fth taste umami quotbrothyquot 3 All taste sensations are processed all over the tongue 4 Taste information sent to the gustatory cortex found in the front part of the insula and frontal operculum a Involved in conscious perception of taste whereas texture is processed in somatosensory cortex of parietal lobe 5 Cortical taste areas also project to parts of the imbic system b The Sense of Scents Olfaction i Olfactory Receptor Cells 1 Each have half dozen colia that project into the cavity 2 Olfactory receptors have to be replaced every ve to eight weeks 3 At least 1000 types of olfactory receptors ii The Olfactory Bulbs 1 2 3 Located right on top of sinus cavity on each side of the brain directly beneath the frontal lobes Bypass the thalamus when olfactory receptors send up information Send information to higher cortical areas including primary olfactory cortex piriform cortex orbitofrontal cortex and amygdale V Somesthetic Senses What the Body Knows 1 Somesthetic sense body senses b Perception of Touch Pressure Temperature and Pain 1 Skin Senses special receptors in skin39s layers that collect information ii Types of Sensory Receptors in the Skin 1 2 Pacinian Muscles just beneath the skin and respond to pressure Free Nerve Endings just beneath uppermost layer of the skin and responds to changes in temperature pressure and pain 3 Visceral Pain pain and pressure in the organs 4 Somatic Pain pain in skin muscles tendons and joints are carried on large nerve bers a Tends to be sharp and fast b Another type is slower and more of a general ache iii Pain Disorders 1 2 Congenital Analgesia and Congenital lnsensitivity to Pain With Anhidrosis CIPA born without ability to feel pain a Affect neural pathways that carry pain heat and cold sensations Phantom Limb Pain occurs when person who has had a limb removed sometimes quotfeelquot pain on missing limb iv Pain GateControl Theory 1 2 3 First proposed by Ronal Melzack and Patrick Wall 1965 and later re ned and expanded Pain signals must pass through quotgatequot located in spinal cord Activity of gate can be closed by nonpain signals coming into spinal cord from body and signals coming from the brain Gate represents relative balance in neural activity of cells in spinal cord that receive information from body then send to brain Substance P neuromodulator released by stimulation of pain receptor cells a Released into spinal cord activates other neurons that send messages through spinal gates b Message goes from spinal cord to brain activating cells in thalamus somatosensory cortex areas of frontal lobes and limbic system 6 Decision by brain to heighten or lessen pain is in uenced by psychological aspects of paincausing stimulus 7 Pain can also be affected by competing signals from other skin senses 8 Endorphins can inhibit transmission of pain signals in brain and in spinal cord can inhibit release of Substance P c The Kinesthetic and Vestibular Sense 1 Kinesthetic having to do with location of body parts in relation to each other 2 Vestibular 0 having to do with the movement and body position ii The Kinesthetic Sense 1 Proprioceptors tell you about joint movement or muscles stretchingcontracting 2 Kinesthesia sense of movement and location of body parts related to one iii The Vestibular Sense 1 The sense of balance 2 Structures for this sense are located in innermost chamber of the ear 3 Ofolith organs a Tiny sacs found just above the cochlea that contain gelatinlike uid within which tiny crystals are suspended b Tells person how heshe is moving 4 Semicircular Canals a Three semicircular tubes lled with uid that stimulate hair like receptors when rotated b Allows one to be located in each of three planes of motion 5 Motion Sickness disagreement between what eyes say and what body sees a Tendency to get nauseated when in a moving vehicle 6 Sensory Con ict Theory information from eyes con ict too much with the vestibular organs and dizziness nausea and disorientation are the results VI The ABCs of Perception 1 Perception method by which the brain takes all sensations people experience at any given moment and allows them to be interpreted in the same meaningful fashion b How We Organize Our Perceptions i The Constancies Size Shape and Brightness 1 Size Constancy tendency to interpret an object as always being the same size regardless of its distance from the viewer Shape Constancy tendency to interpret shape of an object as constant even when it changes on the retina Brightness Constancy tendency to perceive apparent brightness of an object as the same even when light conditions change ii The Gestalt Principles 1 Figure Ground Relationships a quotNecker Cubequot drawing of a cube with con icting sets of depth cues b Refer to the tendency to perceive objects or gures as existing on a background Reversible Figures gure and ground seem to switch back and forth Proximity quotnearnessquot tendency to perceive objects that are close to one another as part of the same grouping Closure tendency to complete gures that are incomplete Continuity tendency to perceive things as simply as possible with continuous patterns rather than a complex brokenup pattern Contiguity tendency to perceive two things that happen close together in time as being related Common region Stephen Palmer tendency is to perceive objects that are in a common arearegion as being in a group c Depth Perception 1 2 3 Capability to see the world in 3D Monocular cues require use of one eye Binocular Cues result of slightly different visual patterns that exist when visual elds of both eyes are used ii Monocular Cues 1 2 3 AKA quotpictorial depth cuesquot artists can use these cues to give illusion of depth to paintings and drawings Linear Perspective tendency for lines that are actually parallel seem to converge on each other Relative Size objects that people expect to be of a certain size appear to be small and are therefore assumed to be much further away Overlap if one object seems to be blocking another object people assume that blocked object is behind the rst and is therefore further away Aerial Atmospheric Perspective the farther away an object is the hazier the object will appear to be due to tiny particles of dust dirt and other pollutants in the air 6 Texture Gradient the closer something is the more 7 8 distinctly textured it is and the farther away something is the smaller and ner they are a Another trick used by artists Motion Parallax discrepancy in motion of near and far objects Accommodation quotmuscular cuequot for distance and happens inside the eye iii Binocular Cues 1 2 Convergence refers to the rotation of the two eyes in the sockets to focus on a single object a The closer the object the greater the convergence Binocular Disparity because the eyes are a few inches apart they don39t see exactly the same image a If the two images are different the object is very close d Perceptual usions 1 usion perception that does not correspond to reality ii The Hermann Grid 1 3 Grid of black boxes that have the illusion of gray diamonds in the corner of the boxes from the corner of the eye One explanation is attributed to responses of neurons in primary visual cortex that respond best to bars of light of a speci c orientation a quotsimple cellsquot David Hubel and Torsten Wiesel b quotcomplex cellsquot respond to orientation and movement c quotendstopped cellsquot respond best to corners curvature or sudden edges Feature Detectors simple complex and endstopped cells that respond to speci c features of a stimulus iii Miiller Lyerlllusion 1 2 3 Distortion happens when the viewer tries to determine if two lines are exactly the same length Explanation is that most people live in a world with a lot of buildings Marshall Segall and colleagues found that the people in Western cultures quotcarpentered worldquot are far more susceptible to iusion than nonWestern cultures quotuncarpentered worldquot iv The Moon usion 1 The moon on the horizon appears to be much larger than the moon in the sky 2 Apparent Distance Hypothesis moon in the sky has no cues while the moon in horizon appear behind objects making the moon appear farther away and then people quotmagnifyquot the moon in their minds v Illusions of Motion 1 Autokinetic Effect small stationary light in a darkened room will appear to move because there are no surrounding cues to indicate that it is not moving 2 Stroboscopic Motion rapid series of still pictures will seem to be in motion 3 Phi Phenomenon lights turned on in sequence appear to move 4 Eye movements are primary factor in the illusions of moving paintings vi Other Factors that In uence Perception 1 Perceptual Set or Perceptual Expectancy people39s tendency to perceive things a certain way because of previous experience or expectations in uence them 2 TopDown Processing use of preexisting knowledge to organize individual features into a uni ed whole 3 BottomUp Processing analysis of smaller features and building up to a complete perception no expectancy 4 People of different cultures perceive objects differently because of the different expectancy Class Notes Sensann Outside stimuli gt Sensory receptors activated gt neural activity All of that is transduction Difference Threshold Just Noticeable Difference Weber39s Law 50 Absolute Threshold noticing something is there or not Subliminal Perception subliminal below the level of conscious awareness Selective Attention brain shifts out what39s important or not Hab ua on brain ignores certain things that are constant in the environment Sensory Adaptation senses are not ring as much Light Waves Short xray and Long microwaves Visible Color Spectrum Red Orange Yellow Green Blue Violet ultraviolet ultra short The Eye lightgtcorneagtpupilirisgtlensgtretina rods and cones rodsgtblackwhite and peripheral vision conesgt color Color Vision Trichromatic Theory red green and blue cones Color De cient Vision AfterImage Effect Opponent Process Theory red and green blue and yellow Most people who have color blindness are male it39s more common in males than females Depth Perception Monocular Cues one eye is used Linear Perspective Relative Size Binocular Cues Convergence eyeballs rotating in their socket Taste Tonguegttaste buds papillae contain taste buds Five Basic Tastes salty sour bitter sweet umami All parts of the tongue detect all tastes Flavor gestationolfaction avor Perception BottomUp Processing TopDown Processing Perceptual Set tendency to perceive something because of earlier expectations context matters Contrast Effect comparing something by something you just watched
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