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Transcript of 1 Sensation & Perception. Fraser’s Spiral 2 3 What Is Sensation? It occurs when a stimulus...
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Sensation & PerceptionSensation & Perception
Fraser’s SpiralFraser’s Spiral
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What Is Sensation?What Is Sensation?
It occurs when a It occurs when a stimulus activates a stimulus activates a sensory receptorsensory receptor
A stimulus is measured A stimulus is measured by the following: size, by the following: size, intensity, duration, intensity, duration, wavelengthwavelength
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What Is Perception?What Is Perception?
The organization of sensory information The organization of sensory information into meaningful experiencesinto meaningful experiences
Psychophysics: the study of how Psychophysics: the study of how physical stimuli are translated into physical stimuli are translated into psychological experiencepsychological experience
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Gustav FechnerGustav Fechner
Created experiments Created experiments that measured sensory that measured sensory data data
Laid the basis for Laid the basis for psychophysicspsychophysics
Black roomBlack roomgardengarden Systematic relationship Systematic relationship
between physical & between physical & mental experiencesmental experiences
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What Is Meant by a What Is Meant by a Threshold?Threshold?
Stimulus—any detectable Stimulus—any detectable input from the env’tinput from the env’t
Threshhold—dividing point Threshhold—dividing point between energy levels that do between energy levels that do & don’t have a detectable & don’t have a detectable effecteffect
Absolute threshold: Absolute threshold: the smallest amount the smallest amount of a stimulus that a of a stimulus that a person can reliably person can reliably detectdetect
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Absolute Thresholds Absolute Thresholds Vision: a flame from a Vision: a flame from a
single candle 30 miles single candle 30 miles awayaway
Hearing: ticking of a Hearing: ticking of a watch 20 feet awaywatch 20 feet away
Taste: one teaspoon of Taste: one teaspoon of sugar in two gallons of sugar in two gallons of waterwater
Smell: one drop of Smell: one drop of perfume in a small perfume in a small househouse
Touch: the wing of a bee Touch: the wing of a bee brushing your cheekbrushing your cheek
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Difference ThresholdDifference Threshold
The minimal difference in the magnitude of The minimal difference in the magnitude of energy needed for people to distinguish energy needed for people to distinguish between two stimulibetween two stimuli
AKA Just Noticeable DifferenceAKA Just Noticeable Difference Weber’s law and expertsWeber’s law and experts
The size of a JND is proportionate to the size of the The size of a JND is proportionate to the size of the initial stimulusinitial stimulus
Full backpack—won’t notice adding a spiralFull backpack—won’t notice adding a spiral Empty backpack—will notice itEmpty backpack—will notice it Sample Video
Fechner’s LawFechner’s Law
The magnitude of a sensory experience The magnitude of a sensory experience is proportional to the magnitude of JNDs is proportional to the magnitude of JNDs that the stimulus causing the experience that the stimulus causing the experience is above absolute thresholdis above absolute threshold
1 lamp1 lamp2 lamps2 lamps3 lamps3 lamps
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Signal-Detection TheorySignal-Detection Theory
The study of The study of people’s people’s tendencies to tendencies to make correct make correct judgments in judgments in detecting the detecting the presence of presence of stimulistimuli
Signal Present
Signal Absent
Says YES “present”
HIT FALSE ALARM
Says NO“absent”
MISS Correct Rejection
Other examples of signal Other examples of signal detection theory:detection theory:
Listening for pizza guyListening for pizza guy Searching for cancer cellsSearching for cancer cells Home alone soundsHome alone sounds Military patrolsMilitary patrols
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The Stroop EffectThe Stroop Effect
A B
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Processing StimuliProcessing Stimuli Preattentive process—extracting information automatically Preattentive process—extracting information automatically
& simultaneously when presented with stimuli (makes it & simultaneously when presented with stimuli (makes it hard to read the words with competing colors)hard to read the words with competing colors)
Attentive process—considers only one part of the stimuli at Attentive process—considers only one part of the stimuli at a timea time
Selective attentionSelective attention Awareness Test 1 1 Awareness Test 2
Cocktail Party Phenomenon--being able to focus one's Cocktail Party Phenomenon--being able to focus one's auditory attention on a particular stimulus while filtering out auditory attention on a particular stimulus while filtering out a range of other stimuli, much the same way that a a range of other stimuli, much the same way that a partygoer can focus on a single conversation in a noisy partygoer can focus on a single conversation in a noisy roomroom
Subliminal PerceptionSubliminal Perception Registration of sensory input without Registration of sensory input without
conscious awarenessconscious awareness ““Eat popcorn” (1957)Eat popcorn” (1957) Defenseless!?!Defenseless!?! Evidence that perception without awareness Evidence that perception without awareness
can take placecan take place Effects are VERY minimalEffects are VERY minimal Stairway to Heaven—Led Zeppelin Another One Bites the Dust—Queen http://jeffmilner.com/backmasking/index.html
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Sensory AdaptationSensory Adaptation
Senses are most Senses are most responsive to responsive to increases and increases and decreases rather than decreases rather than ongoing unchanging ongoing unchanging stimulationstimulation
Our senses have the Our senses have the ability to adaptability to adapt
HabituationHabituation (Stinky trash; itchy (Stinky trash; itchy
sweater)sweater)
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Vision Vision Cornea: “window” at Cornea: “window” at
the front of the eye; the front of the eye; light enters here and light enters here and the image is flippedthe image is flipped
Pupil: the opening in Pupil: the opening in the iris that regulates the iris that regulates the amount of lightthe amount of light
Lens: the flexible and Lens: the flexible and transparent part of the transparent part of the eye that changes its eye that changes its shape to focus light in shape to focus light in the retinathe retina
Retina: the innermost Retina: the innermost coating of the back of coating of the back of the eyethe eye
Video clip: how vision works
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Pupil
Iris
Lens
Optic Nerve
retina
Cornea
vitreous
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The Human Eye: Rods The Human Eye: Rods and Conesand Cones
Cones require more Cones require more light than rods and light than rods and work best in daylightwork best in daylight Color visionColor vision
Rods are more Rods are more important for night important for night visionvision Black and white visionBlack and white vision
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The Fovea and the Blind The Fovea and the Blind SpotSpot
Fovea: the part of the Fovea: the part of the retina that retina that corresponds to the corresponds to the center of our gazecenter of our gaze
Blind spot: the part of Blind spot: the part of the retina where the the retina where the optic nerve leaves optic nerve leaves the eye (Optic Disc)the eye (Optic Disc)
Nearsighted vs. Nearsighted vs. farsightedfarsighted
Peripheral Vision clip
Visual PathwayVisual Pathway
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On the RETINA:
Rods & Cones Bipolar Cells Ganglion Cells (Transduction) Out the eye through the Optic Nerve Optic Chiasm Thalamus Visual Cortex in Occipital Lobe
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Visual Pathways to the Visual Pathways to the BrainBrain
Input from the right half Input from the right half of the visual field strikes of the visual field strikes the left side of each the left side of each retina and is transmitted retina and is transmitted to the left hemisphere to the left hemisphere (shown in red)(shown in red)
Input from the left half of Input from the left half of the visual field strikes the visual field strikes the right side of each the right side of each retina & is transmitted to retina & is transmitted to the right hemisphere the right hemisphere (shown in green)(shown in green)
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David HubelDavid Hubel
Won the Nobel Prize for his work on Won the Nobel Prize for his work on how humans transform sensory how humans transform sensory informationinformation
Planted electrodes in a cat’s visual Planted electrodes in a cat’s visual cortexcortex
Feature detectionFeature detection Their experiment involved implanting Their experiment involved implanting
electrodes into a cat's visual cortex. They electrodes into a cat's visual cortex. They then flashed the different visual stimuli on a then flashed the different visual stimuli on a screen within the cat’s field of vision and screen within the cat’s field of vision and observed which cells fired in response to the observed which cells fired in response to the different stimuli. They called these cells different stimuli. They called these cells “feature detectors.”“feature detectors.”
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LightLight
The visible portion of the electromagnetic The visible portion of the electromagnetic spectrumspectrum
The colors we see are different The colors we see are different wavelengths of lightwavelengths of light
We see color when light waves hit We see color when light waves hit objects and bounce back to us at varying objects and bounce back to us at varying speedsspeeds
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WavelengthWavelength determines color determines color Longer = red / shorter = violetLonger = red / shorter = violet
AmplitudeAmplitude determines brightness determines brightness PurityPurity determines saturation determines saturation
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Color DeficiencyColor Deficiency
Occurs when a person’s cones do not Occurs when a person’s cones do not function properlyfunction properly
Different types of color deficiency:Different types of color deficiency:
A. Some see certain colorsA. Some see certain colors
B. Totally color deficientB. Totally color deficient
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Color VisionColor Vision
Color receptors in the Color receptors in the retina transmit retina transmit messages to the brain messages to the brain when visible lights when visible lights having different having different wavelengths stimulate wavelengths stimulate themthem
Hermann von HelmholtzHermann von Helmholtz
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Thomas Young’s WorkThomas Young’s Work The three primary colors of light The three primary colors of light
(red, green, blue) combine to (red, green, blue) combine to form whiteform white
Young showed that you could Young showed that you could create any color of light by create any color of light by mixing these component colors mixing these component colors and varying their brightnessand varying their brightness
Trichromatic theory—Trichromatic theory—Said the Said the eye has 3 color receptors eye has 3 color receptors (cones). 3 cones have differing (cones). 3 cones have differing sensitivities to different sensitivities to different wavelengths of light—allowing wavelengths of light—allowing us to see different colors.us to see different colors.
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Opponent Process Opponent Process Theory: AfterimagesTheory: Afterimages
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Complementary Complementary AfterimageAfterimage
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AfterimageAfterimage
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Counter-Rotating SpiralsCounter-Rotating Spirals
Fatiguing your eyes:Fatiguing your eyes:
Counter-Rotating Spirals IllusionCounter-Rotating Spirals Illusion
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HearingHearing
Depends on sound Depends on sound waves or vibrationswaves or vibrations
Sound waves pass Sound waves pass through various bones in through various bones in the inner earthe inner ear
Thin, hair-like cells move Thin, hair-like cells move back and forthback and forth
Sound LocalizationSound Localization
Cupping earsCupping ears Sound localizationSound localization
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LoudnessLoudness
Decibels: measures of Decibels: measures of loudnessloudness
Each 10-decibel Each 10-decibel increase makes a sound increase makes a sound 10 times louder10 times louder
Sound travels through Sound travels through the air at 1130 feet per the air at 1130 feet per secondsecond
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PitchPitch
The highness or lowness The highness or lowness of a sound that of a sound that corresponds to the corresponds to the frequency of a sound frequency of a sound wavewave
The ear senses sound The ear senses sound waves that vary from 20 waves that vary from 20 to 20,000 cycles per to 20,000 cycles per secondsecond
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The Path of SoundThe Path of Sound
Sound waves are Sound waves are funneled by the outer ear funneled by the outer ear to the eardrum, causing it to the eardrum, causing it to vibrateto vibrate
Ossicles and oval Ossicles and oval window, cochleawindow, cochlea
IN THE COCHLEA:IN THE COCHLEA: Basilar membranes Basilar membranes
(Transduction), Organ of (Transduction), Organ of Corti, hair-cell receptorsCorti, hair-cell receptors
Hearing pathway animationHearing pathway animation
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Sound waves vibrate bones of the middle ear
Stirrup hits against the oval window of cochleaSets the fluid inside in motion
Hair cells are stimulated with the movement of the basilar membrane
Physical stimulation converted into neural impulses
Sent through the thalamus to the auditory cortex (temporal lobes)
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Hearing LossHearing Loss
30 million Americans 30 million Americans have hearing problemshave hearing problems
2 million are deaf2 million are deaf Causes: birth defects, Causes: birth defects,
disease, advanced age, disease, advanced age, injury, overexposureinjury, overexposure
Conduction DeafnessConduction Deafness Caused by the failure of Caused by the failure of
the three tiny bones the three tiny bones inside the middle ear to inside the middle ear to pass along sound waves pass along sound waves to the inner ear or the to the inner ear or the failure of the eardrum to failure of the eardrum to vibrate in response to vibrate in response to sound waves sound waves
Possible cause is a build-Possible cause is a build-up of fluidup of fluid
Hearing aids Hearing aids Normal hearing may Normal hearing may
return.return.
Sensory-Neural DeafnessSensory-Neural Deafness
Damage to the inner Damage to the inner ear. Most often caused ear. Most often caused by loss of hair cells by loss of hair cells that will not that will not regenerate”regenerate”
Damage to the Damage to the auditory nerve.auditory nerve.
Cochlear implants can Cochlear implants can help patients with this help patients with this form of deafness.form of deafness.
Video: First time hearing with Video: First time hearing with cochlear implantcochlear implant Video: Boy gets auditory nerve
implant
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Stimulation DeafnessStimulation Deafness
Exposure to very loud Exposure to very loud soundssounds
Prolonged exposure Prolonged exposure to 85 dB can cause to 85 dB can cause stimulation loss.stimulation loss.
Ringing sound can Ringing sound can mean hair cells have mean hair cells have been damagedbeen damaged
Video: How Old are Your Video: How Old are Your EarsEars
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Smell and TasteSmell and Taste
The chemical sensesThe chemical senses ““gustatory system”—gustatory system”—
sense system for tastesense system for taste ““olfactory system”—olfactory system”—
system for smellsystem for smell Nerve impulses travel Nerve impulses travel
through the olfactory through the olfactory nerve to the olfactory nerve to the olfactory bulb in the brain, causing bulb in the brain, causing sensation of specific sensation of specific odorsodors
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Supertasters vs. nontastersSupertasters vs. nontasters People who have greater People who have greater
taste sensibilities than otherstaste sensibilities than others Supertasters have two to Supertasters have two to
three times more taste buds three times more taste buds than normalthan normal
Gender & ethnic differences Gender & ethnic differences in taste sensitivityin taste sensitivity Asian women most likely to be Asian women most likely to be
“super” “super” White males least likely; White males least likely;
evolutionary perspective—evolutionary perspective—women as gatherers--women as gatherers--supertasterssupertasters
Video: SupertastersVideo: Supertasters
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The Olfactory BulbThe Olfactory Bulb
Located in the front of Located in the front of the brain above the the brain above the nostrilsnostrils
Olfactory cortex is Olfactory cortex is located in the temporal located in the temporal lobelobe
Connections to the Connections to the limbic systemlimbic system
Sensations are created by chemical reactions on your taste buds (gustation)
Taste is heavily influenced by smell – this is called sensory interaction
Taste buds==neural impulse==thalamus==cortex
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TASTE QUALITIESTASTE QUALITIES
(taste is a bunch of B (taste is a bunch of B S’s!)S’s!)
•BBitteritter
•SSourour
•SSaltyalty
•SSweetweet
FLAVOR DEPENDS ON…•Temperature
•Odor
•Texture
•Taste(I T.O.T.T. you about flavor)
http://www.npr.org/templates/story/story.php?storyId=1813416Study: Tastes Form in Infancy
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SkinSkin The skin is the largest The skin is the largest
sensory organsensory organ Touch, pressure, warmth, Touch, pressure, warmth,
cold, pain, fine touchcold, pain, fine touch Example: “wetness” is from Example: “wetness” is from
touch and coldtouch and cold 1.5 million receptors for 1.5 million receptors for
touch and pressure, touch and pressure, somatosensory cortexsomatosensory cortex
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Pathways for Pain Pathways for Pain SignalsSignals
Receptors send pain Receptors send pain signals to the brain along signals to the brain along two pathwaystwo pathways
Gate control mechanism: Gate control mechanism: incoming pain sensations incoming pain sensations must pass through a gate must pass through a gate in the spinal cord that can in the spinal cord that can be open or closed be open or closed (diverted attention can (diverted attention can deflect pain)deflect pain)
Endorphins released Endorphins released through acupuncturethrough acupuncture
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KINESTHESISKINESTHESIS – The – The sense that informs us sense that informs us about the positions and about the positions and motion of parts of our motion of parts of our bodiesbodies
VESTIBULAR SENSEVESTIBULAR SENSE – – The sense of equilibrium The sense of equilibrium (body balance) that (body balance) that informs us about our informs us about our bodies’ positions relative bodies’ positions relative to gravity (semicircular to gravity (semicircular canals) canals) (Your head’s position)(Your head’s position)
Other sensesOther senses
SynesthesiaSynesthesia
http://www.youtube.com/watch?http://www.youtube.com/watch?v=rkRbebvoYqIv=rkRbebvoYqI
Write notes about synethesia…Write notes about synethesia…
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Kangaroo CareKangaroo Care(Gwen 3 weeks old)(Gwen 3 weeks old)
6363Australian Preemie Saved with Kangaroo Care
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PerceptionPerception
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A Changing PictureA Changing Picture
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Defining PerceptionDefining Perception
An active processAn active process The brain pieces The brain pieces
together bits of sensory together bits of sensory information in order to information in order to form orderly impressions form orderly impressions or picturesor pictures
GestaltGestalt 1) Figure-ground1) Figure-ground
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Gestalt Principle #1: Gestalt Principle #1: ProximityProximity
““Meaningful wholes Meaningful wholes seem to precede seem to precede parts and properties, parts and properties, as the Gestalt as the Gestalt psychologists psychologists emphasized years emphasized years ago.” –Anne ago.” –Anne TriesmanTriesman
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Gestalt Principle # 2: Gestalt Principle # 2: SimilaritySimilarity
When similar and When similar and dissimilar objects are dissimilar objects are mingled together, we mingled together, we see the similar see the similar objects as groupsobjects as groups
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Gestalt Principle # 3: Gestalt Principle # 3: ContinuityContinuity
We tend to see We tend to see continuous patterns, continuous patterns, not disrupted onesnot disrupted ones
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Gestalt Principle # 4: Gestalt Principle # 4: SimplicitySimplicity
We perceive the We perceive the simplest shapes simplest shapes possiblepossible
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Gestalt Principle # 5: Gestalt Principle # 5: ClosureClosure
Occurs when people Occurs when people see a familiar pattern see a familiar pattern or shape with some or shape with some missing partsmissing parts
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Perceptual Perceptual InferenceInference
Perceptions are not always based on Perceptions are not always based on sensory informationsensory information
Perceptual Perceptual inferenceinference: occurs when we fill : occurs when we fill in the gaps in what our senses tell usin the gaps in what our senses tell us
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Subliminal PerceptionSubliminal Perception
The Hidden PersuadersThe Hidden Persuaders, Vance Packard, Vance Packard SubSub (below); (below); limenlimen (threshold) (threshold) Subliminal messagesSubliminal messages Congressional and FCC alertsCongressional and FCC alerts
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Subliminal PerceptionSubliminal Perception
The ability to notice The ability to notice stimuli that affect only stimuli that affect only the unconscious mindthe unconscious mind
Controversy and Brian Controversy and Brian Wilson KeyWilson Key
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Subliminal PerceptionSubliminal Perception
The ability to notice The ability to notice stimuli that affect stimuli that affect only the unconscious only the unconscious mindmind
Controversy and Controversy and Brian Wilson KeyBrian Wilson Key
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In the Eye of the In the Eye of the BeholderBeholder
According to Key, According to Key, advertisers routinely advertisers routinely place subliminal place subliminal stimuli in their adsstimuli in their ads
Subliminal self-helpSubliminal self-help
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Two Types Of StimuliTwo Types Of Stimuli
DistalDistal ProximalProximal Developing a Developing a
perceptual perceptual hypothesishypothesis
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Depth PerceptionDepth Perception
The ability to recognize The ability to recognize distance and three-distance and three-dimensional imagesdimensional images
Binocular vs. monocular Binocular vs. monocular cuescues
Retinal disparity and Retinal disparity and convergenceconvergence
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Monocular CuesMonocular Cues
Depth cues about Depth cues about distance are based on distance are based on the image one eye or the the image one eye or the other seesother sees
Six cues: interposition, Six cues: interposition, height in plane, texture height in plane, texture gradient, relative size, gradient, relative size, light and shadow, linear light and shadow, linear perspectiveperspective
Monocular CuesMonocular Cues Linear Perspective—parallel lines Linear Perspective—parallel lines
converging in the distanceconverging in the distance
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Texture Gradient—Closer objects Texture Gradient—Closer objects show more textureshow more texture
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Interposition—nearer objects Interposition—nearer objects mask parts of distant objectsmask parts of distant objects
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Relative Size—Closer objects Relative Size—Closer objects appear to be largerappear to be larger
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Height in plane—The further Height in plane—The further away, the higher the object can away, the higher the object can appear in the frame of viewappear in the frame of view
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Motion Parallax—Closer objects seem to Motion Parallax—Closer objects seem to move faster than more distant objects move faster than more distant objects (like when you are in a car)(like when you are in a car)
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Binocular Cues (using Binocular Cues (using BOTH eyes)BOTH eyes)
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Retinal Disparity: Different images in both Retinal Disparity: Different images in both eyes help with depth perceptioneyes help with depth perception Finger in front of your eyesFinger in front of your eyes
Convergence: Your eyes converge with Convergence: Your eyes converge with closer figurescloser figures Finger in front of your eyesFinger in front of your eyes
Stereograms an exampleStereograms an example
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Optical IllusionsOptical Illusions
Perceptions based on Perceptions based on inappropriate inappropriate assumptions/discrepancassumptions/discrepancy between the y between the appearance of a visual appearance of a visual stimulus and its physical stimulus and its physical realityreality
Muller-Lyer illusionMuller-Lyer illusion
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Another IllusionAnother Illusion Roger Shepard Roger Shepard
(1990)(1990) The Ames The Ames
RoomRoom
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Objects that Objects that can be can be represented in represented in two-two-dimensional dimensional pictures may pictures may not be able to not be able to exist in three-exist in three-dimensional dimensional spacespace
Bottom-up Bottom-up processingprocessing
An Impossible FigureAn Impossible Figure
Perceptual ConstanciesPerceptual Constancies
SizeSize ShapeShape BrightnessBrightness HueHue Location in SpaceLocation in Space
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Shape constancyShape constancy
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Brightness ConstancyBrightness Constancy
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Hue/Color ConstancyHue/Color Constancy
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Perceptual SetPerceptual Set
“Perceptual set” refers to the fact that our perceptions tend to be influenced by our preconceived notions and expectations
Perceptual Set--Perceptual Set--BackmaskingBackmasking
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Two Modes of ProcessingTwo Modes of Processing
Hubel and WieselHubel and Wiesel Bottom-up (see the Bottom-up (see the
parts & then see the parts & then see the whole)whole)
Top-down (We see Top-down (We see someone in the someone in the distance & we fill in distance & we fill in what we don’t see.)what we don’t see.)
Top Down ProcessingTop Down Processing
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Other illusions…Other illusions…
DragonDragon Necker CubeNecker Cube Impossible MotionImpossible Motion DotsDots
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Extrasensory Perception Extrasensory Perception (ESP)(ESP)
The ability to gain information by some The ability to gain information by some means other than the normal sensesmeans other than the normal senses
Paranormal phenomena and Paranormal phenomena and parapsychologyparapsychology
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The “Sixth Sense”The “Sixth Sense”
The major focus includes the following: The major focus includes the following: Telepathy, clairvoyance, precognition, Telepathy, clairvoyance, precognition, and psychokinesisand psychokinesis
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TelepathyTelepathy
Communication of thoughts from one Communication of thoughts from one mind to another that occurs without the mind to another that occurs without the use of our known sensesuse of our known senses
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ClairvoyanceClairvoyance
The ability to perceive objects and events The ability to perceive objects and events without using the senseswithout using the senses
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Precognition and Precognition and PsychokinesisPsychokinesis
Precognition: the ability to foretell the Precognition: the ability to foretell the future future
Psychokinesis: the ability to move objects Psychokinesis: the ability to move objects through mental effort alone through mental effort alone