sensation and perception
DESCRIPTION
Sensation and Perception. Chapter 5. Threshold. Detecting vs. not detecting Can you hear it, taste it, see it or not? Ex. Grade school hearing test. Absolute threshold. Smallest amount of energy that will produce a sensation Ex. Eye chart determines vision. Difference threshold. - PowerPoint PPT PresentationTRANSCRIPT
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Sensation and Perception
Chapter 5
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Threshold
Detecting vs. not detectingCan you hear it, taste it, see it or not?Ex. Grade school hearing test
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Absolute thresholdSmallest amount of energy that will produce a sensationEx. Eye chart determines vision
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Difference threshold
Smallest change in a stimulus that produces a change
Just noticeably differentEx. 3 lb package in empty
vs. full backpackEx. Darkroom, turn on
light, appears bright
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Weber’s law
Larger or stronger a stimulus, larger the change required for observer to notice
Ex. Yell in empty stadium vs. packer game
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Sensory adaptation
Adapt to constant level of stimuliGet used to new level, respond only to change
Ex. Eyes in a movie theaterWithout adaptation, senses would be bombarded
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Senses
VisionHearingSmellTasteTouchTemperaturePainVestibularkinesthesis
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Kinesthesis
Movement and body positionWithout, movements would
be jerky1st affected by alcoholEx. Touch nose, heel toe
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Vestibular
Motion and balanceUtricle – detects linear motionSemicircular canal – rotary regulated by inner earRollercoaster fun or sickeningOverstimulation causes dizzinesslocated in ear, but linked to vision
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Vestibular nystagmus
Eyes go through a rotary spasm after spinning2nd sense affected by alcoholHorizontal gaze nystagmusVertical gaze nystagmusvideo
http://www.opt.uab.edu/emweb/Nystagmus.htm
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Motion sickness
Disagreement between vision and vestibular sense
Plane – vestibular feels speed, but eyes see nothing
Car – vestibular feels speed, but eyes see different
Boat – unpredictable rates
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Receptors of Skin
PainColdHeatTouch
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TouchReceptor – mechanical sensors send electric signals to the somatosensory cortex
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Touch ContinueSkin – largest organ containing sensors
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Layers of Skin
Epidermis – dead skin, no receptors
Dermis – contain variety of receptors including hair receptors
Fatty layer – pacinian corpusoleHighly sensitive to touch
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Hair receptors
Nerve endings wrapped around the base of each hair follicleAdaptation – when hair remains bentFree nerve endings – give info. about temperature and pain
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Pain
Caused byTissue damageAttentional stateDoing something else, don’t noticeEmotional stateWhen afraid, hurts moreReceptor – send nerve impulses to the somatosensory and limbic area of the brainEndorphins – natural painkiller
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Nerve ending in finger send info along spinal cordThe neurons travel up the spinal cord then form synapses with neurons in the thalamus (magenta circle)The thalamus organizes info and sends to sensory cortex (blue)
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Interprets the information as pain Sends info to motor cortex (orange)Motor cortex (orange) sends info. back to the thalamus (green pathway)Thalamus organizes incoming info. and sends signals down the spinal cordReact to the pain (e.g., shaking the finger or screaming "ouch!").
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Pain contined
Pain tolerance – ability to handle painReferred pain – pain in an area away from the sourceEx. Headache may stem from backpain
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Temperature
Stimulus – change in temperature on skinReceptor – skin and hair folliclesThermoadaptationShort-term – bathtubLong-term – go to Florida in winter
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Taste
Stimulus – chemicals of the substance mixing with salivaReceptors – taste budsSweetSaltySourBitterUmami – meaty-cheese tasteParmasan cheese, fish, meat
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Taste buds
Couple of drops of blue food coloring
http://biology.about.com/library/organs/blpathodigest2.htm?terms=digestive+system+activity
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Taste buds
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Taste buds
Amount inherited – 500-10,000Sends messages to the parietal lobe
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Other factors for Taste
SmellTemperatureTextureAppearanceColor
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Taste Continued
If one changes, all change in opposite directionEx. Drink orange juice after brushing teethTaste lossSmokingAge – lose 30% by age 20AdaptationKeep adding salt to fries
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Smell
Receptor – olfacotry epithelium
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Smell and memory
Transduction -Transforms chemical reaction into a nerve impulseNerves from the olfactory bulb make connections with the limbic systemThe limbic system contains the hypothalamus, the hippocampus, and the amygdalaResponsible for our emotions and in the formation of memories.
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Loss of smell
Virus destroys receptorsDamage to the neurons
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Functions of smell
Potential dangerFire, gas, spoiled foodMemoryChoosing a matePheromones
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Adaptation of smell
Short-termLeave room, come back and it smellsLong-termSignificant odors in your lifePeople with B.O. can’t smell themselves
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Auditory anatomy
Outer earPinna – cartilage covered with skin on both sides of your head “ears”External auditory canalNothing smaller than an elbow should enterContains wax and hair to keep dirt out
http://www.brainconnection.com/topics/?main=anat/auditory-anat
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Middle ear
Ear drum – vibrates messages to the fluid of the cochlea
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Middle ear
OssiclesMalleus (hammer)Inca (anvil)Stapes (stirup)
Ability to freezeEustachian tube – Equalizes pressure
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Inner ear (size of pea)
Cochlea – filled with fluid and hair cellsPick up vibrations from oval windowOrgans of corti – stiff membrane that moves against the hair cells to produce soundEars ringing – permanent hearing lossSemicircular canal – controls balance
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After 120 decibels of noise – equivalent of rock concert
Healthy Damaged
http://concise.britannica.com/ebc/art-529
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Perception
interpretation of what we take in through our senses
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Perceptual Organization
Similarity Proximity Continuity Closure
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Proximity
Objects that are close together appear to go together
Back
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Continuity
Lines are seen as following the smoothest path
Back
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Closure
We tend to ignore gaps and fill in the missing lines
Back
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Figure-Ground
Puts the visual scene into a figure that we look at and a ground which is everything else and forms the background
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Constancy
SizeShapeBrightnessColor
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Size Constancy
Ability to see objects further away as same size
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Shape Constancy
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Color constancy
The ability to see color regardless of changing conditions.
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Brightness Constancy
ability to see objects as having the same brightness even though light may change their immediate sensory properties
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Depth Perception
Monocular cues – need only one eyeBinocular cues – need 2 eyes
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Monocular cues
InterpositionLinear perspectiveElevationTexture gradientMotion parallax
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Interposition
One object appears to be blocking another
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Linear Perspective
Visual field appears to come to a point
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Texture gradient
Objects closer have more detail than objects further away
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Motion Parallax
Objects close to us seem to move faster than objects further awayEx. Fingers vs. boardEx. Plane vs. car
http://psych.hanover.edu/Krantz/MotionParallax/MotionParallax.html
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Binocular Cues
Retinal DisparityImages on the retina are in different places on the eyeClose one eye and pencilConvergence as objects get farther from our face they convergePencil move toward face
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Illusions
Phenomenon which what you see is not actually what is presentMoon illusionHorizontal-vertical illusionMueller-lyerPonzoPaggendorffHering
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Moon illusion
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Mueller-lyer illusion
Due to closure
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Ponzo
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Poggendorff
Larger the angle, more illusion
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Herings illusion
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Afterimage
Color theory – black and white cones become overstimulated and causes afterimage
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After image
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After image
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Illusions
http://home.earthlink.net/~toddwolly/vision/fun.html