Upload
alvin-riley
View
20
Download
1
Tags:
Embed Size (px)
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 Presentation
Citation preview
Sensation and Perception
Chapter 5
Threshold
Detecting vs. not detectingCan you hear it, taste it, see it or not?Ex. Grade school hearing test
Absolute thresholdSmallest amount of energy that will produce a sensationEx. Eye chart determines vision
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
Weber’s law
Larger or stronger a stimulus, larger the change required for observer to notice
Ex. Yell in empty stadium vs. packer game
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
Senses
VisionHearingSmellTasteTouchTemperaturePainVestibularkinesthesis
Kinesthesis
Movement and body positionWithout, movements would
be jerky1st affected by alcoholEx. Touch nose, heel toe
Vestibular
Motion and balanceUtricle – detects linear motionSemicircular canal – rotary regulated by inner earRollercoaster fun or sickeningOverstimulation causes dizzinesslocated in ear, but linked to vision
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
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
Receptors of Skin
PainColdHeatTouch
TouchReceptor – mechanical sensors send electric signals to the somatosensory cortex
Touch ContinueSkin – largest organ containing sensors
Layers of Skin
Epidermis – dead skin, no receptors
Dermis – contain variety of receptors including hair receptors
Fatty layer – pacinian corpusoleHighly sensitive to touch
Hair receptors
Nerve endings wrapped around the base of each hair follicleAdaptation – when hair remains bentFree nerve endings – give info. about temperature and pain
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
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)
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!").
Pain contined
Pain tolerance – ability to handle painReferred pain – pain in an area away from the sourceEx. Headache may stem from backpain
Temperature
Stimulus – change in temperature on skinReceptor – skin and hair folliclesThermoadaptationShort-term – bathtubLong-term – go to Florida in winter
Taste
Stimulus – chemicals of the substance mixing with salivaReceptors – taste budsSweetSaltySourBitterUmami – meaty-cheese tasteParmasan cheese, fish, meat
Taste buds
Couple of drops of blue food coloring
http://biology.about.com/library/organs/blpathodigest2.htm?terms=digestive+system+activity
Taste buds
Taste buds
Amount inherited – 500-10,000Sends messages to the parietal lobe
Other factors for Taste
SmellTemperatureTextureAppearanceColor
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
Smell
Receptor – olfacotry epithelium
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.
Loss of smell
Virus destroys receptorsDamage to the neurons
Functions of smell
Potential dangerFire, gas, spoiled foodMemoryChoosing a matePheromones
Adaptation of smell
Short-termLeave room, come back and it smellsLong-termSignificant odors in your lifePeople with B.O. can’t smell themselves
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
Middle ear
Ear drum – vibrates messages to the fluid of the cochlea
Middle ear
OssiclesMalleus (hammer)Inca (anvil)Stapes (stirup)
Ability to freezeEustachian tube – Equalizes pressure
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
After 120 decibels of noise – equivalent of rock concert
Healthy Damaged
http://concise.britannica.com/ebc/art-529
Perception
interpretation of what we take in through our senses
Perceptual Organization
Similarity Proximity Continuity Closure
Proximity
Objects that are close together appear to go together
Back
Continuity
Lines are seen as following the smoothest path
Back
Closure
We tend to ignore gaps and fill in the missing lines
Back
Figure-Ground
Puts the visual scene into a figure that we look at and a ground which is everything else and forms the background
Constancy
SizeShapeBrightnessColor
Size Constancy
Ability to see objects further away as same size
Shape Constancy
Color constancy
The ability to see color regardless of changing conditions.
Brightness Constancy
ability to see objects as having the same brightness even though light may change their immediate sensory properties
Depth Perception
Monocular cues – need only one eyeBinocular cues – need 2 eyes
Monocular cues
InterpositionLinear perspectiveElevationTexture gradientMotion parallax
Interposition
One object appears to be blocking another
Linear Perspective
Visual field appears to come to a point
Texture gradient
Objects closer have more detail than objects further away
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
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
Illusions
Phenomenon which what you see is not actually what is presentMoon illusionHorizontal-vertical illusionMueller-lyerPonzoPaggendorffHering
Moon illusion
Mueller-lyer illusion
Due to closure
Ponzo
Poggendorff
Larger the angle, more illusion
Herings illusion
Afterimage
Color theory – black and white cones become overstimulated and causes afterimage
After image
After image
Illusions
http://home.earthlink.net/~toddwolly/vision/fun.html