ch 4 sensation & perception sensation: your window to the world perception: interpreting what...
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Ch 4 Sensation & Perception
Sensation: your window to the world
Perception: interpreting what comes in your window.
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Sensation & Perception
SensationThe stimulation of sensory receptors
(senses) and the transmission of sensory information to the brain
PerceptionPsychological process of how we interpret
sensory stimulation
3“The Forest Has Eyes,” Bev Doolittle
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Absolute Threshold: the weakest amount of stimulus that can be detected
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Difference Threshold
Difference Threshold: Minimum amount of difference that can be detected between two stimuli, also called just noticeable
difference (JND).
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Signal Detection Theory (SDT)
A method of distinguishing sensory stimuli
Carol L
ee/ Tony Stone Im
ages
The following effect Signal detection:
SettingPhysical state
Mood Attitudes
Sensory Adaptation
• Decreased responsiveness to stimuli due to constant stimulation.
Do you feel your underwear all day?
Energy v. Chemical senses
Energy Senses Chemical Senses
Vision• Our most
dominating sense.• Visual Capture
– Video
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VisibleSpectrum
Light EnergyB
oth
Pho
tos:
Tho
mas
Eis
ner
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The Eye
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Parts of the eye
1. Cornea: Transparent tissue where light enters the eye.
2. Iris: Muscle that expands and contracts to change the size of the opening (pupil) for light.
3. Lens: Focuses the light rays on the retina.
4. Retina: Contains sensory receptors that process visual information and sends it to the brain.
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Retina
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Visual Information Processing
Optic nerves connect to the thalamus in the middle of the brain, and the thalamus
connects to the visual cortex.
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Optic Nerve, Blind Spot & Fovea
http://www.bergen.org
Optic nerve: Carries neural impulses from the eye to the brain. Blind Spot: Point where the optic nerve leaves the eye because there are no receptor cells located there. This creates a blind spot. Fovea: Central point in the retina around which the eye’s cones cluster.
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Test your Blind Spot
Use your textbook. Close your left eye, and fixate your right eye on the black dot. Move the page towards your eye and away from
your eye. At some point the car on the right will disappear due to a blind spot.
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Photoreceptors
E.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969
How we see color in the eye
• Rods (receptors)– Allow us to see in
black in white
• Cones (receptors)– Allow us to see in
color
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Visual Acuity
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The Lens
Nearsightedness: A condition in which nearby objects are seen more clearly
than distant objects.
Farsightedness: A condition in which faraway objects are seen more clearly than near objects.
Vision : In the Brain
• Feature Detectors
We have specific cells that see the lines, motion, curves and other features of this turkey. These cells are called feature detectors.
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Parallel Processing
Processing of several aspects of the stimulus simultaneously is called parallel processing. The
brain divides a visual scene into subdivisions such as color, depth, form and movement etc.
Color Vision
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Color Blindness
Ishihara Test
Genetic disorder in which people are blind to green or red colors.
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Gaze at the middle of the flag for about 30Seconds. When it disappears, stare at the dot and report
whether or not you see Britain's flag.
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Hearing
Our auditory sense
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Frequency (Pitch)
Frequency (pitch): The dimension of
frequency determined by the wavelength
of sound.
Wavelength: The distance from
the peak of one wave to the peak
of the next.
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Intensity (Loudness)
Intensity (Loudness):
Amount of energy in a wave,
determined by the amplitude, relates to the perceived
loudness.
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Quality (Timbre)
Quality (Timbre): Characteristics of sound from a zither and a guitar allows the ear to
distinguish between the two.
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Zither
Guitar
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Loudness of Sound
70dB
120dB
Richard K
aylin/ Stone/ Getty Im
ages
The Ear
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The Ear
Dr. Fred H
ossler/ Visuals U
nlimited
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The Ear
Outer Ear: Pinna. Collects sounds.
Middle Ear: Chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window.
Inner Ear: Innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs.
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Localization of Sounds
Because we have two ears, sounds that reach one ear faster than the other ear
cause us to localize the sound.
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Hearing Loss
Conduction Hearing Loss: Hearing loss caused by damage to the middle ear
Sensorineural Hearing Loss: Hearing loss caused by damage to the cochlea’s and inner ear. Also called nerve deafness.
DeafnessConduction Deafness
• Something goes wrong with the sound and the vibration on the way to the cochlea.
• You can replace the bones or get a hearing aid to help.
Nerve (sensorineural) Deafness
• The hair cells in the cochlea get damaged.
• Loud noises can cause this type of deafness.
• NO WAY to replace the hairs.
• Cochlea implant is possible.
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Deaf Culture
Cochlear implants are electronic devices that enable the brain to hear sounds.
Cochlear ImplantDeaf Musician
EG
Images/ J.S. W
ilson ©
Wolfgang G
stottner. (2004) Am
erican Scientist, V
ol. 92, Num
ber 5. (p. 437)
45
Smell
Like taste, smell is a chemical sense. Odorants enter the nasal cavity to stimulate
5 million receptors to sense smell. Unlike taste, there are many different forms of
smell.
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Smell and Memories
The brain region for smell (in red) is
closely connected with the brain
regions involved with memory (limbic system). That is why strong memories are
made through the sense of smell.
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Taste
Traditionally, taste sensations consisted of sweet, salty, sour, and bitter tastes.
Recently, receptors for a fifth taste have been discovered called “Umami”.
Sweet Sour Salty Bitter Umami(Savory)
Taste
• We have bumps on our tongue called papillae.
• Taste buds are located on the papillae (they are actually all over the mouth).
• Sweet, salty, sour and bitter.
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Sensory Interaction
When one sense affects another sense, sensory interaction takes place. So, the
taste of strawberry interacts with its smell and its texture on the tongue to produce
flavor.
Taste Lab
The Skin Sense: Touch
• Receptors located in our skin.• Pain, Pressure, Warmth &
Cold
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Pain
Pain tells the body that something has gone wrong. Usually pain results from damage to the skin and other tissues. A rare disease exists in
which the afflicted person feels no pain.
Ashley Blocker (right) feels neither painnor extreme hot or cold.
AP Photo/ Stephen M
orton
52
Body Position and Movement
The sense of our body parts’ position and movement is called kinesthesis. The
vestibular sense monitors the head (and body’s) position.
http
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Whirling Dervishes Wire Walk
Bob D
aemm
rich/ The Im
age Works
Kinesthetic Sense
• Tells us where our body parts are.
• Receptors located in our muscles and joints.
Without the kinesthetic sense you could touch the button to make copies of your buttocks.
Vestibular Sense
• Tells us where our body is oriented in space.
• Our sense of balance.
• Located in our semicircular canals in our ears.
• LAB
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