Sensation and Perception
-
Upload
jamalia-leblanc -
Category
Documents
-
view
20 -
download
0
description
Transcript of Sensation and Perception
![Page 1: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/1.jpg)
Sensation and Perception
![Page 2: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/2.jpg)
Psychophysics
Vision Audition Touch Chemical Senses KinestheticSystem
VestibularSystem
Our Senses Attention
Sensation and Perception
![Page 3: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/3.jpg)
Psychophysics
the study of how physical stimuli are translated into psychological experience
Sensation vs PerceptionOliver Sak’s “Dr. P”
![Page 4: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/4.jpg)
Psychophysics
Sensation the stimulation of sense organs
Perception the selection, organization and interpretation
of sensory input“Dr. P”
visual sensation was intact visual perception was severely impaired “visual agnosia”
![Page 5: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/5.jpg)
Basic Concepts of Psychophysics
stimulus any detectable input from the environment
threshold dividing point between energy levels that do
and do not have a detectable effect absolute threshold
minimum amount of stimulation that an organism can detect
defined as the level where the stimulus intensity is detected 50% of the time
![Page 6: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/6.jpg)
Basic Concepts of Psychophysics
JND (Just Noticeable Difference)smallest difference in amount of stimulation
that a specific sense can detectWeber’s Law
• the size of a JND is in proportion to the size of the initial stimulus
• as stimuli increase in magnitude, the JND becomes larger
Fechner’s Law• constant increments in stimulus intensity produce
smaller and smaller increases in the perceived magnitude of sensation
![Page 7: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/7.jpg)
Subliminal Perception
registration of sensory input without conscious awareness “Eat popcorn” rock music “backward masking” self-help tapes priming
altering participants’ attitude towards target person depending on type of subliminal photos seen
visual priming/semantic priming
![Page 8: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/8.jpg)
Basic Concepts of Psychophysics
Signal Detection Theorydetection of a stimulus involves sensory processes
but also emotional and cognitive processes“noise” from irrelevant stimuli in the environment
Sensory Adaptationgradual decline in sensitivity to prolonged
stimulationautomatic, built-in process designed to keep people
tuned in to changes rather than constants in their sensory input
• Shouldn’t need constant confirmation that your clothes are still on!
![Page 9: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/9.jpg)
W. W. Norton
![Page 10: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/10.jpg)
Psychophysics
Vision Audition Touch Chemical Senses KinestheticSystem
VestibularSystem
Our Senses Attention
Sensation and Perception
![Page 11: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/11.jpg)
Vision: The Stimulus
Light electromagnetic waves amplitude brightness wavelength colour purity “richness” or “saturation”
incoming visual input must be converted into neural impulses
![Page 12: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/12.jpg)
Nature of the stimulus:
-one small band of electromagnetic radiation.
![Page 13: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/13.jpg)
W. W. Norton
![Page 14: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/14.jpg)
Optic Disk: point where the ganglion cell axons converge and exit the retina.
-creates a blind spot in the visual field.
![Page 15: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/15.jpg)
Retina
-contains: Photoreceptor cellsInterneurons.Retinal ganglion cells.
![Page 16: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/16.jpg)
1. Outer Nuclear Layer:
-contains the photoreceptor cells.
}Outer Nuclear Layer
![Page 17: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/17.jpg)
2. Inner Nuclear Layer:
-contains the interneurons:bipolar, amacrine & horizontal cells.
-transmit signals from the photoreceptor cells toganglion cells.
}Outer Nuclear Layer
}Inner Nuclear Layer
![Page 18: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/18.jpg)
3. Ganglion Cell Layer:-contains ganglion cells.
-output cells of the retina.
-axons form the optic nerve.
}Outer Nuclear Layer
}Inner Nuclear Layer
}Ganglion Cell Layer
![Page 19: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/19.jpg)
Photoreceptor CellsTwo types:
RodsCones
![Page 20: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/20.jpg)
Rods:-very sensitive to light.
-used in dim light.
-dense in periphery of retina
![Page 21: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/21.jpg)
Fovea:
-center of the retina.
-densely packed with cones.
![Page 22: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/22.jpg)
Cone vs Rod Vision
Perception of an item and the perception of color are separate.
A volunteer please!
![Page 23: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/23.jpg)
Trichromatic Theory of Color Vision-three types.
-each sensitive to a particular wavelength of light
-red, blue, green
![Page 24: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/24.jpg)
Trichromatic Theory of Color Vision
![Page 25: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/25.jpg)
Opponent Process Theory of Color Vision
Ganglion cells (and neurons) depend on receptors that respond best to pairs of colours.
Yellow onBlue off
Blue onYellow off
Red onGreen off
Green onRed off
![Page 26: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/26.jpg)
Theory of Color Vision
Cones appear to follow trichromatic theory
Lateral Geniculate Nucleus and Visual Cortex appear to follow opponent process theory
so … takes both theories to explain color vision
![Page 27: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/27.jpg)
Colour Blindness
2 - 8% of males..03% of females.
due to a loss or mutation of pigment gene.Red/Green is most common.
![Page 28: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/28.jpg)
First Stage of Visual Processing
![Page 29: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/29.jpg)
Information Processing in the Retina
Info from about 130 million rods and cones converge upon 1 million axons in the optic nerve
bipolar and ganglion cells in the intermediate layers integrate and compress signals from many receptors.
Axons from the ganglion cells form the optic nerve
![Page 30: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/30.jpg)
Information Processing in the Cortex
Feature Detectors (Hubel & Wiesel) neurons respond selectively to very specific
features of more complex stimulisimple cells
respond best to line of correct width, oriented at the correct angle and located in correct position in receptive field
complex cells respond best to specific width and orientation but
any position in receptive field
![Page 31: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/31.jpg)
Information Processing in the Cortex
Parallel processing simultaneously extracting different
kinds of info from same input Parvocellular channel Magnocellular channel
![Page 32: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/32.jpg)
Information Processing in the Cortex
Parallel processing Parvocellular channel
process details about the objects“what” channelhandles perception of color, form and texture__________ lobeprosopagnosia
Magnocellular channelprocesses “where” the ojbects areperception of motion and depth__________ lobe
![Page 33: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/33.jpg)
Review
1. Physical Shapeelongated stubby
2. number 125 million 6.4 million
3. area of retinawhere dominant
Periphery Center/fovea
4. critical to colorvision?
No Yes
5. critical toperipheralvision?
Yes No
6. sensitivity todim light
Strong Weak
Dimension Rods Cones
![Page 34: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/34.jpg)
CENTRAL VISUAL PATHWAYS
Optic nerve: fibres from retina to the optic chiasm.
Optic chiasm: optic nerves from both eyesconverge and partially cross over.
Optic tract: optic fibres beyond the chiasm.
![Page 35: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/35.jpg)
![Page 36: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/36.jpg)
W. W. Norton
![Page 37: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/37.jpg)
Visual Perception
The same visual input can result in radically different perceptions.
![Page 38: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/38.jpg)
W. W. Norton
Perceptual Set
How we perceive the stimulus depends on our expectations.
![Page 39: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/39.jpg)
Perceptual Theories
Bottom-up processingTop-down processing
![Page 40: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/40.jpg)
Bottom-up Processing
Feature Analysis process of detecting specific elements
in visual input and assembling them into a more complex form
progression from individual elements to the whole
supported by work of Hubel and Wiesel
![Page 41: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/41.jpg)
Top-Down Processing
Gestalt psychologyStep 1: formulate perceptual
hypothesis about the nature of the stimulus as a whole
Step 2: select and examine features to check hypothesis
Step 3: recognize stimulus
![Page 42: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/42.jpg)
Top-Down Processing
Whole can be greater than the sum of its parts visual illusions take advantage of this most common visual illusion is
televisionsee smooth motion but actually objects just
moving from slightly different positions in successive frames
![Page 43: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/43.jpg)
Gestalt Principles of Top-Down Processing
figure-ground divide visual displays into figure and
ground
![Page 44: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/44.jpg)
![Page 45: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/45.jpg)
Gestalt Principles of Top-Down Processing
figure-groundproximity
things that are near one another seem to belong together
similaritycontinuity
tend to follow in whatever direction they’ve been lead
![Page 46: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/46.jpg)
![Page 47: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/47.jpg)
Gestalt Principles of Top-Down Processing
figure-groundproximitysimilaritycontinuitysimplicityclosure
you may “complete” figures that actually have gaps in them
![Page 48: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/48.jpg)
![Page 49: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/49.jpg)
Visual Perception
Need both top-down bottom-up
![Page 50: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/50.jpg)
Perception of Depth
Monocular depth perceptionBinocular depth perception
![Page 51: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/51.jpg)
Monocular Depth Perception
Van Gogh
1889
The Garden of St. Paul’s Hospital
![Page 52: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/52.jpg)
Monocular Depth Perception
Occlusion (near objects block distant ones)
Relative SizeFamiliar SizeLinear Perspective
![Page 53: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/53.jpg)
W. W. Norton
![Page 54: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/54.jpg)
![Page 55: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/55.jpg)
Monocular Depth Perception
Occlusion (near objects block distant ones)
Relative SizeFamiliar SizeLinear PerspectiveTexture GradientPosition Relative to Horizon
![Page 56: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/56.jpg)
Binocular Depth Perception
Clues about the distance based on the differing views of the two eyes “retinal disparity”
convergence sensing the eyes converging towards each
other as they focus on closer objects
![Page 57: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/57.jpg)
Perceptual Constancy
Tendency to experience a stable perception in the face of continually changing sensory input
table looks like a table no matter what angle
door looks like a door even if partly openfriend does not shrink before your eyes if
walking away
![Page 58: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/58.jpg)
![Page 59: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/59.jpg)
![Page 60: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/60.jpg)
![Page 61: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/61.jpg)
![Page 62: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/62.jpg)
![Page 63: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/63.jpg)
Psychophysics
Vision Audition Touch Chemical Senses KinestheticSystem
VestibularSystem
Our Senses Attention
Sensation and Perception
![Page 64: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/64.jpg)
The Stimulus: Sound
-waves of changing air pressure-generated by vibrating objects
![Page 65: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/65.jpg)
Frequency: Pitch.
Low
High
Frequency = cycles per second (hertz)
20 Hz up to 20,000 Hz
![Page 66: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/66.jpg)
Amplitude: loudness (decibels)
Quiet
Loud:
![Page 67: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/67.jpg)
Sensory Processing in the Ear
External ear - vibration of air moleculesMiddle ear - vibration of moveable bonesInner ear - waves in a fluid
converted to stream of neural signals sent to brain
system designed to convert relatively large movements with little force into smaller motions with greater force
![Page 68: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/68.jpg)
W. W
. No r
ton
![Page 69: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/69.jpg)
Inner Ear:
Cochlea:
-circular structure filled with fluid.
![Page 70: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/70.jpg)
-regions of the basilar membrane preferentiallyvibrate in response to sound waves of specific frequencies
33 mm
100 m 500 m
Low FreqHigh Freq
18,000 Hz
50 Hz
![Page 71: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/71.jpg)
-connected to bipolar ganglion cells of the spiralganglion (auditory nerve).
![Page 72: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/72.jpg)
Theories of Auditory Perception
Place theory perception of pitch/frequency
corresponds to vibration of different portions, or places along basilar membrane
![Page 73: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/73.jpg)
Theories of Auditory Perception
Place theoryFrequency Theory
frequency/pitch corresponds to the rate, or frequency, at which the entire basilar membrane vibrates
![Page 74: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/74.jpg)
Theories of Auditory Perception
Place theoryFrequency Theory both are valid in part
sounds under 1000 Hz - frequency theory (entire membrane vibrates)
sounds between 1000 and 5000 Hz - combination
sounds above 5000 Hz - place coding only
![Page 75: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/75.jpg)
Auditory Pathway
1. Cochlear Nuclei:
3. Inferior Colliculus (IC)
4. Medial Geniculate Nucleus (MGN)
5. Auditory Cortex
![Page 76: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/76.jpg)
Auditory Localization
Intensity loss of sound intensity with distance “shadow” effect of head
Timing sound takes longer to reach ear that is
farther away
![Page 77: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/77.jpg)
Primary Auditory Cortex (A1):
-lies along the transverse temporal gyrus.
![Page 78: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/78.jpg)
Tonotopically organized:
-high frequency sounds caudal.-low frequency sounds rostral.
33 mm
100 m 500 m
![Page 79: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/79.jpg)
Organization is not fixed:
2K3K
4K5K
6K2K
3K4K
5K6K
Trained to recognize 4K sound
![Page 80: Sensation and Perception](https://reader035.fdocuments.in/reader035/viewer/2022062309/568135fc550346895d9d7059/html5/thumbnails/80.jpg)
Association Areas:Planum temporale.
-contains Wernicke’s area.-speech comprehension.