The Sensory Modalities
Lecture 11
1
Learning as Cognition
• Not Just a Change in Behavior
• Change in Knowledge About the World
– Predict Events
– Control Events
2
Cognition
• Basis of Intelligent Behavior
– Beyond Reflex, Taxis, and Instinct
– Beyond Conditioned Response
• Acquire Knowledge About World
– Integrate with Prior Knowledge
– Store Knowledge in Memory
• Use Knowledge in Action
– Cope, Achieve
• Language as a Tool
– Thought, Communication
3
How Do We Know the World?
• Nativism (Descartes)
– Innate Knowledge
• Independent of Sensory Experience
• Empiricism (Locke)
– Knowledge Acquired Through Experience
– Reflections on Experience
• Synthesis (Kant)
– Knowledge Acquired Through Experience
– Presumes Categories of Thought
4
Acquiring Knowledge
Through Experience
• Sensation
– Is There Something Out There?
– How Intense Is It?
• Perception
– Where Is It?
– What Is It Doing?
– What Is It?
• What Can I Do With It?
• What Can It Do to Me?
5
Relations Between Sensation, Perception
• Distal Stimulus
• Proximal Stimulus
Light
Sound
Touch, Smell, Taste
• Transduction
• Neural Impulse
• Mental Representation
– of Distal Stimulus
Back Into Nature
• Object, Event
• Stimulus Energy
– Radiated
– Reflected
• Sensory Receptor
• Transmitted to Cortex
• Object, Event
– Physical Features
– Meaning, Implications
How Do We Get
From the Stimulus to the Percept?
6
Aristotle’s Five Senses
De Anima (4th c. BCE)
Vision
Audition
Olfaction
Gustation
Touch
7
The Sensory Modalities
Sherrington (1906)
Exteroception
• Distance Senses
– Vision
– Audition
• Chemical Senses
– Gustation
– Olfaction
Proprioception
• Kinesthesis
• Equilibrium (Vestibular)
• (Skin Senses)
– Touch
– Temperature
– Pain
• Skin (Cutaneous) Senses
– Touch (Tactile)
– Temperature (Thermal)
– Pain (Nociception)
Interoception
8
Defining the Sensory Modalities
•
•
•
•
Proximal Stimulus
Receptor Organ
Sensory Tract
Projection Area
9
Vision
• Proximal Stimulus
– Electromagnetic Radiation
• 380-780 Nanometers
– Retinal Image
• Receptor Organ
– Rods and Cones in Retina
• Sensory Tract
– Optic Nerve (II)
– Lateral Geniculate Nucleus (Thalamus)
• Primary Visual Cortex (V1)
– Brodmann’s Area 17 (Occipital Lobe)
10
Details of the Visual System
11
Audition
• Proximal Stimulus
– Mechanical Vibration
• 20-20,000 cycles per second
• Receptor Organ
– Cochlea
• Basilar Membrane
• Hair Cells
• Sensory Tract
– Vestibulo-Cochlear Nerve (VIII)
• Auditory Component
– Medial Geniculate Nucleus (Thalamus)
• Primary Auditory Cortex A1
– Brodmann’s Area 41 (Temporal Lobe)
12
Details of the Auditory System
13
Gustation
• Proximal Stimulus
– Chemical Molecules in Food, Drink
• Dissolved in Saliva
• Receptor Organ
– Papillae (Taste Buds)
• Sensory Tract
– Glossopharyngeal Nerve (IX)
– Facial Nerve (VII), Vagus Nerve (X)
• Primary Gustatory Cortex
– Frontal Lobe
• Anterior Insula, Frontal Operculum
– Somatosensory Cortex
14
UCLA
Olfaction
• Proximal Stimulus
– Chemical Molecules in Air
• Dissolved in Mucous
• Receptor Organ
– Olfactory Epithelium
• Sensory Tract
– Olfactory Bulb
– Olfactory Nerve (I)
• Primary Olfactory Cortex
– Prepyriform Cortex
– Periamygdaloid Complex
15
Touch (the Tactile Sense)
• Proximal Stimulus
– Mechanical Pressure on Skin
• Mechanoreceptors
– Free Nerve Endings
– “Basket” Endings, Merkel’s Disks
– Meissner’s / Pacinian Corpuscles
• Sensory Tract
– Afferent Tract
• Spinal, Cranial Nerves
• Spinal Cord
• Primary Somatosensory Cortex
– Brodmann’s Areas 1, 2, 3
16
Temperature (The Thermal Sense)
• Proximal Stimulus
– Temperature Differential
• Receptor Organ
– Krause End-Bulbs
– Ruffini End-Organs
• Sensory Tract
– Spinal Nerves
– (Afferent) Cranial Nerves
• Primary Somatosensory Cortex
– Brodmann’s Areas 1, 2, 3
17
Cutaneous Pain (Nociception)
• Proximal Stimulus
– Injury/Destruction of Tissue
• Inflammation
• Receptor Organs
– Free Nerve Endings
• A-delta fibers, C fibers
• Sensory Tract
– Neospinothalamic Tract
– Paleospinothalamic Tract
• Primary Somatosensory Cortex
– Brodmann’s Areas 1, 2, 3
18
The Skin Senses Reviewed
19
Kinesthesis (Movement, Position)
• Proximal Stimulus
– Activity in Skeletal Musculature
• Stretching, Contraction, Movement
• Receptor Organ
– Neuromuscular Spindles
– Neurotendinous (Golgi) Organs
– Nerve Endings in Joints
• Sensory Tract
– Spinal Nerves
– (Afferent) Cranial Nerves
• Primary Somatosensory Cortex
– Brodmann’s Areas 1, 2, 3
20
The Vestibular Sense (Equilibrium)
• Proximal Stimulus
– Gravitational Force on
Otoliths
• Receptor Organ
– Hair Cells
• Vestibular Sac
• Semicircular Canals
• Sensory Tract
– Vestibulo-Cochlear Nerve
(VIII)
• Vestibular Component
Projection Area
• Cerebellum
21
How Do We Know the World?
• Distance Senses
– Vision
– Audition
• Chemical Senses
– Gustation
– Olfaction
• Skin Senses
– Touch (Tactile)
– Temperature (Thermal)
– Pain (Nociception)
• Proprioception
– Kinesthesis
– Equilibrium (Vestibular)
Jan Brueghel the Younger,
An Allegory of the Five Senses (1625)
22
Sensory Experience
Lecture 12
1
Recap:
Defining the Modality of Sensation
•
•
•
•
Proximal Stimulus
Receptor Organ
Afferent Tract
Projection Area
2
Defining a Sensory Modality
by Proximal Stimulation
•
•
•
•
•
•
•
•
•
Vision
Audition
Olfaction
Gustation
Touch
Temperature
Pain
Kinesthesis
Equilibrium
Rods, Cones in Retina
Hair Cells in Cochlea
Olfactory Epithelium
Taste Buds
Cutaneous Receptors
Krause bulbs, Ruffini organs
A-delta, C fibers
Spindles, Golgi Organs
3
Hair Cells in Inner Ear
Problems for the Traditional View
• Non-Normative Stimulation
• Electrical Stimulation
– Sensory Receptors
– Sensory Nerves
4
The Doctrine of Specific Nerve Energies
Muller (1826)
• The Modality of Sensation is not
Determined by the Proximal Stimulus.
• Each Sensory Nerve Reacts Differently
to Stimulation.
• The Modality of Sensation is
Determined by the Specific Nerve
Activated by the Stimulus
5
Problems with the Original Doctrine
• No Specific “Nerve Energies”
– Adrian (1915)
• Electrical Stimulation of Projection Areas
– Penfield (1945)
6
The Doctrine of Specific Nerve Energies
Muller (1826), modified by Sperry (1945)
• Modality of sensation not determined by
the proximal stimulus or the sensory
receptor.
• Each sensory nerve reacts differently to
stimulation.
– Muller: Modality of sensation is determined
by the activation of modality-specific nerves
– Sperry: Modality of sensation is determined
by the projection area to which the sensory
impulse is delivered
7
Defining a Sensory Modality
by Projection Area
•
•
•
•
•
•
•
•
•
Vision
Audition
Olfaction
Gustation
Touch
Temperature
Pain
Kinesthesis
Equilibrium
Primary Visual Area
Primary Auditory Area
Primary Olfactory Cortex
Primary Gustatory Cortex
Primary Somatosensory Cortex
Somatosensory Cortex
Somatosensory Cortex
Somatosensory Cortex
8
Cerebellum
Qualities of Sensation
Boring (1953)
Intensity
• Vision
– Brightness, Hue, Saturation
• Audition
– Loudness, Pitch, Timbre
• Olfaction, Gustation
– Flavor, Odor
• Touch
– Roughness, Wetness (Pressure, Pain, Warmth)9
The Psychophysical Principle
Every Psychological Quality
of a Sensory Experience
is Related to
Some Physical Property
of the Corresponding Stimulus
10
Qualities of Visual Sensation
• Hue
– Wavelength
465 nm
495 nm
570 nm
• Saturation
– Amount of Gray
700 nm
11
Qualities of Auditory Sensation
Seashore 1938; Howard & Angus (2006)
523
• Pitch
– Frequency
262
• Timbre
131
– Shape of Wave
• Fundamental Frequency
• Distribution of Harmonics
A = 440
– Flute, sine wave
» Pure fundamental
– Oboe, square wave
» Fundamental + Odd harmonics
12
The Doctrine of Specific Fiber Energies
Helmholtz (1863, 1866), after Muller (1826)
Just as Every Modality of Sensation is
Mediated by a Specific Neural System, so…
Within each Modality, Every Quality of
Sensation is Mediated by a Specific Neural
System
13
The Place Theory of Pitch
Helmholtz (1863); Bekesy (1960)
Coat of Arms
Republic of Ireland
Wikipedia
Oval
Window
Higher Pitches
Lower Pitches
14
Duplex Theory of Pitch Perception
Wever & Bray (1930)
• Place Principle
– Above 500-20,000 cps
• Pure Frequency Principle
– Below 1,000 cps
• Volley Principle
– 1,000 – 4,000 cps
15
The Problem of Color Vision
Newton (1704); Young (1802)
ROY G BIV
• 7 Million Shades of Color
– Hue, Brightness, Saturation
• Pantone: 3,039 Specific Colors
– 300 Shades of Blue
16
The Search for Primary Colors
Young (1802); Maxwell (1855)
• 7 Primaries?
– 4 Primaries?
– 3 Primaries!
The
Color
Circle
• Additive Mixture Adds Colors to Black
– Subtractive Mixture Eliminates Colors from White
17
Trichromatic Theory of Color Vision
Helmholtz (1856-1867), after Young (1802) and Maxwell (1855)
• Any Visible Color can be Produced by
Mixing Three Primary Colors
• Three Kinds of Cones
– “Red”
• Long Wavelengths
– “Green”
• Medium Wavelengths
– “Blue”
• Short Wavelengths
18
Georges Seurat,
“Sunday Afternoon on the Island of La Grande Jatte” (1884-1886)
Art Institute of Chicago
19
Problems with the Trichromatic Theory
• Yellow as Pure Color
– Not Mix of Red and Green
• Two Forms of Color Blindness
– Monochromacy
• Loss of All Color Sensitivity
– Dichromacy
• Protanopia
– Loss of “Red” Receptors
• Deuteranopia
– Loss of “Green” Receptors
• Negative Afterimages
20
Keep Your Eyes Focused On This Image for 60-90 Seconds,
Then Advance to the Next Slide
21
22
Jasper Johns,
“Target” (1974)
Walker Art Center, Minneapolis
23
24
Jasper Johns,
“Target”
25
Jasper Johns, Moratorium (1969)
Fogg Art Museum, Harvard
26
27
Jasper Johns
Flags (1967-1968)
Metropolitan Museum of Art
28
The Opponent-Process Theory
of Color Vision
Hurvich & Jameson (1957), after Hering (1878)
• On the Retina
– Three Types of Cones
• “Blue”, “Green”, “Red”
– One Type of Rod
• Light
• Antagonistic Pairs
– Red-Green
– Yellow-Blue
– Black-White
29
Cortical Determinants
of Sensory Quality
• Auditory Pitch
– Tonotopic Organization of A1
• Visual Hue
– Lateral Geniculate Nucleus
– Area V8
30
Sensory Thresholds
and Signal Detection
Lecture 13
1
Qualities of Sensation
Boring (1953)
• Modality-Specific
– Vision: Hue, Saturation
– Audition: Pitch, Timbre
– Olfaction: Odor
– Gustation: Flavor
– Touch: Roughness, Wetness
– Pain: Sensory Pain (Fast/Slow), Suffering
• General: Intensity
– Vision: Brightness
– Audition: Loudness
2
Thresholds for Conscious Awareness
• Absolute
– Weakest Detectable Stimulus
• Relative
– Smallest Detectable Change
• “Just-Noticeable Difference”
– Absolute Threshold a Special Case
• Isomorphism
– Physical Intensity
– Sensory Intensity
3
Neural Coding of Intensity
• All-of-None Law
• Temporal Summation
Presynaptic Neuron O----------< O----------< Postsynaptic Neuron
• Spatial Summation
Presynaptic Neuron 1 O----------< O >----------O Presynaptic Neuron 2
|
|
|
|
|
^
Postsynaptic Neuron
4
Weber’s Law
Weber (1846)
Change in Intensity (dI)
dI/I
= c
Original
Intensity
Noticeable
Change
10
11
100
110
200
220
25
20
15
10
5
0
10
100
200
Original Intensity (I)
c = 1/10
5
Representative Weber Fractions
for Human Sensation
Geldard (1962)
Modality
Visual Brightness (White)
Lifted Weight
Thermal Pain
Auditory Loudness
Cutaneous Pressure
Smell of Rubber
Taste of Salt
c
1/60
1/50
1/30
1/10
1/7
1/4
1/3
6
Fechner’s Law
Fechner (1860)
S = klogI
10
Sensory
Intensity
0
1
2.5
Intensity of Sensation (S)
Physical
Intensity
1
2.3
2
1.5
1
2
200
2.3
1
0.5
0
-20
100
2
0
0
20
40
60
80
100 120 140 160 180 200
Intensity of Stimulus (I)
k = 1, log = log10
7
Fechner’s Law as Logarithm
Fechner (1868)
S = klogI
Intensity of Sensation (S)
3
3
2.5
2.3
2
2
1.5
1
1
0.5
0
0.1
0
10
Intensity of Stimulus (I)
1000
Physical
Intensity
1
10
100
200
1000
Sensory
Intensity
0
1
2
2.3
3
8
Fechner’s Law
Fechner (1868)
S = klogI
• Sensation Grows More Slowly Than
Stimulation
– Sensory Receptors Compress Stimuli
• Exceptions
– Perceived Length
– Perceived Pain
9
Stevens’ Law
Stevens (1961)
S = kIN
Fechner’s Law
Intensity of Sensation (S)
15
14.14
10
10
5
3.16
Sensory
Intensity
1
10
3.16
100
10
200
14.14
1
0
-20
Physical
Intensity
1
0
20
40
60
80
100 120 140 160 180 200
Intensity of Stimulus (I)
k = 1, N = 1/2
10
Stevens’ Law
Stevens (1961)
S = kIN
Intensity of Sensation (S)
The Case of Length
200
175
150
125
100
75
50
25
10
1
0
-20
-25 0 20 40
200
100
60
80 100 120 140 160 180 200
Intensity of Stimulus (I)
Physical
Intensity
1
Sensory
Intensity
1
10
10
100
100
200
200
k = 1, N = 1
11
Stevens’ Law
Stevens (1961)
S = kIN
The Case of Pain
Intensity of Sensation (S)
3000
2828
2500
2000
Physical
Intensity
1
Sensory
Intensity
1
10
31.6
100
1000
200
2828
1500
1000
1000
500
0
-20
0
1 31.6
20 40
60
80 100 120 140 160 180 200
Intensity of Stimulus (I)
k = 1, N = 3/2
12
Stevens’ Law
Stevens (1961)
• A General Psychophysical Law: S = kIn
• Operating Characteristic of Receptors
– Most Compress Stimulation: n < 1
– Some Expand Stimulation: n > 1
Representative Exponents (n)
Viscosity of silicone Fluid: 042
Brightness of Point Source: 0.5
Loudness of Pure Tone: 0.67
Area of Square 0.70
Length of Line: 1.00
Pressure on Palm: 1.10
Taste of Saccharin: 0.8
Taste of Sucrose: 1.3
Heaviness of Lifted Weight: 1.45
Electric Shock to Fingers: 3.50
13
Signal-Detection Theory
Green & Swets (1966), after Tanner & Swets (1954)
• Discriminate between “Signal” and “Noise”
• Components of Decision
– Sensitivity (Information) – d’
– Bias (Criterion) – β
• Expectation
• Motivation
14
The Signal Detection Paradigm
Green & Swets (1966)
Signal
On
Off
(Catch Trials)
“Yes”
HIT
FALSE ALARM
“No”
MISS
Correct
Rejection
Response
15
An Observer with High Sensitivity
Hit Rate = 100%; False Alarm Rate = 0%
Stimulus
Response
On
Off
“Yes”
50%
0%
50%
“No”
0%
50%
50%
50%
50%
16
An Observer with Less Sensitivity
Hit Rate = 80%; False Alarm Rate = 0%
Stimulus
Response
On
Off
“Yes”
40%
0%
40%
“No”
10%
50%
60%
50%
50%
17
“Liberal” Bias toward Yes
Hit Rate = 80%; False Alarm Rate = 80%
Stimulus
Response
On
Off
“Yes”
40%
40%
80%
“No”
10%
10%
20%
50%
50%
18
“Conservative” Bias toward No
Hit Rate = 30%; False Alarm Rate = 30%
Stimulus
Response
On
Off
“Yes”
15%
15%
30%
“No”
35%
35%
70%
50%
50%
19
Sensitivity + “Liberal” Bias
Hit Rate = 80%; False Alarm Rate = 40%
Stimulus
Response
On
Off
“Yes”
40%
20%
60%
“No”
10%
30%
40%
50%
50%
20
Sensitivity + “Conservative” Bias
Hit Rate = 50%; False Alarm Rate = 10%
Stimulus
Response
On
Off
“Yes”
25%
5%
30%
“No”
25%
45%
70%
50%
50%
21
Inducing Liberal Response Bias
by Decreasing Catch Trials
Stimulus
Response
On
Off
“Yes”
52%
18%
70%
“No”
18%
12%
30%
70%
30%
100%
22
Inducing Conservative Response Bias
by Increasing Catch Trials
Stimulus
Response
On
Off
“Yes”
18%
12%
30%
“No”
12%
58%
70%
30%
70%
100%
23
A Balanced Payoff Matrix
Stimulus
Response
On
Off
“Yes”
+25¢
-25¢
0
“No”
-25¢
+25¢
0
0
0
24
A Payoff Matrix
Inducing “Liberal” Bias
Stimulus
Response
On
Off
“Yes”
+25¢
-10¢
+15¢
“No”
0¢
0¢
0¢
25
A Payoff Matrix
Inducing “Conservative” Bias
Stimulus
Response
On
Off
“Yes”
+10¢
-25¢
-15¢
“No”
0¢
0¢
0¢
26
Signal Detection as
Decision Under Uncertainty
• Detection not simply a matter of intensity
– Judgment Under Uncertainty
• Example: Mammography
– Family History
– Cost/Benefit Analysis
• Determinants of Decisions
– Expectations
– Motives
Radiological Society of N.A.
27
Implications of Signal Detection Theory
• Detection Not a Simple Matter of Intensity
• Passive vs. Active Observer
– Expectations, Motives
• “Lower” vs. ‘Higher” Mental Processes
– Proximity to Physical Stimulus
– Ties to Sensory Physiology
• Sensory Detection as Judgment
– Decision-Making
28
Subliminal Perception?
Herbart (1819); Kihlstrom et al. (1992)
• Threshold = Limen
• Conscious Perception
– Conscious Awareness of Distal Stimulus
• Subliminal Perception
– Change in Experience, Thought, or Action
• Attributable to Stimulus
– No Conscious Awareness of Stimulus
– Perception Implied by Changes in Task
Performance
29
Judgment Accuracy
at Zero Confidence
Peirce & Jastrow (1884)
100
% Correct
80
60
40
Chance
20
0
1.06
1.03
1.02
1.015
1.101
1.005
Ratio of Weights
30
Scope of Subliminal Perception
Kihlstrom et al. (1992)
• Methodological Variations
– Weak Intensity
– Short Duration
– “Masking”
– Unattended
• Not Simple Guessing
Prof. Gil Einstein, Furman U.
– Hits > False Alarms
• Analytic Limitation
– Exaggerated Claims for Subliminal Influence 31
The Ecological View
of Perception
Lecture 14
1
Ecological View of Perception
James J. Gibson (1950, 1966, 1979)
Eleanor J. Gibson (1967)
• Stimulus provides information
• Perception involves extracting this
information
• Direct Perception (Direct Realism)
– All information needed for perception is
supplied by the stimulus
– No need for “higher” cognitive activity
– Learn to extract relevant information
• Exploration of object
• All information is available “in the light”
2
Applications of Ecological View
• Motion Perception
– Is the Object Stable or Moving?
• Depth Perception
– Is the Object Near or Far?
• Perception of Plasticity
– Is the Object Rigid or Flexible?
3
The “Stimulus”
in Ecological Perception
• Distal Stimulus
– Object of Regard
• Surrounding Stimulus Field
– Environmental Context
• Exteroceptive Stimuli
– Information from Perceiver’s Body
• Proprioceptive Stimuli
4
Cues for the Perception of Motion
• Successive Covering, Uncovering
5
Covering and Uncovering:
Watch the Red Square
6
Cues for the Perception of Motion
• Successive Covering, Uncovering
• Movement of Image Across Retina
– Holding Head and Eyes Steady
7
Movement of the Retinal Image:
Focus on the Cross
And Hold Your Head and Eyes Steady
+
O
8
Cues for the Perception of Motion
• Successive Covering, Uncovering
• Movement of Image Across Retina
– Holding Head and Eyes Steady
• Egomotion
– Head/Eye Movements
• Alter placement of retinal image
9
Egomotion:
Focus on the Cross, then
Track the Circle with your Eyes
Don’t Move Your Head!
+
O
10
Egomotion:
Focus on the Cross, then
Track the Circle by Moving Your Head
Don’t Move Your Eyes!
O
+
11
An Exercise in Carwatching
• Fixate on target across the street
• Wait for Car to Pass
– Covering and Uncovering
– Movement of Retinal Image
• Follow Passing Car
– With Eyes, Holding Head Steady
– With Head, Holding Eyes Steady
12
Two Systems for Perceiving Motion
Gregory (1966)
Image-Retina
System
Eye/Head
System
13
Conflicting Signals:
The World Moves
Cover one eye with your hand.
Focus other eye on the cross.
Then gently push on your open eye with your finger.
+
14
The Information for Motion:
Discrepancy
• Information provided by image-retina system
– Movement of image across retina
• Information provided by the eye/head system
– Movement of eyes, head, body
15
Image-Retina and Eye-Head Systems
After Coren, Porac, & Ward (1976)
Target
Action of
Eye
Retinal
Image
Command to
Eye (Head)
Perception
of Motion
Image-Retina System
Moving
Stationary
Moves
None
Yes
Eye-Head System
Moving
Tracks
Stationary
Yes
Yes
Stationary
Moves
Moves
Yes
No
Stationary
Pushed
Moves
None
Opposite
Direction
Stabilized
Moves
Stationary
Yes
Same
Direction
16
Binocular Cues for the
Perception of Distance
• Convergence
– Eyes turn inward when focusing on object
– Angle of vectors indicates distance
• up to 30-40 feet
17
18
Palmer, Vision Science
Binocular Cues for the
Perception of Distance
• Convergence
• Retinal (Binocular) Disparity
– Eyes Separated by 2-3 Inches
• Each receives somewhat different image of object
– Stereoscopic Vision
• 2-Dimensional images on retina
• Fused into 3-dimensional image in brain
19
Palmer, Vision Science
20
Different Images: The World Moves
Hold your left index finger at full arm’s length.
Hold your right index finger at half arm’s length.
Close your right eye.
+
Align your two fingers using your left eye.
Both should coincide with cross above.
Then close your left eye and open your right eye.
21
The Stereoscope
22
Monocular Cues for the
Perception of Distance
• Accommodation
– Lens bulges to focus on near objects
– Lens flattens to focus on distant objects
23
24
Palmer, Vision Science
Monocular Cues for the
Perception of Distance
• Accommodation
• Relative Size (the size-distance rule)
– Distance constant, object size = f(image size)
– Size constant, object distance = f(1/image size)
25
26
Palmer, Vision Science
Monocular Cues for the
Perception of Distance
• Accommodation
• Relative Size
• Superposition (Interposition)
– Nearby object cuts off view of more distant object
27
28
Magritte
Carte Blanche
(1965)
National Gallery of Art
29
Monocular Cues for the
Perception of Distance
• Accommodation
• Relative Size
• Superposition
• Linear Perspective
– Vanishing Point
Madonna with Child (13th c.)
Wikipedia
30
Raphael, “The School of Athens” (1510)
“Raphael Rooms”, Vatican City
31
32
Masaccio,
“The Trinity”
(1427)
Basilica of Santa Maria Novella,
Florence
33
Orvieto Cathedral
(14th c.)
LCK
34
Basilica of Santa Maria Novella, Florence
(Alberti, 1458)
LCK
35
Magritte
The Human Condition
(1933)
National Gallery of Art
36
Magritte, The Fair Captive (1931)
Hogarth Galleries, Sydney
37
Magritte
The Promenades of Euclid
(1935)
Minneapolis Institute of Arts
38
Monocular Cues for the
Perception of Distance
•
•
•
•
Accommodation
Relative Size
Superposition
Linear Perspective
• Elevation
– distance from horizon
39
40
Palmer, Vision Science
41
Monocular Cues for the
Perception of Distance
•
•
•
•
•
Accommodation
Relative Size
Superposition
Linear Perspective
Elevation
• Aerial (Atmospheric) Perspective
– Diffraction of Light by Dust, Moisture
– “Bluing” of Distance
42
Blue Ridge Mountains
North Carolina Division of Tourism
Lake Atitlan, Guatemala
Photo by Thor Janson, courtesy of Susan McGovern
Atitlan: Chichicastenango
43
Magritte, The Glass Key (1959)
Menil Collection, Houston
44
Monocular Cues for the
Perception of Distance
•
•
•
•
•
•
Accommodation
Relative Size
Superposition
Linear Perspective
Elevation
Aerial Perspective
• Texture Gradients
45
46
O’Keeffe, “Sky Above Clouds I (1963)
Georgia O’Keeffe Museum
47
O’Keeffe, “Sky Above Clouds I-IV (1963-5)
48
O’Keeffe, “Sky Above Clouds II (1963)
Private Collection
49
O’Keeffe, “Sky Above Clouds III (1963)
Private Collection
50
O’Keeffe, “Sky Above Clouds IV (1965)
Art Institute of Chicago
51
Town Houses, Dublin
LCK
52
Duomo, Arezzo, Italy
LCK
53
Monocular Cues for the
Perception of Distance
•
•
•
•
•
•
•
Accommodation
Relative Size
Superposition
Linear Perspective
Elevation
Aerial Perspective
Texture Gradients
• Shadowing
– Relative positions of shadows
– Distance with respect to light source
54
Palmer, Vision Science
55
56
Illusory Traffic Control
57
Pictorial Cues to Depth and Distance
•
•
•
•
•
•
•
Relative Size
Linear Perspective
Elevation
Superposition
Texture Gradients
Aerial Perspective
Shadowing
58
Motion Cues to Depth and Distance
• Motion Parallax
• Optic Flow
59
Motion Parallax
Gleitman 6e
60
Motion Parallax:
The World Moves Again
Hold your left index finger at full arm’s length.
Hold your right index finger at half arm’s length.
Close your right eye.
+
Align your two fingers using your left eye.
Both should coincide with cross above.
Then move your head back and forth
to the left and right.
61
Optic Flow
Gleitman 6e
62
Organization of Cues
for Depth or Distance
Ocular
Binocular
Monocular
Convergence
Accommodation
Retinal
Disparity
(Stereopsis)
Relative Size
Linear Perspective
Elevation
Superposition
Texture Gradients
Aerial Perspective
Shadowing
Optic Flow
Motion Parallax
From Eyes
Optical
From Light
63
Direct Perception
(Gibson’s “Ecological View”)
• All the information needed for perception
is supplied by the stimulus
– The whole pattern of proximal stimulus
information available in the environment
• Perceptual systems evolved to extract the
stimulation relevant for perception
– Part of innate biological endowment
– Little or no learning, memory
– Little or no reasoning, judgment, inference
64
Perceptual Organization
and Pattern Recognition
Lecture 15
1
Gibson’s “Ecological View”
Direct Perception
• All information needed for perception is
supplied by the stimulus
• Perceptual systems evolved to extract the
stimulation relevant for perception
• Perception is Determined by the Stimulus
– The whole pattern of proximal stimulus
information available in the environment
2
Problems for Ecological Perception
• Conceptual Problem
– Availability vs. Utilization
• Empirical Problems
– Organization
– Pattern Recognition
– Perceptual Constancies
– Ambiguous (Reversible) Figures
– Perceptual Illusions
– Cultural Differences
– Perceptual Problem-Solving
3
Gestalt Principles of Perception
Max Wertheimer (1925); Wolfgang Kohler (1929) ; Kurt Koffka (1935)
• Critique of Structuralism
– Atomism and the Chemical Analogy
• Holism
– Emergent Properties
“The whole is something else
than the sum of its parts”
Koffka (1935)
4
The Law of Prägnanz
(The Minimum Principle)
Hochberg (1974, 1978)
Perception will be as good
as stimulus conditions allow.
We perceive the simplest or most homogeneous
organization that will fit the sensory pattern
5
Classical
Gestalt Principles of Perception
• Proximity
• Similarity
– Color, Size, Orientation
•
•
•
•
•
Common Fate
Symmetry
Parallelism
Good Continuation
Closure
6
Proximity
7
Similarity
8
Common Fate
9
Symmetry
10
Parallelism
11
Closure
12
Good Continuation
13
New
Gestalt Principles of Perception
Palmer (1999)
• Synchrony
• Common Region
• Connectedness
14
Synchrony
15
Common Region
16
Connectedness
17
Subjective Contours
Kanizsa (1976)
18
Information-Processing View
of Perception
Selfridge (1957); Lindsay & Norman (1977)
• Feature Detection
– Analyze Stimulus
– Extract Elementary Features
• Pattern Recognition
– Synthesize Mental Representation
– Familiar, Meaningful Configurations
19
“What the Frog’s Eye
Tells the Frog’s Brain”
Lettvin et al. (1959)
• Present Visual Stimulus
• Record Activity in Optic Nerve
– Single Fiber (or Very Small Bundle)
• Detector Types
– Sustained Contrast
– Net Convexity
– Moving Edge
– Net Dimming
• “Grandmother Cells”?
TheFrog.org
Feature Detectors in Visual Cortex
Hubel & Wiesel (1959, 1962)
• Present Stimuli in Visual Field
• Record Activity in Visual Cortex
– Single Neurons (or Small Bundle)
• Stimulus Features
– Points of Light/Darkness
– Edges
– Bars
– Angle of Orientation
– Movement vs. Stability
– Direction of Movement
21
Hierarchical Organization
of Feature Detectors
Hubel & Wiesel (1959, 1962)
• Simple
– Location of Feature
• Complex
– Presence of Feature
• “Hypercomplex”
– Combinations of Features
22
English Orthography
• Elementary Features
– Vertical, Horizontal, Oblique Lines
– Right, Acute Angles
– Continuous, Discontinuous Curves
A
B O R
23
German Orthography
B
ß
(sisset)
24
Greek Orthography
Γ
Π
Θ
Φ
Ψ
Ω
“gamma”
“pi”
“theta”
“phi”
“psi”
“omega”
25
Russian Orthography
Ж
Ц
Ш
Щ
Ы
Я
“zhe”
“tse”
“sha”
“shcha”
“ee”
“ya”
26
Hebrew Orthography
‫א‬
‫ב‬
‫נ‬
‫ד‬
‫ק‬
‫ש‬
“alef”
“bet”
“nun”
“dalet”
“qof”
“shin”
27
Arabic Orthography
‫إ‬
‫ب‬
‫ت‬
‫ث‬
‫س‬
‫ش‬
“alef”
“beh”
“teh”
“theh”
“seen”
“sheen”
28
Hierarchical Coding of Input in Reading
Graphemic Information
•
•
•
•
•
I
S
R
Q
P
Feature Detectors
• Innate, Automatic
Letter Codes
• Learned
– Initially Effortful
Spelling-Pattern Codes
– Automatized via Practice
Word Codes
Word-Group Codes
29
Articulatory Features in English
•
•
•
•
•
Types of Articulation
Plosives
Nasals
Fricatives
Laterals
Trills
PA vs. BA
TA vs. DA
MA vs. NA
W vs. FA vs. VA
Positions of Articulation
• Bilabial
• Labiodental
• Dental
• Alveolar
• Cacuminal
• Palatal
• Velar
• Glottal
30
Sample Language Differences
in Phonology
• English: 40 phonemes
• Hawaiian: 14 phonemes
– “glottal stop”
• humuhumunukunukuapua'a
• Hawai’i, Kaua’i
• German: ch as in Ach! or Bach
• Russian: Щ, shcha
• Khoisan: ǃ and ǂ, “click”
31
“Bottom-Up” Processing in Perception
After Marr (1982)
Category
• Bottom-Up Processing
– Data-Driven
• Perceptually Driven
Object
– Input: Low-Level Representation
– Output: Higher-Level Representation
Visible Surface
32
Retinal Image
The Word-Letter Phenomenon
Johnston & McClelland (1974), after Reicher (1969), Wheeler (1970)
• Word Superiority Effect
– COIN vs. JOIN > C vs. J
• Detect Letter in 4-Letter String
– Words (COIN) vs. Random Strings (CPRD)
• Instructional Conditions
– “Try to see the whole word”
– “Fixate on particular letter position”
33
The Word-Letter Phenomenon
Johnston & McClelland (1974), after Reicher (1969), Wheeler (1970)
80
78
% Correct
76
74
Letter
72
Whole
70
68
66
Words
Random
String Type
34
“Top-Down” vs. “Bottom-Up”
Processing in Perception
After Marr (1982)
• Bottom-Up Processing
Category
– Data-Driven
• Perceptually Driven
– Input: Low-Level Representation
– Output: Higher-Level Representation
Object
• Top-Down Processing
– Conceptually Driven
• Hypothesis-Driven
• Expectation Driven
Visible Surface
– Input: Higher-Level Representation
– Output: Lower-Level Representation
35
Retinal Image
Size Constancy
36
Shape Constancy
37
Perceptual Constancies
• Pattern of proximal stimulation changes
– Retinal image gets larger
• Perception of distal stimulus is constant
– Object perceived as getting closer
– Perceived size stays the same
38
Figure and Ground in Size Constancy
39
Two Sources of Constancy
• Gibson: Ratios
– Comparison of object with background
– Consistent with ecological view
• All information needed by stimulus
• Helmholtz: Unconscious Inferences
– Unaware of Performing Calculations
– Cannot Specify What They Are
• Know operation only by inference
40
The Constructivist View
of Perception
Lecture 16
1
Problems for Ecological Perception
• Conceptual Problem
– Availability vs. Utilization
• Empirical Problems
– Organization
– Pattern Recognition
– Perceptual Constancies
– Ambiguous (Reversible) Figures
– Perceptual Illusions
– Cultural Differences
– Perceptual Problem-Solving
2
Perception as Construction
The perceiver must go
“beyond the information given”
by the stimulus
Jerome Bruner (1973)
• Conditions
– Stimulus information insufficient for perception
– Stimulus information is misleading
• Perception is intelligent
– Problem-Solving Activity
– Requires knowledge of the world
– Entails judgment, inference, reasoning
3
The Constructivist Tradition
in Perception
Hermann von Helmholtz
Richard Gregory
Irvin Rock
Julian Hochberg
4
The Rubin Vase
Rubin (1915)
5
Silver Jubilee
of
Queen Elizabeth II
6
The Necker Cube
Necker (1832)
7
The Schröder Staircase
Schröder (1854)
8
The “Antioch Cube”
Gombrich (1960)
9
10
San Giovanni Laterno
Rome, c. 1587
11
The “Boring” Figure
Boring (1930); Puck (1915)
12
The Jastrow Figure
Jastrow (1899, 1900)
Harper’s Weekly (1892); Die Fliegende Blatter (1892)
13
Ambiguous Figures
Reversible Figures
Bistable Figures
• Pattern of proximal stimulation constant
– Retinal image doesn’t change
• Perception of distal stimulus is changes
– Mental representation does change
14
MC. Escher
15
Salvador Dali
16
“Slave Market
with Disappearing Bust of Voltaire”
Dali (1940), after Houdon (1778)
17
The Müller-Lyer Illusion
Müller-Lyer (1889)
18
The Müller-Lyer Illusion
Müller-Lyer (1889)
19
Muller-Lyer Illusion
20
Muller-Lyer Illusion
21
The Ponzo Illusion
Ponzo (1913)
22
The Ponzo Illusion
Ponzo (1913)
23
The Ebbinghaus Illusion
Ebbinghaus (1897); aka “Titchener Circles” (1901)
24
Parallel Lines Illusions
Hering (1861); Wundt (1897)
25
The Poggendorf Illusion
Poggendorff (1860), after Zollner (1860)
26
The Poggendorf Illusion
Poggendorff (1860), after Zollner (1860)
27
The Poggendorf Illusion
and the Union Jack
Poggendorff (1860), after Zollner (1860)
J.D.A. Wiseman
28
Horizontal-Vertical Illusion
Wundt (1858), after Fick (1851)
29
Gateway Arch, St. Louis
Eero Saarinen (1947)
30
Unconscious Inference in Illusions
• Upper line appears farther away
– Size an inverse function of distance
• Retinal image same size as lower line
• Therefore the upper line must be longer than
the lower line
Unconscious inferences represent
“going beyond the information given”
31
The Moon Illusion
Kaufman & Rock (1962); Rock & Kaufman (1962)
32
33
How the Ames Room Works
Ames (1934-1935)
34
Distance Cues and Unconscious
Inference in the Ames Room
• Lack of distance cues
– Misleading stimulus
information
• Unconventional geometry
– Inappropriate expectations
• No compensation for
differences in retinal size
35
“Shiprock” or “Rock with Wings”?
Tse’Bit’Ai
36
37
Two Views of the
Arizona Whale-Kangaroo
Canonical
Noncanonical
38
Comparative Frequency of Percept
Kihlstrom, Peterson, et al. (2006)
Whale
Kangaroo
% of Subjects
100
80
60
40
20
0
Noncanonical
Canonical
Noncanonical
Canonical
Orientation of Kangaroo
American
Australian
39
Constellations as Percepts
Orion, Taurus, and Friends
40
Japan Aerospace Exploration Agency
Perceptions
of
Ursa Major
Japan Aerospace Exploration Agency
Carl Sagan, Cosmos
41
A “Gestalt” Figure
42
Gestalt Completion Test
Street (1931)
43
Gestalt Completion Test
Street (1931)
44
Gestalt Completion Test
Street (1931)
45
Gestalt Completion Test
Street (1931)
46
“Canali”
On Mars
Schiaparelli (1880s)
Sheehan (1988)
Sheehan & O’Meara (2001)
47
“Canals”
on Mars
Lowell (1894)
Sheehan (1988)
Sheehan & O’Meara (2001)
48
Mars: The View from Mariner
NASA, 1960s
Sheehan (1988)
Sheehan & O’Meara (2001)
49
Contrasting Views of Perception
• Ecological View
– Perception given by information in stimulus
– Perceive the world, as it is, directly
• Constructivist View
– Perception “goes beyond the information given”
– Actively construct mental representation of world
50
Perception as Problem Solving
• Sources of Information
– Proximal Stimulus (“Bottom-Up”)
• figure, ground
• primary, secondary modalities
– Schemata (“Top-Down”)
• world knowledge
• expectations, beliefs
• Inferential Rules
– Unconscious inferences
– Conscious problem-solving
51
The Perceptual Cycle
Neisser (1976)
Object
Modifies
Modifies
(Accommodation)
(Assimilation)
Action
Schema
(Knowledge,
Expectations,
Beliefs)
Directs
(Thought,
Behavior)
“Perception is where cognition and reality meet”
52
Perceptual Hypothesis-Testing
• Perceptual Cycle Begins
– Mismatch between object and schema
• … Continues
– Assimilation of object to schema
– Accommodation of schema to object
• … Completed
– Object identified, categorized
• … Begins Anew
– New surprising event
53
Perceptual Hypothesis-Testing
• If Stimulus Information Rich, Structured
– Perception is Automatic
• If Stimulus Information Vague, Fragmentary
– Perception Requires Active Problem-Solving
• Percept as Compromise
– Between Expectations, Reality
• Constructive Alternativism
– Different Perceptions of Same Object, Event
54
Perception as Effort After Meaning
Bartlett (1932)
• Constructive Activity
– “Build Up” Mental Representation of World
– Test a Hypothesis About the World
• Goes “Beyond the Information Given”
– Draws on Memory
– Invokes Judgment, Reasoning, Inference
55