CS 182
Sections 103 - 104
slides created Eva Mok
(emok@icsi.berkeley.edu)
Feb 22, 2006
(http://www.ritsumei.ac.jp/~akitaoka/color-e.html
Announcements
• a3 part 2 due tonight, Feb. 22nd, 11:59pm
• my office hours have moved to 2 Evans
• I have some of yr quizzes
Quick Recap
• Last Week
– Finished up backprop and neural networks
– Color: neurophysiology, psychophysics, etc.
• This Week
– Imaging techniques (fMRI, etc.)
– Categories & concepts
• Coming up
– Image Schemas, Force-Dynamics
Quiz!
1. How do humans detect color biologically?
2. Are color names arbitrary? What are the findings
surrounding this?
3. What constitutes a basic-level category? Is red a
basic-level category? Is maroon?
4. Why does it take longer to determine whether “100
is close to 99” than “99 is close to 100”?
Quiz!
1. How do humans detect color biologically?
2. Are color names arbitrary? What are the findings
surrounding this?
3. What constitutes a basic-level category? Is red a
basic-level category? Is maroon?
4. Why does it take longer to determine whether “100
is close to 99” than “99 is close to 100”?
A Tour of the Visual System
• two regions of interest:
– retina
– LGN
Rods and Cones in the Retina
http://www.iit.edu/~npr/DrJennifer/visual/retina.html
The Microscopic View
What Rods and Cones Detect
Notice how they aren’t distributed evenly, and the
rod is more sensitive to shorter wavelengths
Center / Surround
• Strong activation in center,
inhibition on surround
• The effect you get using these
center / surround cells is
enhanced edges
top:
the stimuli itself
middle:
brightness of the stimuli
bottom: response of the retina
• You’ll see this idea get used in
Regier’s model
http://www-psych.stanford.edu/~lera/psych115s/notes/lecture3/figures1.html
How They Fire
• No stimuli:
– both fire at base rate
• Stimuli in center:
– ON-center-OFF-surround
fires rapidly
– OFF-center-ON-surround
doesn’t fire
• Stimuli in surround:
– OFF-center-ON-surround
fires rapidly
– ON-center-OFF-surround
doesn’t fire
• Stimuli in both regions:
– both fire slowly
Color Opponent Cells
25
50
Mean Spikes / Sec
+R-G
• These cells are found
in the LGN
+Y-B
• Four color channels:
Red, Green, Blue,
Yellow
25
400
700
50
• R/G , B/Y pairs
+G-R
400
25
700
25
• We can use these to
determine the visual
system’s fundamental
hue responses
+B-Y
400
700
400
Wavelength (mμ)
(Monkey brain)
• much like
center/surround cells
700
Quiz!
1. How do humans detect color biologically?
2. Are color names arbitrary? What are the findings
surrounding this?
3. What constitutes a basic-level category? Is red a
basic-level category? Is maroon?
4. Why does it take longer to determine whether “100
is close to 99” than “99 is close to 100”?
The WCS Color Chips
• Basic color terms:
–
–
–
–
Single word (not blue-green)
Frequently used (not mauve)
Refers primarily to colors (not lime)
Applies to any object (not blonde)
FYI:
English has 11
basic color terms
Results of Kay’s Color Study
Stage I
II
IIIa / IIIb
IV
V
VI
VII
W or R or Y
W
W
W
W
W
W
Bk or G or Bu
R or Y
R or Y
R
R
R
R
Bk or G or Bu
G or Bu
Y
Y
Y
Y
Bk
G or Bu
G
G
G
Bk
Bu
Bu
Bu
Bk
Bk
Bk
Y+Bk (Brown)
Y+Bk (Brown)
W
R
Y
R+W (Pink)
Bk or G or Bu
R + Bu (Purple)
R+Y (Orange)
B+W (Grey)
If you group languages into the number of basic color terms
they have, as the number of color terms increases,
additional terms specify focal colors
Quiz!
1. How do humans detect color biologically?
2. Are color names arbitrary? What are the findings
surrounding this?
3. What constitutes a basic-level category? Is red a
basic-level category? Is maroon?
4. Why does it take longer to determine whether “100
is close to 99” than “99 is close to 100”?
Categories & Prototypes: Overview
Superordinate
Furniture
Sofa
leather
sofa
fabric
sofa
Basic-Level Category
Desk
L-shaped
desk
Reception
disk
Subordinate
• Three ways of examining the categories we form:
– relations between categories (e.g. basic-level category)
– internal category structure (e.g. radial category)
– instances of category members (e.g. prototypes)
Basic-Level Category
What constitutes a basic-level category?
• Communication:
• Perception:
– similar overall
perceived shape
– shortest
– single mental image
– contextually neutral
– (gestalt perception)
– first to be learned by children
– fast identification
– first to enter the lexicon
– most commonly used
• Function:
• Knowledge Organization:
– general motor program
Red? yes
– most attributes of category
members stored at this level
Maroon? arguable (expertise)
Quiz!
1. How do humans detect color biologically?
2. Are color names arbitrary? What are the findings
surrounding this?
3. What constitute a basic-level category? Is red a
basic-level category? Is maroon?
4. Why does it take longer to determine whether “100
is close to 99” than “99 is close to 100”?
Category Structure
• Classical Category:
– necessary and sufficient conditions
• Radial Category:
– a central member branching out to less-central and non-central
cases
– degrees of membership, with extendable boundary
• Family Resemblance:
– every family member looks like some other family member(s)
– there is no one property common across all members (e.g. polysemy)
• Prototype-Based Category
• Essentially-Contested Category (Gallie, 1956) (e.g. democracy)
• Ad-hoc Category (e.g. things you can fit inside a shopping bag)
Prototype
• Cognitive reference point
– standards of comparison
• Social stereotypes
– snap judgments
– defines cultural expectations
– challengeable
• Typical case prototypes
– default expectation
– often used unconsciously in
reasoning
• Ideal case / Nightmare case
– e.g. ideal vacation
– can be abstract
– may be neither typical nor
stereotypical
• Paragons / Anti-paragons
– an individual member that
exhibits the ideal
• Salient examples
– e.g. 9/11 – terrorism act
• Generators
– central member + rules
– e.g. natural number = singledigit numbers + arithmetic
Mother
• The birth model
The person who gives birth is the mother
• The genetic model
The female who contributes the genetic material is the mother
• The nurturance model
The female adult who nurtures and raises a child is the mother of
the child
• The marital model
The wife of the father is the mother
• The genealogical model
The closest female ancestor is the mother
(WFDT Ch.4, p.74, p.83)
Radial Structure of Mother
Genetic
mother
Stepmother
Unwed
mother
Surrogate
mother
Biological
mother
Adoptive
mother
Central
Case
Foster
mother
Birth
mother
Natural
mother
The radial structure of this category is defined
with respect to the different models
Marriage
• What is a marriage?
• What are the frames (or models) that go into defining
a marriage?
• What are prototypes of marriage?
• What metaphors do we use to talk about marriages?
• Why is this a contested concept right now?
Language and Thought
Language
• We know thought (our
cognitive processes)
constrains the way we learn
and use language
• Does language also influence
thought?
• Benjamin Whorf argues yes
Thought
cognitive processes
• Psycholinguistics experiments
have shown that linguistics
categories influence thinking
even in non-linguistics task