Post on 14-Jan-2016
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Psy 260 Announcements
All late CogLab Assignment #1’s due today CogLab #2 (Attention) is due Thurs. 9/21 at
the beginning of class Coglab booklets and disks--along with a
printer that usually works--are available for use in the Psychology Resource Room (enter through Psych B 120)
Quiz alert!
Neural network models
Nodes - processing units used to abstractly represent elements such as features, letters, and words
Links, or connections between nodes Activation - excitation or inhibition that
spreads from one node to another
Word superiority effect, revisited
Cond. 1: Cond. 2: Cond. 3:
WORD ORWD D
XXXXX XXXXX XXXXX
Test: Which one did you see?
K K K
D D D
Word superiority effect, revisited
Word superiority effect, revisited
Word level
Letter level
Feature level
Input
See Reed, p. 36
Word superiority effect: An interactive activation model
WORK
K
| / \
Input: K or WORK or ORWDSee Reed, p. 36
Interactive Activation Model of the word superiority effect (McClelland & Rumelhart, 1981)
Interactive Activation Model of the word superiority effect (McClelland & Rumelhart, 1981)
(Email example of mangled text!!)
James Cattell, 1886: Word superiority effect (Reicher, 1969; Cattell, 1886)
Subjects recognized flashed words more accurately than flashed letters.
He proposed a word shape model.
Evidence for word shape model:
Word superiority effect Lowercase text is read faster than uppercase. Proofreading errors tend to be consistent
with word shape.
Evidence for word shape model:
Word superiority effect Lowercase text is read faster than uppercase. Proofreading errors tend to be consistent
with word shape. It’S dIfFiCuLt To ReAd WoRdS iN
aLtErNaTiNg CaSe.
Perception and Pattern Recognition III:
Faces
How do people recognize faces? Consider these types of theories:
Template theories Feature theories Structure theories Prototype theories
Feature theories
Patterns are represented in memory by their parts.
In perception, the parts are first recognized and then assembled into a meaningful pattern.
Piecemeal (as opposed to holistic)
What are the distinctive features for faces ?
Eyes, nose, mouth - NOT!
What are the distinctive features for faces ?
Eyes, nose, mouth - NOT!
Revisit Eleanor Gibson’s criteria: Each feature should be present in some patterns and
absent in others A feature should be invariant (unchanged) for all
instances of a particular pattern Each pattern has a unique combination of features The number of features should be fairly small
A set of features is evaluated by how well it can predict perceptual confusions.
Who are these people? Same or different?
Who are these people? Same or different?
Inspiration: Caricatures
“More like the face than the face itself” What are the distinctive features of a
face - say, Richard Nixon’s??? Ski jump nose Jowly face Curly-textured hair Receding bays in hairline Boxy chin (David Perkins, 1975)
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
A B C
D E F
Contraindicated features: Worse than missing features (Perkins, 1975)
Revisit: Problems w/ feature theories
How to determine the right set of features?
What about the relationships between features?
What if all the features are present in the pattern, but scrambled?
Features theories predict: No problem!
(and that’s the problem.)
Face recognition is holistic
(Tanaka & Farah, 1993)
Structure theories
Build on feature theories Patterns are represented in memory by
features AND by the relations between them.
Holistic The context of the pattern plays an
important role in pattern recognition.
A structure theory: RBC (Biederman)
Recognition by Components Geons: simple volumes (~35 of them) Construct objects by combining geons
RBC Theory
Analyze an object into geons Determine relations among the geons The relation among geons is critical!
RBC Theory
It’s hard to recognize an object without the information about relations among geons.
Hard!
RBC Theory
It’s hard to recognize an object without the information about relations among geons.
Easier!
RBC Theory
Basic properties of Geons View invariance Discriminability Resistance to visual noise
RBC Theory - Problems
Explains how people distinguish categories of objects (types) - like cups vs. briefcases. But how do people distinguish individual objects (tokens) that come from the same category (like faces)??
Neurons are to tuned respond to much smaller elements than those represented by geons!
Recap so far:
Theory: What it explains:
Template Bar codes (by machines)
Feature Letter learning & confusions
Structural Biederman’s data (geons)
Prototype
Face recognition (Piecemeal or holistic?)
(A “special” case of pattern recognition?)
We see faces everywhere.
Image from
Mars’ surface
by Viking Orbiter 1
(Mcneill, 1998, p. 5)
Are faces “special”?
How many faces can you recognize?
Are faces “special”?
How many faces can you recognize? Gibson: Patterns are easier to encode
as faces than as writing
Are faces “special”?
How many faces can you recognize? Gibson: Patterns are easier to encode
as faces than as writing
Faces vs. writing
Are faces “special”?
How many faces can you recognize? Gibson: Patterns are easier to encode
as faces than as writing Prosopagnosia
We don’t need much information to recognize a familiar face.
Guess who?
We don’t need much information to recognize a familiar face.
Guess who?
Why is face recognition so interesting?
It’s important! Faces are highly similar to one another. Yet we’re really good at it: we can tell an
astounding number of faces apart. Not all facial information is created equal. Could machines ever do as well as people?
Or even better? Are faces somehow “special”?
Why is face recognition so interesting?
It’s important! Faces are highly similar to one another. Yet we’re really good at it: we can tell an
astounding number of faces apart. Not all facial information is created equal. Could machines ever do as well as people?
Or even better? Are faces somehow “special”?
Faces are hard to recognize in photographic negative
(Galper & Hochberg, 1971)
Faces are hard to recognize upside down (Yin, 1969)
Faces are hard to recognize upside down (Yin, 1969)
“Early processing in the recognition of faces”
http://www.diss.fu-berlin.de/2003/35/Kap4.pdf
Faces are hard to recognize upside down (Yin, 1969)
“Early processing in the recognition of faces”
http://www.diss.fu-berlin.de/2003/35/Kap4.pdf
Margaret Thatcher effect
(Thomson, 1980)
Margaret Thatcher effect
(Thomson, 1980)
Why?
The configural processing hypothesis:
When faces are inverted, the relationships among features are disturbed.
So we don’t notice the odd configuration in the Thatcher illusion.
(Bartlett & Searcy, 1993)
Faces are hard to recognize upside down (Yin, 1969)
“Early processing in the recognition of faces”
http://www.diss.fu-berlin.de/2003/35/Kap4.pdf
What kind of theory accounts for face recognition?
Theory: Objection:
Template Different lighting, orientation,
motion, hair, glasses, age
Feature What is a facial “feature”?
Invariant vs. transient features
Structural
Prototype
Familiar vs. unfamiliar faces
“Attribute Checking Theory” A feature theory For familiar faces, internal features seem
to be more important than outside features. For new faces, we pay more attention to
outside features (hair, face shape, etc.)
(Bradshaw & Wallace)
Familiar vs. unfamiliar faces
“Early processing in the recognition of faces”
http://www.diss.fu-berlin.de/2003/35/Kap3.pdf
Children recognize faces differently than adults do.
Children under 10 use transient features to distinguish unfamiliar faces. Strangers wearing the same hat seem
similar, and are confusable.
(Susan Carey)
What makes faces confusable?
(Harmon, 1973)
Application: Face recognition by eyewitnesses
Problem:
Identikit: piecemeal, featural Photo methods: Introduce interference, bias Lineup: when the perpetrator is not present,
20-40% of witnesses select someone anyway. With photos and lineups, witnesses compare
the suspects and choose the most similar one False convictions often have eyewitness
testimony as the strongest evidence in the
The right way to do a lineup:
“Showup” - view suspects or pictures one at a time, ideally only once
If multiple viewings, then view each one the same number of times, always in random order (avoid between-suspect comparisons)
The one showing the faces must be blind to whom law enforcement believes suspect is
(Otherwise, impossible to avoid bias) Then false IDs drop to 10%.
Mistaken identity!
What about a structural theory of face recognition?
Pro: The relationships between features are very important.
Pro: We often fail to recognize a familiar face when we see it out of context.
Con: A structural theory doesn’t explain how we can distinguish so many highly similar, individual tokens.
(Moving right along: A prototype theory
What is a caricature?
An exaggerated representation of a face More like a face than the face itself!
The Caricature Generator (Brennan, 1982)
The average (prototype) face
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Veridical (traced) drawing
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Veridical (traced) drawing
Ronald Reagan
QuickTime™ and aTIFF (LZW) decompressor
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A prototype theory of face recognition
When drawings were recognized, caricatures were faster than veridical drawings, which were faster than “anti-caricatures.”
Average face 0 distortion Caricature
(Rhodes, Brennan, & Carey, 1987)
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
50% Caricature
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Caricatures
&
Anti-Caricatures
For a face,maybe we encodethe difference froma prototype.
Face Space
What kind of theory accounts for face recognition?
Theory: Objection:
Template Different lighting, orientation, motion, hair, glasses, age
Feature What is a facial “feature”?Invariant vs. transient features
Structural Faces are highly similar tokenswith the same structure!
Prototype This works! (but maybe not for unfamiliar faces and not
for kids)
Is face recognition “special”?
No! There are other classes of patterns for
which people can distinguish huge numbers of individuals (tokens). Ornithologists recognize individual birds New England Kennel Club judges
recognize individual dogs There is even prosopagnosia for things
other than faces!
Some sources
George Lovell’s slides from Roth & Brucehttp://www.face-rec.org/interesting-papers/Other/FaceRecognition.pdf
“Early processing in the recognition of faces”http://www.diss.fu-berlin.de/2003/35/Kap3.pdf
Harmon, L. D. (1973). The recognition of faces. Scientific American, 229(5), 71-82.