Perceptual Processes
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Perceptual ProcessesPerceptual Processes
IntroductionIntroduction Pattern RecognitionPattern Recognition Top-down Processing & Pattern RecognitionTop-down Processing & Pattern Recognition Face PerceptionFace Perception
AttentionAttention Divided attentionDivided attention Selective attentionSelective attention Theories of attentionTheories of attention
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PerceptionPerception
Process that uses our previous Process that uses our previous knowledge to gather and interpret the knowledge to gather and interpret the stimuli that our senses registerstimuli that our senses register
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Pattern RecognitionPattern Recognition
The identification of a complex The identification of a complex arrangementarrangement of sensory stimuliof sensory stimuli
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PatternsPatterns
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Theories of Pattern Theories of Pattern RecognitionRecognition
Template Matching TheoryTemplate Matching Theory
Prototype ModelsPrototype Models
Distinctive Features ModelDistinctive Features Model
Recognition by Components ModelRecognition by Components Model
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Template Matching TheoryTemplate Matching Theory
Compare a new stimulus (e.g. ‘T’ or ‘5’) to Compare a new stimulus (e.g. ‘T’ or ‘5’) to a set of specific patterns stored in memorya set of specific patterns stored in memory
Stored pattern most closely matching Stored pattern most closely matching stimulus identifies it.stimulus identifies it.
To work – must be single matchTo work – must be single match
Used in machine recognitionUsed in machine recognition
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Examples of Template Matching Examples of Template Matching AttemptsAttempts
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Used in machine recognitionUsed in machine recognition
Continue here tuesday
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Problems for Template Problems for Template MatchingMatching
Inefficient - large # of stored patterns Inefficient - large # of stored patterns
requiredrequired
Extremely inflexibleExtremely inflexible
Works only for isolated letters and simple Works only for isolated letters and simple
objectsobjects
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Prototype TheoriesPrototype Theories
Store Store abstractabstract, idealized patterns (or , idealized patterns (or
prototypes) in memoryprototypes) in memory
Summary - some aspects of stimulus Summary - some aspects of stimulus
stored but not othersstored but not others
Matches need not be exactMatches need not be exact
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Examine the faces below, which belong to two different categories.
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PrototypesPrototypes
Family resemblances (e.g. birds, faces, Family resemblances (e.g. birds, faces,
etc.)etc.)
Evidence supporting prototypesEvidence supporting prototypes
Problems - Vague; not a well-specified Problems - Vague; not a well-specified theory of pattern recognitiontheory of pattern recognition
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Distinctive Features ModelsDistinctive Features Models
Comparison of stimulus Comparison of stimulus featuresfeatures to a to a storedstored list of features list of features
DistinctiveDistinctive features differentiate one features differentiate one pattern from anotherpattern from another
Can discriminate stimuli on the basis of a Can discriminate stimuli on the basis of a small # of characteristics – featuressmall # of characteristics – features
Assumption: feature identification possibleAssumption: feature identification possible
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Distinctive Features Models: Distinctive Features Models: EvidenceEvidence
Consistent with physiological researchConsistent with physiological research
Psychological EvidencePsychological Evidence Gibson 1969Gibson 1969
Neisser 1964Neisser 1964
Waltz 1975Waltz 1975
Pritchard 1961Pritchard 1961
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1919
2020
First, scan for the letter ‘Z’ in the first column of letter strings.
Next, scan for the letter ‘Z’ in the second column of letter strings.
Which is easier? Why?
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Letter Detection TaskLetter Detection Task
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T
ZA
How a Distinctive Features Model Might Work:
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Distinctive FeaturesDistinctive Features
Theory must specify how the features are Theory must specify how the features are combined/joinedcombined/joined
These models deal most easily with fairly These models deal most easily with fairly simple stimuli -- e.g. letterssimple stimuli -- e.g. letters
Shapes in nature more complex -- e.g. Shapes in nature more complex -- e.g. dog, human, car, telephone, etcdog, human, car, telephone, etc
What would the features here be?What would the features here be?
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Recognition by Components Recognition by Components ModelModel
Irving Biederman (1987, 1990)Irving Biederman (1987, 1990) Given view of object can be represented Given view of object can be represented
as arrangement of basic 3-D shapes as arrangement of basic 3-D shapes ((geonsgeons))
Geons = derived features or higher level Geons = derived features or higher level featuresfeatures
In general 3 geons usually sufficient to In general 3 geons usually sufficient to identify an objectidentify an object
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Examples of GeonsExamples of Geons
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Status of Recognition by Status of Recognition by Components TheoryComponents Theory
Distinctive features theory for 3-D object Distinctive features theory for 3-D object
recognitionrecognition
Some research consistent with the model; Some research consistent with the model;
some notsome not
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Recognition by ComponentsRecognition by Components Pro – Biederman found that obscuring vertices impairs objects Pro – Biederman found that obscuring vertices impairs objects
recognition while obscuring other parts of objects has a lesser effect.recognition while obscuring other parts of objects has a lesser effect.
Which is easiest to recognize as a cup? The left or right?Which is easiest to recognize as a cup? The left or right?
Con – Biederman – Not all natural objects can bedecomposed into Con – Biederman – Not all natural objects can bedecomposed into geons. What about a shoe?geons. What about a shoe?
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Support for BiedermanSupport for Biederman
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SummarySummary
Distinctive Features approach currently Distinctive Features approach currently strongest theorystrongest theory
Perhaps all 3 approaches (distinctive Perhaps all 3 approaches (distinctive features, prototypes, recognition by features, prototypes, recognition by components) are correctcomponents) are correct
Regardless, pattern recognition is too Regardless, pattern recognition is too rapid and efficient to be completely rapid and efficient to be completely explained by these modelsexplained by these models
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Two types of ProcessingTwo types of Processing
Bottom-up or data-driven processingBottom-up or data-driven processing
Top-down or conceptually driven Top-down or conceptually driven
processingprocessing
Theme 5 -- most tasks involve bottom-up Theme 5 -- most tasks involve bottom-up
and top-down processingand top-down processing
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Thought ExperimentThought Experiment
Assume each letter 5 feature detections involvedAssume each letter 5 feature detections involved
Page of text approximately 250-300 words of 5 Page of text approximately 250-300 words of 5
letters per word on average letters per word on average
Each page: 5 x 5 x 250-300 = 6250 - 7500 Each page: 5 x 5 x 250-300 = 6250 - 7500
feature detectionsfeature detections
Typical reader 250 words/min readingTypical reader 250 words/min reading
6250/60 secs =100 feature detections per 6250/60 secs =100 feature detections per
secondsecond
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Word Superiority EffectWord Superiority Effect
We can identify a single letter more rapidly We can identify a single letter more rapidly and more accurately when it appears in a and more accurately when it appears in a word than when it appears in a non-word.word than when it appears in a non-word.
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Word Superiority- Non-word Word Superiority- Non-word TrialTrial
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Word Superiority: Word TrialWord Superiority: Word Trial
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Single Letter ‘K’ vs ‘K’ in a Single Letter ‘K’ vs ‘K’ in a wordword
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Word Superiority: Single Letter Word Superiority: Single Letter TrialTrial
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Word Superiority: Word TrialWord Superiority: Word Trial
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Altered Sentences in Warren and Warren Altered Sentences in Warren and Warren (1970)(1970)
Sentence that was presented Word Heard
It was found that the *eel was on the axle
It was found that the *eel was on the shoe
It was found that the *eel was on the orange
It was found that the *eel was on the table
wheel
heel
peel
meal
*Denotes the replaced sound
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The Effect of Varying Sentence Frame Context on Interpreting an Ambiguous Stimulus
The __________ raised (________) to supplement his income.
lion tamer
zoo keeper
botanist
dairy farmer
botanist
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The Influence of Stimulus Features & Sentence Context on Word Identification
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AttentionAttention
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Definitions of AttentionDefinitions of Attention
Concentration of mental resourcesConcentration of mental resources
Allocation of mental resourcesAllocation of mental resources
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Divided AttentionDivided Attention
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Reinitz & Colleagues (1974)
Divided Attention Condition
Subjects count the dots
Full Attention Condition
No instruction about dots
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Proportion of Responses that were “old” for Each of Two Study Conditions and Two Test Conditions
(Reinitz & Colleagues, 1994).
Study Condition
TestCondition
Full Attention Divided Attention
Old Face
ConjunctionFaces
.81
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.48
.42
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Divided Attention & PracticeDivided Attention & Practice
Hirst, et. al. 1980Hirst, et. al. 1980
Spelke, 1976Spelke, 1976
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UpsetUpset
HotelHotel
JudgeJudge
EmploymentEmployment
MapMap
IndulgeIndulge
PencilPencil
ProblemProblem
KeyKey
TerribleTerrible
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Selective Selective AttentionAttention
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Selective Attention Selective Attention (Dichotic Listening Task)(Dichotic Listening Task)
ShadowingShadowing
Irrelevant ChannelIrrelevant Channel
Cocktail Party Effect - Morray (1959)Cocktail Party Effect - Morray (1959)
Wood and Cowan (1995)Wood and Cowan (1995)
Treisman (1960)Treisman (1960)
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Dichotic Listening Task
T, 5, H
LEFT
T
5
H
RIGHT
S
3
G
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Cocktail EffectCocktail Effect
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Treisman’s Shadowing Treisman’s Shadowing StudyStudy
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Stroop EffectStroop Effect
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Filter Models of AttentionFilter Models of Attention
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Capacity Model of AttentionCapacity Model of Attention
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Diagnostic Criteria for Automatic and Controlled ProcessesAutomatic Controlled
1. The process occurs withoutintention , wit hout a consciousdecision.
2. the mental process is not open toconscious awareness orintrospection.
3. The process consumes few i f anyconscious resources; that is, itconsumes littl e if any consciousattention.
4. (Informal) The process operatesvery rapid ly, usually w ithin onesecond.
1. The process occurs only withintention , wit h a deli beratedecision.
2. The process is open to awarenessand introspection .
3. The process uses consciousresources; that is, it d rains the poolof conscious attentional capacity.
4. (Informal) The process is relativelyslow, taking more than a second ortw o for completion.
Part ial Autonomy/ AutomaticityA process is said to be partially autonomous if it can begin automatically butrequi res a more conscious set of operations for completion (see Zbrodoff &Logan, 1986).
Diagnostic Criteria for Automatic Processes
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Cerebral Cortex & AttentionCerebral Cortex & Attention
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