outline »visual pattern recognition ◊template theory ◊feature theory ◊top down influences...

• Outline» Visual Pattern recognition

◊ Template theory◊ Feature Theory◊ Top down influences

» Object recognition » Auditory Pattern recognition

◊ Physiology of hearing◊ Echoic Memory

» Video: A face in the mirror

Study Question.• Compare and contrast template and feature theories of pattern recognition.• Compare and contrast visual (iconic) and auditory (echoic) memory.

04/20/23

Pattern Recognition

• Features Theories» Complex stimuli are composed of distinctive and

separable parts called features

Pattern Recognition

• Features and form perception

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Pattern Recognition

• Feature search: Find the green ‘T’

Pattern Recognition

• Conjunction search: Find the green ‘T’

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Pattern Recognition

• E. Gibson’s Feature Theory» Complex stimuli are composed of distinctive and separable parts

called features.

» Pattern recognition is accomplished by counting the presence or absence of a checklist of features.

» Gibson’s specification of the feature set◊ Features must be critical

◊ Identity should be unchanged by brightness, size and perspective.

◊ Yield a unique pattern for each letter

◊ As small a set as possible.

Find the letter ‘W’

Group B

SSGQOPBCPOSCCGQOPSBDDBOPPCQDPOOCGPQOOCCGSPOCSDSGCOOQGGSOOPQQDSSOPOQSOWCBQGGS

BQGSCOPODSOPSSGQOPBCPOSCCGQOPSBDDBSDSGCOOQGGS

Group A

MNNXKLKNLKKMMXNNKMM LKNMXMMKMYMNZNXKXXLMMKYZXZMZXMZXNMXYNKMKMNKWMNXLKKZXMNXXNMLMNNXKLKNLKKMMXNNKMMLKNMXMMKM

• Other evidence for feature theory: Stabilized retinal

images.

- Physiological nystagmus

• Other evidence for feature theory: Stabilized retinal

images.

- Physiological nystagmus

• Other evidence for feature theory: Stabilized retinal

images.

- Physiological nystagmus

• Other evidence for feature theory: Stabilized retinal

images.

- Physiological nystagmus

• Other evidence for feature theory: Stabilized retinal

images.

- Physiological nystagmus

• Other evidence for feature theory: Stabilized retinal

images.

- Physiological nystagmus

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Pattern Recognition

• Problems with Feature theory» How features go together are as important as the features

themselves.

Pattern Recognition

• Structural Theories» Like feature theories, except that they also consider the

structure of the features (i.e., How they go together.» Biederman’s Theory of 3-d object recognition.

◊ Geons: 3-D ‘volume’ features

Pattern Recognition

» Eliminating information about the relationship between volumes/features should be detrimental to pattern recognition.

◊ E.g.,

-> What are these objects?

Recognition accuracy

70 %50 % 100 %

Pattern Recognition

• Pandemonium

Pattern Recognition

• The word superiority effect

R A I D

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Pattern Recognition

• The word superiority effect

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R U E D

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-> It is easier to identify a letter in the context of a word than by itself.

Pattern Recognition

• Bottom-up processing» “The whole is greater than the sum of its parts”» Perception involves an interplay between bottom-up and

top-down processes.

Top-down processes

• Perception requires an interplay between top down and bottom up processes

E.g.,

Cxn xox rxax txix oxe xhxcx hxs xvxrx oxhxr xextxr xixsxnx?

Thxs oxe ix haxdex bexauxe exerx thxrd xetxer xs mxssxng.

Herx evexy foxrth xettxr hxs bexn rexlacxd.

This xentexce is xasy tx read xven txough xvery xifth xettex is goxe

• The interactive - activation model: Bottom-up

“Animal”

MATCAT RAT

M C R

CAT

• The interactive - activation model: Top-down

“Animal”

MAT CAT RAT

M C R

CAT

Pattern Recognition

• Connectionism» The Unit

◊ Activity, weights, thresholds, and summation

» A simple example the AND problem

» The OR problem

» The XOR problem◊ Hidden units and three layered networks.

Auditory Perception

• Physiology of hearing

Psychology 100Intersession

Chap 5

Sensation

Low

High

Com

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sion

Hearing

• The physical stimulus» The quantitative element: Amount of compression (sound pressure).

◊ We hear loudness, measured in decibels.» The qualitative element: Frequency of compression waves.

◊ We hear pitch

SoftLoudQuantitative

Qua

lita

tive

Low

High

Auditory Perception

• Auditory Sensory Memory» Darwin et al.’s partial report experiment

1B4

68C

S 2 7