pattern recognition
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Pattern Recognition
Nick LundAttention and Pattern Recognition
Introduction
Pattern recognition has been defined as ‘the ability to abstract and integrate certain elements of a stimulus into an organised scheme for memory storage and retrieval’ (Solso,1998).
Features of pattern recognition
Five principles(Solso,1998):
1.Quickly and accurately.
2.Recognise and classify unfamiliar objects.
3.Accurately recognise shapes and objects from different angles.
Features of pattern recognition
4.Identify patterns and objects even when partly hidden.
5.Recognise patterns quickly,with ease,and with automaticity.
Features of pattern recognition
Template matching theories
Feature analysis
Prototype theories
Top-down and bottom-up processing
An examination of the theories of pattern recognition raises the question of whether pattern recognition involves top-down or bottom-up processing.
Bottom- up process
Template matching theoryGeons (Structural- description theory)Feature theoryPrototype theory
Template matching theory
External stumuli matches internal templateVast numbers of templates are storedTemplates are created by experience– E.x.: visit Russia
Problems:– 1) Only occurs when there’s a one-to-one match
• Payne and Wenger (1998)
A
A
AA
2) Where are all these templates stored?
3) Slow process
Ex.: recognize 1000-1500 letters a minute
4) To recognize new variations of a pattern (Solso, 1998)
Geons (Structural- description theory)
Biederman (1987)
Limited number (24) of simple geometric shapes , or geons for us to analyse patterns.– Ex.: mug v.s. bucket
Geons
Advantage:– Recognize pattern from different angles
Disadvantage:– Can’t explain why we recognize a particular
chair.– Ex.: My face v.s. my friend’s face
Feature theory
Patterns are recognized by analysis of the individual features of the pattern.– Ex.: MANGO
M
A
Four stages of pattern recognition– Image demons: record the image and pass it– Feature demons: analyse the image for specific
feature• Ex.:
Pandemonium model (Selfridge, 1959)
– Cognitive demons: detect the present feature and shout
– Decision demons: pick up the loudest feature
Advantage:
More flexible than template theory– Ex.: A , regardless of size, shape or
orientation– Neisser: M → N H M V → longer RT (more distracter) M → O M Q G → shorter RT
Disadvantage:
1) Fail to account for the effects of context and expectations
– Ex.:2) Two experiments which can’t explain feature
theorya. Fail to detect “t” in “the” (Healy)b. Teacup, eyebrow → cup, eye ; eac, ebr (Inhoff
and Topolski)
3) Eysenck and Keane:– How can we recognize patterns when their
features are hidden from view?4) Relationship between the features
– Ex. : T v.s. L
The biology of feature theory
Hubel and Wiesel (1959)In visual cortex:– Simple cells: particular orientation, specific
location– complex cells: lines or edges, in all visual field– Hypercomplex cells: length and angles,
combination of features
Disadvantage:
1) Some questioned the existence of hypercomlex cells
2) How specialized they need to be?3) Run out of cells
Prototype theoryExternal stimuli matches with internal abstract prototype
– Ex.: R, compare to all other “R”s
Solso(1998): two theoretical models①Central-tendency model:
– The average, mean②Attribute-frequency model:
– Most common combination, mode
Advantage:
1) More “economical” than template theory– Don’t need templates for every shape, size,
orientation
2) Explain the speed of recognition of letters, words and patterns / novel stimuli
Disadvantage:
1) can’t explain the effect of context (Eysenck, 1993)
– old woman v.s. young lady
2) B, R, P have similar prototype
Top-down processing
Word superiority effect Rat-Man demonstration
Rat-Man demonstration
Rat-Man demonstration
Rat-Man demonstration
The effect of context
Pattern Recognition
Theories– Template matching– Feature analysis
– Prototype Central-tendencyAttribute- frequency
Summary
Summary
Top-down processing
Bottom- up processing
Word superiority effect
Rat-Man demonstration
Geons
Pandemonium model
THE END