1. 1 Perceptual Processes Introduction
Pattern Recognition
Top-down Processing & Pattern Recognition
Face Perception
Attention
Divided attention
Selective attention
Theories of attention
2. 2 Perception Process that uses our previous knowledge to gather and interpret the stimuli that our senses register
3. 3 Pattern Recognition The identification of a complex arrangement of sensory stimuli
4. 4 Patterns
5. 5 Glory may be fleeting
6. 6 The Letter Z
7. 7 Theories of Pattern Recognition Template Matching Theory
Prototype Models
Distinctive Features Model
Recognition by Components Model
8. 8 Template Matching Theory Compare a new stimulus (e.g. T or 5) to a set of specific patterns stored in memory
Stored pattern most closely matching stimulus identifies it.
To work must be single match
Used in machine recognition
9. 9 Examples of Template Matching Attempts
10. 10 Used in machine recognition
11. 11 Problems for Template Matching Inefficient - large # of stored patterns required
Extremely inflexible
Works only for isolated letters and simple objects
12. 12 Prototype Theories Store abstract, idealized patterns (or prototypes) in memory
Summary - some aspects of stimulus stored but not others
Matches need not be exact
13. 13 Forming Prototypes Faces--Faces Animated Version
14. 14 Forming Prototypes of Faces
15. 15 Prototypes Family resemblances (e.g. birds, faces, etc.)
Evidence supporting prototypes
Problems - Vague; not a well-specified theory of pattern recognition
16. 16 Distinctive Features Models Comparison of stimulus features to a stored list of features
Distinctive features differentiate one pattern from another
Can discriminate stimuli on the basis of a small # of characteristics features
Assumption: feature identification possible
17. 17 Distinctive Features Models: Evidence Consistent with physiological research
Psychological Evidence
Gibson 1969
Neisser 1964
Waltz 1975
Pritchard 1961
18. 18 Visual Cortex Cell Response
19. 19 Gibson--Distinctive Features
20. 20 Letter Scanning Example
21. 21 Letter Detection Task
22. 22 How a Distinctive Features Model Might Work:
23. 23 Distinctive Features Theory must specify how the features are combined/joined
These models deal most easily with fairly simple stimuli -- e.g. letters
Shapes in nature more complex -- e.g. dog, human, car, telephone, etc
What would the features here be?
24. 24 Recognition by Components Model Irving Biederman (1987, 1990)
Given view of object can be represented as arrangement of basic 3-D shapes (geons)
Geons = derived features or higher level features
In general 3 geons usually sufficient to identify an object
25. 25 Examples of Geons
26. 26 Status of Recognition by Components Theory Distinctive features theory for 3-D object recognition
Some research consistent with the model; some not
27. 27 Recognition by Components Pro Biederman found that obscuring vertices impairs objects recognition while obscuring other parts of objects has a lesser effect.
28. 28 Support for Biederman
29. 29 Summary Distinctive Features approach currently strongest theory
Perhaps all 3 approaches (distinctive features, prototypes, recognition by components) are correct
Regardless, pattern recognition is too rapid and efficient to be completely explained by these models
30. 30 Two types of Processing Bottom-up or data-driven processing
Top-down or conceptually driven processing
Theme 5 -- most tasks involve bottom-up and top-down processing
31. 31 Thought Experiment Assume each letter 5 feature detections involved
Page of text approximately 250-300 words of 5 letters per word on average
Each page: 5 x 5 x 250-300 = 6250 - 7500 feature detections
Typical reader 250 words/min reading
6250/60 secs =100 feature detections per second
32. 32 Ambiguous Stimulus -The Man Ran
33. 33 Ambiguous Stimulus - The Cat in the Hat
34. 34 Fido is Drunk
35. 35 Reversible Figure and Ground
36. 36 Word Superiority Effect We can identify a single letter more rapidly and more accurately when it appears in a word than when it appears in a non-word.
37. 37 Word Superiority- Non-word Trial
38. 38 Word Superiority: Word Trial
39. 39 Single Letter K vs K in a word
40. 40 Word Superiority: Single Letter Trial
41. 41 Word Superiority: Word Trial
42. 42 Altered Sentences in Warren and Warren (1970)
43. 43 The Effect of Varying Sentence Frame Context on Interpreting an Ambiguous Stimulus The __________ raised (________) to supplement his income.
44. 44 The Influence of Stimulus Features & Sentence Context on Word Identification
45. 45 Attention
46. 46 Definitions of Attention Concentration of mental resources
Allocation of mental resources
47. 47 Divided Attention
48. 48 Reinitz & Colleagues (1974)
49. 49 Proportion of Responses that were old for Each of Two Study Conditions and Two Test Conditions (Reinitz & Colleagues, 1994).
50. 50 Divided Attention & Practice Hirst, et. al. 1980
Spelke, 1976
51. 51 Upset
Hotel
Judge
Employment
Map
Indulge
Pencil
Problem
Key
Terrible
52. 52 Selective Attention
53. 53 Selective Attention (Dichotic Listening Task) Shadowing
Irrelevant Channel
Cocktail Party Effect - Morray (1959)
Wood and Cowan (1995)
Treisman (1960)
54. 54 Dichotic Listening Task
55. 55 Cocktail Effect
56. 56 Treismans Shadowing Study
57. 57 Stroop Effect
58. 58 Filter Models of Attention
59. 59 Capacity Model of Attention
60. 60 Diagnostic Criteria for Automatic Processes
61. 61 Cerebral Cortex & Attention
