Perception and Pattern
What types of information do we use to
perceive the world correctly?
What are the major theories about how we
What are the strengths and weaknesses of
Types of Perceptual Processes
• Bottom-up - work up from sensory info.
• Top-down - apply knowledge and experience
Chess masters remember chess board
patterns better than novices (Chase &
Easier to recognize objects in context
Template Matching Theory
Recognize patterns by matching stimulus to
Works in price scanners
Problems with Template Matching
• Differences in orientation
• Differences in size
• Differences in form
Identify simple features of patterns
Combine features into complex patterns
Hubel & Wiesel (1965) found feature detector
neurons in cats
Visual search: easier to find target when it
doesn’t share features with the background
Find the Z
Treisman’s Feature Analysis
Preattentive Stage: detect visual features
Focused Attention Stage: combine features
Problems with Feature Analysis
Two different patterns can have
the same features
Patterns may not have any
features that are required
Law of Pragnanz
Prototype Matching Theory
Prototype - “best” or “typical”
representation of a pattern
Stimulus is compared to prototypes
Uncertainty in pattern recognition
Pseudomemory (Solso & McCarthy,1981)
Study These Faces...
Which Did You See?
A is the prototype; it was not seen.
B was not seen.
C was one of the original faces.
What problems must the brain solve to
Inverse projection problem
How does the brain solve these problems?
Top-down and bottom-up
Built-in brain organization