Perceptual Processes:Visual & Auditory Recognition

Dr. Claudia J. StannyEXP 4507

Memory & Cognition

Spring 2009

Perception

• Distal stimulus• Proximal stimulus• Sensory memory

• Iconic memory• Echoic memory

Claudia J. Stanny 2

Iconic Memory

• Perceptually detailed visual memory

• Duration is very short ( .5 sec - 1 sec)

• Information stored has not been analyzed yet for meaning

• Precategorical sensory information• Content can be cued effectively based on sensory

qualities, not meaning

Echoic Memory Auditory analog to iconic memory

Precategorical auditory (sensory) information• Can cue recall of selected items based on

sensory qualities but not based on meaning

Very short duration (approximately 2 sec)

Sensory Processes & the Brain

Claudia J. Stanny 5

Gestalt Psychology: Organizing Principles in Perception

Form perceptionFigure-ground resolutionDetection of contours (subjective contours)Principles of organization

• Proximity• Similarity• Good continuation• Closure• Common fate

Claudia J. Stanny 6

Object Recognition

• Template-matching models• Feature analysis models• Recognition-by-components models

Claudia J. Stanny 7

Template-Matching Models

Claudia J. Stanny 8

Effective for pattern recognition for small sets of well-defined patterns

Template matching used today for pattern recognition of bank codes on checks

Feature Analysis Models

Claudia J. Stanny 9

Selfridge (1958) Pandemonium

Feature Analysis ModelsRelies on simpler features for

template matching

Includes a system of rules for how features are combined to create specific patterns

Draws on single-unit data for neurons responding to sensory input (e.g., work by Hubel & Wiesel, 1965, 1979, 2005)

Claudia J. Stanny 10

Recognition-by-Components Models

Similar to feature analysis models

Developed for perception of 3-dimensional objects

Biederman (1990)

Claudia J. Stanny 11

Top-Down & Bottom-Up Processing

• Bottom-up processing• Emphasis on sensory input• Raw sensory input → pattern recognition

• Top-down processing• Emphasis on concepts and expectations• Expectations and context create biases to extract

certain patterns from sensory input

Claudia J. Stanny 12

Errors in Perception

• Levin & Simons (1997, 2000)• Change blindness• Inattention blindness

Claudia J. Stanny 13

Change Blindness Demonstration

Links to VideosMagic Trickhttp://www.youtube.com/watch?v=voAntzB7EwE

Harvard: Participants signing up for an experiment

http://www.youtube.com/watch?v=mAnKvo-fPs0

Original Door Study (Levin & Simon, 1997)http://viscog.beckman.uiuc.edu/flashmovie/12.php

Recreation of Simon’s Door Experimenthttp://www.youtube.com/watch?v=p1aEqBaK3aM

Claudia J. Stanny 15

Face Recognition

Perception of faces Prosopagnosia

Claudia J. Stanny 16

Thatcher Illusion

Based on tendency to process faces holistically

When faces are viewed upside down, we might not detect alterations in component parts

When faces are viewed right side up, these changes are easily detected

17

Speech Perception

• Phoneme recognition• Detection of word boundaries• Constructive nature of speech perception• Context effects on speech recognition

• Phonemic restoration• McGurck effect

Claudia J. Stanny 18

Theories of Speech Perception

• Speech perception as a special mechanism of the brain

• Speech perception as characteristic of general perceptual mechanisms

Claudia J. Stanny 19