Higher Visual Processing

Visual Cortex (area V1(& V2)):

Hubel and Wiesel (1959)


Types of Cortical Cells:

1. Simple Cortical Cells:












2. Complex Cortical Cells:










3. End-Stopped Cells: (a.k.a. feature detectors)










Organization of Cortical Cells:




1. Location Columns:









2. Orientation Columns:







3. Ocular Dominance Columns:






4. Hypercolumns -





Extrastriate Cortex (areas beyond the primary visual cortex(V1) -- V3, V4, & V5)


Different processing pathways for different pieces of information.

A. Form channel (V3):










e.g. prosopagnosia--



B. Color channel (V4):







C. Motion channel (V5):












Object Perception

Gestalt Approach to Object Perception: (gestalt means "whole" or "shape")



Figure and Ground:


e.g. ball resting on a grassy field

ball =

grass =






Factors that determine what is seen as figure and ground:




Oyama (1960) -


= same size= smaller size



















Examples of Ambiguous Figure/Ground:

e.g. Escher





Illusory Contours:










More complex illusory contours -








e.g. necker cube figure




Gestalt Principles of Organization:



1. Proximity:





2. Similarity:


3. Good Continuation:



4. Common Fate: (Law of common motion)



5. Closure:



6. Pragnanz:








Modern Gestalt Principles:

7. Common Regions:



8. Element Connectedness:



9. Synchrony:


e.g. flashes of light