The document discusses the construction of visual reality from several perspectives. It begins with a brief review of the contents of a book on hallucinations. It then discusses visual illusions, explaining that they are incorrect perceptions experienced by most people in specific contexts. The document proposes that vision involves construction rather than passively receiving information, and evolution favors perceptions that guide adaptive behavior over strictly veridical perceptions. It provides examples of biological visual systems that construct reality for utility rather than truth. Finally, it proposes a new theory defining illusions as common non-adaptive perceptions and hallucinations as rare context-less non-adaptive perceptions.

1. The Construction Of
Visual Reality
Hamed Abdi
PhD Student in Computational Cognitive Science
Institute for Cognitive & Brain Science (ICBS)

2. Framework
 A Brief Review on Book
 Illusions: What and Why
 Vision as Construction
 Perceptual Evolution
 Interface Theory of Perception
 Biological Examples
 Hallucinations

3. A Brief Review on Book
Contents:
Part I: Conceptual Issues
 A Network Model of Hallucinations
Part II: Hallucinatory Phenomena
 Phantom Body, Phantom Self: A Phenomenology of “Body
Hallucinations”
 Djinns
Part III: Research
 Functional Neuroimaging of Hallucinations
 Neurophysiological Research: EEG and MEG
Part IV: Treatment

4. Illusions: What and Why
Wagon wheel effect

5. Illusions: What and Why
 Illusions vs. Hallucinations
 Incorrect perception
 Most/Few people
 Specific/Absence Stimulus

6. Illusions: What and Why
 Why our perceptions should be fallible?

7. Illusions: What and Why
Standard view More accurate perceptions are more fit
What you see is what you get
Struggle for survival:
 Perception the more truly structure of the world
 Constructive process to guide adaptive behavior

8. Vision as Construction
The Camera Theory Of Vision
BUT
 Billions of neurons in visual cortex?!!!
 Computational power is not necessary
to take a picture.

9. Vision as Construction
The visual system constructs our visual worlds because it must.
but why?
From Photon to Visual Cortex
From 2D to 3D

10. Vision as Construction
Marr's Visual Representational Framework

11. Vision as Construction
Illusion and construction are inextricably linked

12. Vision as Construction
A example of visual construction

13. Perceptual Evolution
Truth and utility are distinct concepts
u :W  O  R
World Organism
Reality/Truth Utility
benthic fish

14. Perceptual Evolution
Mathematical Theory of Evolution
Evolutionary Game Theory
Natural Selection law:
True Perception Swift Extinction
Perceptual information does not come FREE !!!

15. Interface Theory of Perception
Windows Desktop Metaphor
Desktop Time-Space
Icons Objects
Hide the complexities of the truth
Adaptive Behavior

16. Interface Theory of Perception
Inexistence Drag to trashcan!!!
Conventionalism
Idealism
Symbolism

17. Biological Examples
Dragonfly:
Polarization of light in water and
asphalt road
Ecological traps
Mimicry
Camouflage

18. A New Theory of Illusions and Hallucinations
 An illusion is a perception, experienced by
most people in a specific context, that is not
an adaptive guide to behavior.
• A hallucination is a perception experienced
by few people that occurs in the absence of
an appropriate context and that is not an
adaptive guide to behavior.
Correct Perception
Adaptive Behaviors GABAergic System

19. Interpretation

20. Thank for your attention
Any Question?