1. Hallucination as a Response to the Ecological Approach to Perception
Zach Montes

2. Direct vs Indirect Realism
Realism: Reality exists independently from our minds
Mind-Body Problem
Indirectly perceive via mental representation
Directly perceive without it

3. Ecological Perception
Influenced by Empiricism, Gestalt Psychology
Designed theory based on interaction with environment
Focused on Visual Perception
Affordances: actions that objects allow you to take
James J Gibson

4. How It Explains Hallucinations
Integrates physics and light dynamics
Explains optical illusions very well
Denies the existence of hallucinations
Working with a lack of physical evidence

5. My Argument
Using current techniques and technology, we now have neurological evidence linked to the existence of hallucinations
If perception exists without mind-independent stimuli, hallucinations are internally generated and understood as mental representations

6. What is a Hallucination
“A strictly sensational form of consciousness, as good and true a sensation as there were a real object there. The object happens not to be there, that is all.” William James, 1890

7. Types of Hallucinations
There is no coherent taxonomy of hallucinations
Visual Hallucinations
Simple and Complex Hallucinations
Meta-awareness, cognizant there is no external stimulus

8. Charles Bonnet Syndrome
Failing eyesight or non-congenitally blind
Patients are mentally healthy
Lack of input leads to spontaneous release of neurotransmitters

9. Sensory Deprivation Total visual deprivation
Hallucinations include faces, people, integrated scenes of animals in landscapes
Occipital and Ventral pathways involved

10. Migraine Hallucinations
Neurons are initially hyperexcitable, followed by cortical spreading depression
Evidence suggesting autonomous pattern formation in visual cortex
Bayesian theory and top-down control

11. Back to Gibson’s Approach
Even though exact pathways are not known, hallucinations do occur
Perception without mind-independent objects
People who hallucinate are perceiving mental representations

12. However, wrong ≠ unhelpful
Gibson’s work about optic flow
Contemporary research in Artificial Intelligence
Development of theory in which the observer and environment form an inseparable system

13. Future Directions Continued research on hallucinations
Development of new perceptual theories leads to advances in technology in addition to academic pursuits
Integration of direct and indirect perception in perceptual theories

14. References
Adolph, K., & Kretch, K. (2015). Gibson's theory of perceptual learning. Wrigh, J.D. (Ed.), International Encyclopedia of the Social & Behavioral Sciences. 127–134. doi: /B
Billock, V. A., & Tsou, B. H. (2012). Elementary visual hallucinations and their relationships to neural pattern-forming mechanisms. Psychological Bulletin, 138(4), doi: /a
Collerton, D., Mosimann, U. P., & Perry, E. K. (2015). The neuroscience of visual hallucinations. Chichester, West Sussex, UK: Wiley Blackwell.
Ffytche, D. H. (2005). Visual hallucinations and the charles bonnet syndrome. Current Psychiatry Reports, 7(3), doi: /s

15. References
Fish, W. (2004). The Direct/Indirect Distinction in Contemporary Philosophy of Perception. Essays in Philosophy, 5(1).
Gibson, J. J. (1979). The Theory of Affordances. In The Ecological Approach to Visual Perception, New York, NY: Taylor & Francis Group.
Guberman, S., Maximov, V. V., & Pashintsev, A. (2012). Gestalt and image understanding. Gestalt Theory. 34(2)
James, W. (1890). The Perception of ‘Things.’ The Principles of Psychology (pp. 115). doi: /
Jenkins, H. S. (2008). Gibson’s “Affordances”: Evolution of a Pivotal Concept. Journal of Scientific Psychology, December,
Käufer, S., & Chemero, A. (2015). Phenomenology: An Introduction. Cambridge: Polity.

16. Thank you