2. Kanizsa triangle

3. Gregory’s Indirect Theory (1974)
Top-down theory of perception

4. Gregory’s indirect theory
Perception process of construction
Based on:
Sensory data
Previous knowledge
Hypothesis about what is out there

5. Hypothesis testing
Necker cube

6. Hypothesis testing: Rubin’s vase

7. Hypothesis testing

8. Previous knowledge Rotating masks:

9. Previous knowledge

10. Previous knowledge
What shape is this?

11. Muller-Lyer Illusion
Which one is longer?

12. Depth cues

15. Auditory Expectations
Led Zeppelin – Stairway to Heaven
Lyrics: “Oh here’s to my sweet Satan. The one whose little path would make me sad, whose power is Satan. He’ll give those with him 666; there was a little tool shed where he made us suffer, sad Satan.”

16. Palmer (1975)