1. Visual Illusions

2. Definition Illusions occur when what we see does not correspond to what is physically present in the world

3. Brightness After Effect Please Stare for a while

4. Colour After Effect + Please Stare for a while

6. Negative Colour After Images +

7. Motion Contrast

8. The Zöllner Illusion (Orientation Contrast)

10. Object size is inferred from perceived distance and retinal image size If 2 objects have the same retinal image size (i.e., are the same real size), the object appearing further away is seen as larger Size-Distance Relationship

12. The Ponzo Illusion Gregory’s theory The visual system makes hypotheses about distance to objects based on evidence in the image. Interpretation of size follows.

13. Müller-Lyer Illusion

14. 0510 Objectively equal in separation, perceptually different 0510

15. Müller-Lyer Illusion Perceptually equal in separation, objectively 30% different 051015

16. Perspective cues set up false interpretations of distance Müller-Lyer Illusion

17. Ames Room

18. Ames room Ames room sets up false distance cues Objects that are different distances appear the same distance

19. Reversible Figure and Ground

20. Necker cube Look at the red dot… It can be either on a near corner or a far corner

21. Ambiguous figures Old woman looking down/young woman looking away

22. Ambiguous figures

23. Rabbit

24. Ambiguous figures Duck

26. How many dolphins?

29. Penrose Triangle

30. Escher’s prints The brain cannot compute 3-D structure from all parts at once, each part looks plausible in isolation

31. Escher’s prints

33. The Thatcher Illusion

34. This is the same stimuli but 1 looks more strange than other