1. What Gestalt principle is being used here?

2. WHAT IS AN ILLUSION? A perceptual misinterpretation of reality.
Illusions are misperceptions of real sensory stimuli.
There are more than 200 visual illusions.

3. FICTIONS When you perceive a shape that is not there
We think we see edges even though there is no boundary line

4. AFTER EFFECTS
When you look at something for a long time and then look away you see the opposite colours
WHY?
Because the receptor cells in the retina become tired if we stare at something for too long
If RED cones get tired then GREEN cones spring into action (and vice versa)
If BLUE cones get tired then YELLOW springs into action (and vice versa)

6. After-effects also work with motion too
1. Look at the cross
2. Now try and follow the green dot!

8. GLOSSARY
AMBIGUOUS FIGURE
DISTORTION ILLUSION

9. AMBIGUOUS FIGURES
Sometimes what we are looking at has more than one perspective
We can only see one image at a time
Swapping between the 2 images is hard to do – but not impossible

11. CAN YOU CHANGE DIRECTION?

12. DISTORTIONS You know what you are seeing is wrong
They only work on paper
When you can walk around it the illusion goes away
Channel 4 is advertised this way

16. What are illusions? Read pages 245-246
Briefly describe the Ames Room and explain how the illusion works
If we watch a person walk from the back right-hand corner of the Ames Room to the back left-hand corner they appear to shrink. Why?
Why is the observer’s view restricted to a monocular one?