1. The Gestalt theory of illusions
GCSE Psychology
The Gestalt theory of illusions

2. Learning objectives To learn abut the Gestalt theory of illusions
To identify the strengths and weaknesses of this theory
To learn about Gregory’s perspective theory of illusions
To learn how to evaluate Gregory’s theory.

3. What type of illusions are these?
Illusions recap
Ponzo illusion
Muller Lyer illusion
Hering illusions
What type of illusions are these?
DISTORTIONS

4. What about these?
Kanizsa Triangle
FICTIONS

5. And these?
Rubin’s Vase
Leeepers Lady
AMBIGUOUS FIGURES

6. Gestalt theory of illusions
Gestalt theory could explain these illusions by....

7. DISTORTIONS Can only explain the distortion Muller-Lyer!!
When we perceive the figure as a whole, pints / fins as well, we tend to ‘add’ the fins to the straight line perceiving it as a whole rather than its separate parts. So we are stretching the line out.
Can only explain the distortion Muller-Lyer!!
Ponzo illusion
Muller Lyer illusion
Hering illusions

8. What about these? FICTIONS
Kanizas triangle – according to the law of closure, we should make out a whole even though there are parts missing....we should make out a 6 pointed star but we don’t – we see 2 triangles.
Kanizsa Triangle
Explains fictions well ~ closure law but for some there is a problem...
Seems to use different explanations at different times
FICTIONS

9. AMBIGUOUS FIGURES
Perception has to be organised differently to see the different images due to the whole being made up of the same parts meaning they can not be seen at the same time 
Tells us about ambiguous figs well ~ using figure-ground law

10. Task...
Consider the strengths and weaknesses of Gestalt theory.

11. Gestalt theory of illusions
You should now produce a booklet or poster to explain the Gestalt theory of illusions.
Use the internet to help you also but stick to the following points:
Explaining fictions, which do we recognise first?,
explaining distortions
explaining ambiguous