1. PSYCH 2220 Perception Lecture 9

2. COLOUR Trichromacy cones, three photopigments, long wavelength, medium wavelength, short wavelength, colour matching, 'normal' need three lights, colour blindness Opponency adaptation, colour after-effect, lateral inhibition (at level of retinal ganglion cells)

3. VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions

4. VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions

5. VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions

6. VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions

7. Müller-Lyer Illusion

8. BOTTOM UP…. TOP DOWN ….

9. BOTTOM UP 1 eye movements 2 limited acuity 3 physiological confusion

10. response level cells in a hypercolumn minding their own business

11. response level when a bar comes on they give a response…

12. response level But the cells are wired together with INHIBITORY connections

13. response level so highly active cells inhibit their neighbours the most

14. response level which releases the higher-firing cells from inhibition and makes them fire more, bringing out the signal better

15. response level Now we add some other lines..

16. response level Which activate the cells tuned to those orientations…

17. response level Which pulls down the response of the vertically tuned cell

18. A physiological confusion explanation for the Müller-Lyer

19. BOTTOM UP 1 eye movements 2 limited acuity 3 physiological confusion TOP DOWN 1 empathy 2 “good figure” 3 perspective

22. EMMERT’s LAW If retinal image stays the same then perceived size will depend on distance small thing close big thing far

30. The Thatcher Illusion

32. Do we need to LEARN to see?

34. EMPIRICIST (all knowledge comes from experience) NATIVIST (knowledge is ‘a priori’; you are born with it)

35. 1 Animal behaviour 2 Blind people recovering their sight 3 Babies’ visual development 4 Adaptation experiments 5 Controlled rearing experiments EVIDENCE

36. 1 animal behaviour

37. Molyneux’s question: “could a man born blind distinguish a sphere and a cube by sight alone?” 2 blind people recovering sight

42. 3 child development, Fant’z Experiment

46. 4 adaptation

48. 5 controlled rearing

49. Blakemore video about development

50. Animal behavour Blind people recovering their sight Babies’ visual development Adaptation experiments Controlled rearing experiments EVIDENCE ……………………. Nativist … Empiricist & nativist …………. Empiricist & nativist …………… Empiricist ……….. Empiricist