1. Ganglion cells project to the brain via the optic nerve information is projected to contralateral cortex! Visual Pathways

2. the retina is mapped onto primary visual cortex called a retinotopic or spatiotopic map Visual Pathways Stimulus Cortical Activity

3. signals are separated according to the type of information Visual Pathways Dorsal “Where” Pathway: Motion and Location Ventral “What” Pathway: Color and Form Primary Visual Cortex (V1)

4. Seeing

5. Seeing is the process of converting electromagnetic radiation into a conscious mental event

6. Seeing visual system faces many challenges –too much information –too little information –conflicting information –ambiguous information

7. Seeing too much information

8. Seeing too little information

9. Seeing Conflicting Information

10. Seeing Ambiguous information

11. Seeing We will consider two aspects of vision to explore how the brain overcomes these challenges: –Seeing depth –Seeing in color

12. Seeing Depth What’s the big problem with seeing depth ?

13. Seeing Depth The world is 3D, the retina is 2D !

14. Depth Cues Four categories: 1. Pictorial 2. Physiological 3. Motion 4. Stereoscopic

15. Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth

16. Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth  Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence

17. Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth  Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence  Motion Depth Cues: foreground and background move in opposite directions

18. Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth  Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence  Motion Depth Cues: foreground and background move in opposite directions  Stereoscopic Depth Cues: disparity between two retinal images indicates distance

19. Pictorial Depth Cues – Occlusion

20. Pictorial Depth Cues – Occlusion

21. Pictorial Depth Cues – Shadows and Shading

22. Pictorial Depth Cues – Shadows and Shading

23. Pictorial Depth Cues – Shadows and Shading: visual system assumes light from above

24. Pictorial Depth Cues – Shadows and Shading: visual system assumes light from above

25. Pictorial Depth Cues – Shadows and Shading

26. Pictorial Depth Cues – Shadows and Shading

27. Pictorial Depth Cues – Retinal image size –far objects smaller than near objects

28. Retinal image size –problem: big far things same as close small things –“solved” by size constancy: Perceived size is adjusted according to perceived distance (based on other cues) –forms the basis for several visual illusions Pictorial Depth Cues

29. Retinal image size Pictorial Depth Cues

30. Retinal image size Pictorial Depth Cues

31. Linear perspective Pictorial Depth Cues