PERCEIVING SCENES. Visual Perception

Transcription

1 PERCEIVING SCENES Visual Perception

2 Occlusion Face it in everyday life We can do a pretty good job in the face of occlusion Need to complete parts of the objects we cannot see Slide 2

3 Visual Completion Perceive partly occluded surface as complete Slide 3

4 Visual Completion Multiple possible perception Only one is dominant How might it happen? Figural familiarity Figural similarity Ecological Constraint Slide 4

5 Figural Familiarity Slide 5

6 Cannot Explain We can complete novel shapes Theory still holds Slide 6

7 Figural Simplicity Complete as the simplest figures What is simple? Is simplicity number of sides or number of axes of symmetry? Slide 7

8 Ecological Constraints Based on ecological evidence of occluded contours E.g. T- Junction Slide 8

9 Relatibility Theory Edge discontinuities are necessary Relatable Discontinuities Intersect at 90 degree Smoothly Connected Slide 9

10 Relatibility Theory Edge discontinuities are necessary Relatable Discontinuities Intersect at 90 degree Smoothly Connected Form a enclosed Area Infer position in depth Slide 10

11 Let us take an example Can you almost perceive depth? Slide 11

12 Illusory Contours Come with Visual Completion Enclosed space is important Slide 12

13 Alternative Perception Slide 13

14 Alternative Perception Slide 14

15 Perceived Translucency Perceived as being viewed through a closer translucent object Slide 15

16 Translucency Slide 16

17 Multistability More than one perception Spontaneously alternate between more than one perception Necker Cube Slide 17

18 Network Model Slide 18

19 Why only one interpretation at a time? Slide 19

20 Why does alteration happen? Neural Fatigue Theory Slide 20

21 Why does alteration happen? Neural Fatigue Theory Not the only one Role of eye fixation or instructions Slide 21

22 Perceivable Properties Shape Orientation Size Position Slide 22

23 Shape Constancy Perceive objects to be of same shape despite being viewed from different viewpoints Slide 23

24 Size and Shape is related Slide 24

25 2D objects Slide 25

26 3D objects Slide 26

27 3D objects Slide 27

28 Shape Illusions Cicle/Ellipse Ponzo Ames Room Slide 28

29 Orientation Constancy Objects don t tilt when our heads tilt Slide 29

30 Proprioceptive System Slide 30

31 Tilted Room Illusion K4-AI Slide 31

32 Zollner Illusion Slide 32

33 Zollner Illusion Slide 33

34 How much can we adapt? Slide 34

35 How much can we adapt? Slide 35

36 How much can we adapt? Slide 36

37 Retinal Un-Inversion Experiment Slide 37

38 Parts Perceive shape, size and orientation by parts Linguistic and phenomenological evidence Refer by parts: Palm, toe, shin, ankle All over the world in all cultures Slide 38

39 Which comes first? Whole or parts? Slide 39

40 Global Precedence Global advantage Responds faster to global letters Global to local interference Inconsistency slows local letter identification Lack of local to global interference Inconsistency does not slow down the global letter identification Processed in different halves of brain Slide 40

41 In two different parts of brain Preferences : Local on left, global on right Slide 41