Perception

1. Perception • Perception - is a collection of all the processes or channels for gaining information about the world around us and our place in the world (physical location) • That is, all senses (sight, sound, touch, etc.,) • Crucial for survival and effective behavior • Is an ACTIVE process • Actively searching for info • Actively constructing internal representation Psychology 1

2. Understanding perception is harder than perceiving • Perceptual Mechanism (touch eye socket demo) • How perception occurs and how we get a representation of the world. (why we make perceptual mistakes) • Need different types of knowledge to do so • Basic Anatomy & Physiology • Psychophysics • Patterns of Stimulation (effect on Perception.) • Physiological Mechanisms underlying Perception. Psychology 1

3. Basic Anatomy & Physiology • Nervous system in general • Sensory systems in particular • Will emphasize human systems • (particularly vision and audition) Psychology 1

4. Psychophysics • . • Concerns the relationship between: Psycho – the world of EXPERIENCE Physical – the world of REALITY & • How much light? How much sound? • Intensity vs. Brightness • How well do we adapt? • What are the limits of the senses? Psychophysical Methods Psychology 1

5. Contrast & Assimilation • . Psychology 1

6. Subjective Contours • . Can you PERCEIVE a triangle? Can you CONCEIVE of a triangle? There is a difference between perception and cognition Psychology 1

7. Connections? • Different occupations with various demands fit to the content of this course • Air Traffic Controller (safe path) • Radiology (normal or abnormal) • Food Manufacturer ( Crunchy Munchy) What does all this have in common? • Psychophysics Psychology 1

8. Psychophysics • Looks at the relationships and study the relationships between the physical and perceptual world • That is, Experience and Physical reality Psychology 1

9. Measuring Perception • Detection “problem” – Is there something there. How bright before someone know it is there. • Discrimination – How do you tell a difference. Are these two different? • Scaling – Change in Physical and Change in Experience. Not quantitatively equal in change between perceptual and physical • Recognition or identification – how do you identify or recognized what you’ve seen before. Psychology 1

10. The Eye Psychology 1

11. Sclera; white membrane • Cornea; focuses light • Iris; muscles behind cornea • Pupil; opening at center of iris • Lens; focuses light • Retina; cones and rods • Pigmented Choroid; small blood vessels Psychology 1

12. Optic disk; blind spot • Optic nerve; contains ganglion cell fibers • Vitreous Humor; jelly like substance • Aqueous Humor; nourish eye • Ciliary Muscles; connects to Zonule fibers • Zonule fibers; mesh-like sac around lens • Canals of Schlemm; “drain” Psychology 1

13. Problems with the Eye • Glaucoma; blockage at Canals of Schlemm, increase in intraocular eye pressure. • Open angle – rapid onset, notice earlier, change occurs over a period of hours. 10% of Glaucoma cases. • Closed Angle – gradual onset, clogged up gradually and not easy to notice with few symptoms. 90% of Glaucoma cases. • Check up should be done past 30 years old at a regular basis. Psychology 1

14. Glaucoma cont’ • Remedy may be in the form of eye drops to balance pressure. • Laser surgery to open canals of schlemm but only if caught at the early stages. Psychology 1

15. Cross section of Retina (less than 1mm thick) “inverted retina” -all mammals. Psychology 1

16. Receptors • Rods • rod shaped • Peripheral (none in fovea) • Many rods : bipolar cells • Black and white, night/dim light • Cones • Cone shaped • Centrally located • One cone: one bipolar cell • Color • daylight Psychology 1

17. Muscle System • Intraocular • Iris & Ciliary • Extraocular • Three Pairs • Cyclotorsional • 10-20 degrees Psychology 1

18. Eye Movement • Fixation • Eyes directed at a point • Focus • Have image on the back of eye • Vergence; changes for different distances • Version • Left & Right; same direction at same time Psychology 1

19. Eye Movement cont’ • Saccadic vs. Pursuit • Saccadic • Rapid/ sudden change in refixation • 1/10 of a sec. • Pursuit • Slower and smoother • “tracking” • Requires target Psychology 1

20. Focusing on an image • Cornea & Lens • Accommodation; change focus • Only lens contributes to focusing of objects • Far object; ciliary muscles relax, lens less power, lens less curved • Near object; ciliary muscles contract, lens more power, lens more curved Psychology 1

21. Problems with clarity • Myopia • Nearsightedness; eyeball is too long, need minus lens to reduce focusing power • Hyperopia • Farsightedness; eyeball is too short, need positive lens to increase focusing power • Presbyopia • Old eye, lens hardened, lost of accommodation (reduction in range) • Bifocals & multifocals Psychology 1

22. Surgery for eye • RK; Radial Keratonomy (cut into cornea to collapse and make flatter) • PRK; Photo Refractive Keratectomy (Remove part of cornea) • LASIK; (“flap & zap”) early recovery period Psychology 1

23. Surgery for eye cont’ • Cataracts; interferes with ray of light entering into eye, glares and blurs. • Rid natural lens of eye • Replace loss power • Strong glasses or • Contact lens or • INTRAOCULAR IMPLANTS (artificial lens inserted into eye) • Astigmatism; uneven curvature of the cornea • Weighted contacts Psychology 1

24. Sensitivity Psychology 1

25. Spectral Sensitivity Curves Psychology 1

26. Dark Adaptation Psychology 1

27. Pathways of vision Psychology 1

28. Color Vision • Three sorts of necessary background • Physiological Basis • Color Mixtures • Describing color experiences Psychology 1

29. Physiological Basis • 3 Different Photopigments • Cyanolabe = blue cones • Chlorolabe = green cones • Erythrolabe = red cones Psychology 1

30. . Psychology 1

31. Psychology 1

32. Color Vision Defects can be Inherited • Problems • Sex-linked recessive (x-chrom.) • # men > # women Psychology 1

33. Color Vision Defects can be Acquired • Subject to change, progression • Aging • lenses yellow • Disease • Diabetes • Glaucoma • Medications • Antihistamines • Diuretics • Some antibiotics • Other Drugs • Alcohol • Marijuana Psychology 1

34. Psychology 1

35. Psychology 1

36. Psychology 1

37. Psychology 1

38. Psychology 1

39. Psychology 1

40. Psychology 1

41. Psychology 1

42. Psychology 1

43. Psychology 1

44. Psychology 1

45. Psychology 1

46. Psychology 1

47. Psychology 1

48. Psychology 1

49. Psychology 1

50. Psychology 1