Chapter 4: Perception

1. Chapter 4: Perception Music: “Speed of Sound” Coldplay “Suddenly I see” KT Tunstall

2. Lecture #4: Agenda • *Midterm Information* • 1. Distinction between Sensation and Perception • 2. Perceptual Organization: • a) Visual Capture • b) Form Perception • c) Depth Perception • 3. Interpretation • a) Sensory Restrictions • b) Perceptual Sets: Context & Contrast Effects • 4. ESP: Extra-Sensory Perception

3. Midterm October 19th • 2 hours in class; no lecture • 60 multiple choice (80%) • 4 short answers (20%) • To prepare: • 1) TEXT: • Read ENTIRE CHAPTERS • Concentrate on sections covered in class • To study: • Use the features in your book, e.g. concept checks, multiple choice questions, “Review of Key Points” • 2) LECTURES: • Go over your notes carefully, and try to anticipate short answer questions from the slides • 3) TUTORIALS: • Tuesday 10:30 a.m. Vari Hall 3006 • Tuesdays 2:30 p.m. Chemistry 115

4. 1. Distinction Between Sensation and Perception • Sensation: • Based on activity of the sense receptors • How physical energy is transformed into neural impulses • E.g. Light = Wavelengths ---- Hit retina---- Transformed into sight by the brain (p. 131-132)

6. 1. Sensation (cont’d) p.138

7. 1. Sensation (cont’d) • Primarily Bottom-Up processes: • i.e. from the outer world, to the senses, up to the brain

8. Bottom-up or Top-Down?

9. Example of • Top–down

10. 1. Sensation & Perception (cont’d) • Perception • How we analyze sensory information • Elaboration, transformation, interpretation of what is registered by the senses • Assignment of Meaning to sensory experiences • Top-down processes • Starts in the brain • Sometimes overrides the sensory input

11. Perception • E.g. Top-down process: • subjective contours (p. 152)

12. 1. Sensation vs. Perception p. 132

14. Reversable figure Perceptual illusion Perception:

15. The Role of Interpretation • You see the world that you have made • but you do not see yourself as the image maker. • How can you influence your perceptions? • What kind of images do you want to focus on? • What image maker will you be?

16. 2. Perceptual Organization • a) Visual Capture: • Sight has preeminence over other senses • b) Form Perception: • Gestalt Principles • Figure-ground relationship (p. 153) • Grouping Principles: • Similarity • Proximity • Closure • Continuity

17. 2. b) Grouping Principles (p. 153)

18. 2. c) Perceptual Organization: Depth Perception How do we transform 2-D retinal images into 3-D perceptions? • i) Binocular Cues: • Retinal disparity: • difference btw. 2 retinal images provides important clues to the brain • Angle of convergence: • muscular movement to focus on an object provides info. on distance

19. 2. c) Depth Perception (cont’d) • ii) Monocular Cues • Important for more distant objects • Relative Size • Linear Perspective • Texture gradient • Overlap • Relative height • Motion Parallax (p. 156)

20. 2. c) ii) Monoculors clues

21. Quick Test for Colour Blindness

22. Quick Test for Colour Blindness

23. 2. c) ii. Monocular cues (p. 180)

24. 2. c) ii. Monocular cues (cont’d)

25. 3. Interpretation • a) Sensory Restriction: • For some aspects of visual perception, experience is critical • Experiments with cats • Cataract patients • b) Perceptual Sets: • Needs, beliefs and emotions influence perceptions • Prior experience and expectations also provide a readiness to perceive in a certain way • Context effects: Immediate context influences perception (e.g. film sets) • Contrast effects • Comparitors p. 185 • E.g. student letter to parents

26. 4. ESP: Extra-Sensory Perception • Claims of ESP: • (perception without sensation) • Telepathy: mind to mind communication • Clairvoyance: perceiving remote events • Precognition: perceiving future events • Psychokinesis: moving objects with one’s mind • Skepticisms About ESP: • Parapsychologists: Study “para” normal phenomena • “After tens of thousands of experiments, there has never been discovered a reproducible ESP phenomenon, nor any individual who can convincingly demonstrate psychic ability” (Marks, 1986)

27. 5. Quiz Questions • Perceptual constancy refers to: • a. seeing life in a seamless way, like a movie • b. our perception of objects remaining stable despite the fact that sensory information changes • c. the existence of schemas that guide our perception • d. visual fields in the retina that allow our perception of the world to remain stable • e. linear perspective

28. 5. Quiz Questions (cont’d) • Someone singing “off key” would produce sound wave of a different ____ than someone singing “in tune: • a. amplitude • b. purity • c. tonal quality • d. frequency

29. 5. Quiz Questions (cont’d) • High levels of dopamine at brain synapses appear to play a role in which of the following? • a. hyperactivity • b. depression • c. high anxiety • d. Parkinson's disease • e. schizophrenia

30. Happy Reading Week! Keep breathing…. & Good luck studying!