Chapter 6 Sensation & Perception

1. Chapter 6Sensation & Perception

3. Sensation The raw data of experience Perception Process of creating meaningful patterns from raw sensory information Sensation vs. Perception • 2 can be joined for practical use • Hearing aids • Robots • Flight simulators

4. 5 Senses Sight Touch Smell Taste Hearing Other senses Heat Pressure Pain Balance Movement Sensing

5. chapter 6 Riddle of separate sensations Sense receptors • Specialized cells that convert physical energy into electrical energy that can be transmitted an impulses to the brain • Signals received by the sense organs stimulate different nerve pathways leading to different areas of the brain. • Ex: Rub your eyes results in visual experience Synesthesia • A rare condition in which stimulation of one sense also evokes another • Ex: See color purple and claim it smells like a rose

6. chapter 6 Absolute threshold • The smallest quantity of physical energy that can be reliably detected by an observer 50% of the time

7. chapter 6 Absolute thresholds Vision Candle flame from 30 miles on a clear night Hearing Tick of a watch from 20 feet in total quiet Smell One drop of perfume in a 3-room apartment Touch Wing of a bee on the cheek, dropped from 1 cm Taste One teaspoon of sugar in 2 gallons of water

9. chapter 6 Difference threshold • The smallest difference in stimulation that can be reliably detected by an observer when two stimuli are compared • Also called the Just Noticeable Difference (JND)

10. Sensory Process Real stimulus causes perception Example: phone rings and you hear it Decision Process No stimulus present, mental error Example: Waiting for phone call and in shower, think heard phone ring chapter 6 Signal-detection theory

11. chapter 6 Sensory adaptation and deprivation Adaptation • The reduction or disappearance of sensory responsiveness when stimulation is unchanging or repetitious • Prevents us from having to respond continuously to unimportant information • Example: You cannot smell your perfume / cologne a few minutes after spraying Deprivation • The absence of normal levels of sensory stimulation

12. chapter 6 Sensory overload • Over-stimulation of the senses • Can use selective attention to reduce sensory overload • Selective attention: the focusing of attention on selected aspects of the environment and the blocking out of others (cocktail party phenomenon)

13. chapter 6 What we see Hue • Color Names related to the wavelength of light (ROYGBIV) Brightness • Amount of light emitted from or reflected by an object Saturation • Complexity of light waves

14. chapter 6 The Parts of the Eye Cornea - Protects eye and bends light toward lens Iris - Controls amount of light into eye Pupil - Opening through which light reaches the retina Lens - Focuses on objects by changing shape Retina - Area where light is focused onto Blind Spot - Area of retina where there are no receptors

15. Parts of the Eye

16. Blind Spot

17. Rods Receptors that respond to light & dark 120 million per eye Used for Night vision Cones Visual receptors involved in color vision 8 million per eye Best in daylight Sharpness of vision chapter 6 Color Vision - Receptor Cells

18. chapter 6 Trichromatic theory • Eye detects 3 primary colors • Red,Blue, Green • All other colors derived by combination • Limits does not explain color blindness or after image

19. Trichromatic Spectrum

20. chapter 6 Opponent-process theory • Visual system treats pairs of colors as opposing • Red-Green • Yellow-Blue • Black-White • Only one side may fire at a time • Why cannot see reddish-green or yellowish-blue colors • Explains Afterimage and Colorblindness

21. Afterimage • The firing of cone has unused energy after viewing something steadily • Visual system wants to return to balance • Fires in opposite color

28. Color Blindness • It is inherited 8% males & 0.5% females • Monchromats - see only black & white • Dichromats - typically red / green cannot be seen

38. chapter 6 Vision is not a camera • Most processing is done in the brain • Flips the image right side up • Fills in holes from blind spot • Influenced by one’s experiences & expectations

39. chapter 6 Gestalt Principles • Brain’s organization of sensory building blocks into meaningful units and patterns. • Wertheimer, Kohler, Koffka

40. Gestalt Principles Figure- Ground • In any visual image, figures can be distinguished from the ground on which they appear

41. Gestalt Principles Proximity • Things close to one another are grouped together

42. chapter 6 Gestalt principles Closure • The brain tends to fill in gaps to perceive complete forms

43. Gestalt Principles Similarity • Things that are alike are perceived together • Continuity • Seeing continuity in lines that could be interpreted as either continuous or abruptly shifting in direction.

47. Gestalt Principles • Design 3 images in your journal • Each one must use a Gestalt principle • Figure-ground • Proximity • Closure • Similarity

48. chapter 6 Depth and distance perception Binocular cues • Visual cues that require the use of both eyes • Convergence • Turning inward of the eyes, which occurs when they focus on a nearby object • Retinal disparity • The slight difference in lateral separation between two objects as seen by the right and left eyes

49. Binocular Vision

50. Binocular Vision