Myers’ PSYCHOLOGY

1. Myers’ PSYCHOLOGY Chapter 5 Sensation

2. Sensation and Perception • Sensation • a process by which our sensory receptors and nervous system receive and interpret stimulus energy • After receiving sensory information we must process it and this is perception • Perception • a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events • Sensation and perception blend into one continuous process

3. Sensation • Bottom-Up Processing • analysis that begins with the sense receptors and works up to the brain’s integration of sensory information • Detects lines, angles, and colors • Top-Down Processing • information processing guided by higher-level mental processes • as when we construct perceptions drawing on our experience and expectations • Information not form our senses, knowledge based • Interpretation

4. The Forest Has Eyes • Our sensory and perceptual processes work together to help us sort out complex processes • Bottom-up is the colors, lines, angles of the horses, rider and sourroundings • Top-down is the title of the painting and what will give the painting meaning

5. Sensation and Perception Cycle

6. Thresholds • We live in a world on constant stimuli • What do we notice and not notice? • What do we feel and not feel? • What do we sense and perceive? • Psychophysics if the study of how physical energy relates to our psychological experience • What stimuli can we detect? • At what intensity? • How sensitive are we to changing stimulation

7. Psychophysics • Psychophysics • study of the relationship between physical characteristics of stimuli and our psychological experience of them • Light- brightness • Sound- volume • Pressure- weight • Taste- sweetness

8. Sensation- Thresholds • Absolute Threshold • What we are super-sensitive too, even if the stimuli is faint • Eyelash on our face is one example • Absolute threshold is the minimum stimulation needed to detect a particular stimulus 50% of the time

9. Signal Detection Theory • Signal Detection Theory • Detecting a weak stimuli depends on the signal’s strength but also on a psychological state • predicts how and when we detect a weak stimulus signal • Measured as ratio of “hits” to “false alarms” • Why do people respond differently to same stimuli • Why does same person’s reactions vary by circumstances? • Why parents hear the slightest sound fro their baby, but miss louder sounds from other sources • Detection depends partly on person’s • experience • expectations • motivation • level of fatigue

10. Subliminal! • We have all heard of this • Subliminal messages can be both visual and auditory • Subliminal means stimuli below our threshold that we unconsciously detect and perceive • Remember that absolute threshold is 50% of the time – so yes we can be and are stimulated by things below that threshold • Can we feel what we do not know and cannot describe? • Can we be manipulated using this? • Psychologists say NO! • When it appears that they do is it placebo effect?

11. 100 Percentage of correct detections 75 50 Subliminal stimuli 25 0 Low Absolute threshold Medium Intensity of stimulus Sensation- Thresholds • Subliminal • When stimuli are below one’s absolute threshold for conscious awareness

12. Sensation - Thresholds • Difference Threshold (aka JND – just noticeable difference) • minimum difference between two stimuli required for detection 50% of the time • Increases with the magnitude of the stimulus • Weber’s Law- to be perceived as different, two stimuli must differ by a constant minimum percentage • Stimuli must differ by a constant proportion not amount to be noticed • light intensity- 8% difference • weight- 2% difference • tone frequency- 0.3% difference

13. Sensory Adaptation • Diminished sensitivity as a consequence of constant stimulation • Example – you walk into a house and it smells, but an hour later you no longer notice the smell. • You get used to it – you adapt • Diminishing sensitivity to unchanging stimulus

14. End Day 1

15. Day 2 – Backmasking and Subliminal Clips and Discussion • Play several clips on subliminal messages and backmasking • Response: Students are to write a 2 paragraph response analyzing what they saw today (combined with Internet Research) and explain if subliminal and backmasking work.

16. Subliminal Commercials

17. End Day 2

18. Vision • Amazing – how does light become images? • Transduction • conversion of one form of energy to another • Stimulus energy becomes neural messages • Stimulus input is light energy • Not color that strikes the eyes, but electromagnetic energy that our visual system perceives as color • We se only a mall part of the color spectrum • 2 parts of light help our sensory experience: • 1. Wavelength -the distance from the peak of one wave to the peak of the next • Determines hue (color we experience) • 2. Intensity – Amount of energy in the light waves • Influences brightness

19. Great amplitude (bright colors, loud sounds) Short wavelength=high frequency (bluish colors, high-pitched sounds) Long wavelength=low frequency (reddish colors, low-pitched sounds) Small amplitude (dull colors, soft sounds) Vision- Physical Properties of Waves

20. The Eye • Light enters the eye through the cornea • Light bends to provide focus • Light then passes through the pupil • Pupil is an adjustable opening in the center of the eye • Pupil is regulated by the iris • Iris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening • Adjusts light intake by dilating/constricting in response to intensity or even inner emotions • Behind the pupil is the lens

21. The Eye Continued • Lens focuses the incoming rays into an image on the eye’s light sensitive back surface • Does this through the process of accommodation – changing the curvature • Retina contains the receptor rods and cones and layers of neurons that process the visual information • Rods – detect black, white and grey/peripheral and twilight vision • Cones – function in daylight and well-lit conditions/fine detail/color sensations • Fovea is the retina’s central area of focus add where cones cluster around • Fovea has cones but no rods

22. Vision

24. Vision • Acuity – sharpness of vision • Can be changed by slight variations in the shape of the eye • Nearsightedness • Light rays from distant objects focus in the front of the retina • Condition in which nearby objects are seen more clearly than distant objects • Farsightedness • The image of near objects is focused behind retina • Condition in which faraway objects are seen more clearly than near objects

25. Vision • Normal Nearsighted Farsighted Vision Vision Vision

26. Retina’s Reaction to Light • Optic nerve- nerve that carries neural impulses from the eye to the brain • Blind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there • Fovea- central point in the retina, around which the eye’s cones cluster

28. Receptors in the Human Eye Cones Rods Number 6 million 120 million Location in retina Center Periphery Sensitivity in dim light Low High Color sensitive? Yes No Vision- Receptors

29. Pathways from the Eyes to the Visual Cortex

30. Day 4 – Vision in more detail • KQLW Chart • Complete 1st 2 columns • What I already know/learned • Questions I have still • Watch videos (also on website for class) • G:\Eye\030 How Eyes Work - An Introduction.mp4 • Start at 1:00 into the video • G:\Eye\032 Visual Processing in the Retina.mp4 • Start at 4:00 minutes into video • Complete column 3 • What I learned today • KQLW Chart • Complete column 4 • What I still want to learn

31. Start Day 5

32. Visual Information Processing • Visual information goes from the retina in the eye to the thalamus then to the brain’s visual cortex in the occipital lobe • 130 million rods and cones in the retina • Transmitted by the ganglion cells • Ganglions’ axons make up the optic nerve • Retinal cells are VERY sensitive • Can misfire • Even pressure can trigger misfires • Brain interprets the misfires as light

33. Feature Detection • Ganglion cells send signals to the visual cortex • Feature detector neurons respond to a scene’s specific features • Edges, lines, angles and movements • Visual cortex passes information to other areas of the cortex that respond to more complex patterns

35. “Vast Visual Encyclopedia” • Cells that are distributed throughout the brain • Respond to one stimulus but not another • Called supercells • Fire only when cues trigger them too • Ex: A goalie blocking a shot when they see the ball or puck coming or anticipate the direction it might come from

36. How the Brain Perceives • Perception combines sensory input with assumptions and expectations • If you stare at the Necker cube, it changes every few seconds • This demonstrates that perception is shifting • Brain constructs varying perceptions

37. Parallel Processing • Our brains process several things at once • Divides visual scene into dimensions • Color, depth, movement, and form • Our perceptions are based on integration of all from all the processing that happened simultaneously • Different areas of the brain process each part of the visual scene • Damage one area and certain parts of vision do not work • i.e. pouring a drink into a class – appears “frozen” – can’t see movement

38. Parallel Processing…

39. Summary of Processing of Visual Information

40. Color Vision • Light rays are NOT colored • Color is in our brains – not in the object we see • The brain manufactures color • Theory is that any color can be created by combining light waves of 3 colors • Red, green, and blue • Retina only has 3 color receptors

41. Color-Deficient Vision • People who suffer red-green blindness have trouble perceiving the number within the design • They have only 2 color receptors

42. Opponent-Process Theory After leaving receptor cells, visual info is analyzed in terms of if the opponent colors Neurons are turned on and off by certain colors “ON” “OFF” redgreen greenred blueyellow yellowblue black white white black

43. Opponent Process- Afterimage Effect • We get tired of our green response by staring at green • So – when we stare at the white (which contains all colors), we see only the red part of the red-green pairing

44. Color Constancy • Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object • In English – we see common objects as the same color even though the wavelengths may actually change.

45. End Day 5

46. Audition • Audition • the sense of hearing • Frequency • the number of complete wavelengths that pass a point in a given time • Pitch • a tone’s highness or lowness • depends on frequency

47. The Intensity of Some Common Sounds

49. Audition- The Ear • Middle Ear • chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window • Inner Ear • innermost part of the ear, contining the cochlea, semicurcular canals, and vestibular sacs • Cochlea • coiled, bony, fluid-filled tube in the inner ear through which

50. Audition • Place Theory • the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated • Frequency Theory • the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch