Myers’ PSYCHOLOGY

1. Myers’ PSYCHOLOGY Sensation Taken from: James A. McCubbin, PhD Clemson University Worth Publishers

2. Sensation & Perception • Sensation • a process by which our sensory receptors and nervous system receive and represent stimulus energy • Perception • a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

3. Sensation & Perception • Bottom-Up Processing • analysis that begins with the sense receptors and works up to the brain’s integration of sensory information • Top-Down Processing • information processing guided by higher-level mental processes • as when we construct perceptions drawing on our experience and expectations

4. Prosopagnosia  Sensation  Perception a.k.a.“Face Blindness”

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

6. Sensation- Thresholds • Absolute Threshold • minimum stimulation needed to detect a particular stimulus 50% of the time 50%

7. Thresholds Do I taste it or not? When stimuli are detectable less than 50 percent of the time, they are "subliminal." Absolute threshold is the intensity at which we can detect a stimulus half the time.

8. Sensation- Thresholds Some info added from Essentials Psychology I • Difference Threshold orJust Noticeable Difference (JND) • Measures how much a stimulus must change before it becomes noticeably different • The study of difference threshold or JND led to Weber’s law

9. Sensation- Thresholds Some info added from Essentials Psychology I • Weber’s Law • to perceive as different, two stimuli must differ by a constant minimum percentage • light intensity- 8% • weight- 2% • tone frequency- 0.3% • Law indicated that the more intense the stimulus, the more the stimulus intensity must be increased before a change is noticed • i.e. if music was being played softly, a small increase in sound would be noticeable… if music were being played loudly, it would require a much greater increase in sound to perceive as different

10. Sensation- Thresholds • Sensory adaptation • diminished sensitivity as a consequence of constant stimulation

11. Vision- Stabilized Images on the Retina Sensory adaptation: Now you see it, now you don't! (a) A projector mounted on a contact lens makes the projected image move with the eye. (b) Initially the person sees the stabilized image, but soon she sees fragments fading and reappearing.

12. Sensation- Thresholds • Signal Detection Theory • predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) • detection depends partly on person’s • experience • expectations • motivation • level of fatigue

13. Vision • Transduction • conversion of one form of energy to another • in sensation, transforming of stimulus energies into neural messages

14. The spectrum of electromagnetic energy This spectrum ranges from gamma rays as short as the diameter of an atom to radio waves over a mile long. The narrow band of wavelengths visible to the human eye (shown enlarged) extends from the shorter waves of blue - violet light to the longer waves of red light.

15. 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 Intensity Wavelength

16. Vision (dominant sense) • Pupil-adjustable opening in the center of the eye • Iris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening • Lens-transparent structure behind pupil that changes shape to focus images on the retina

17. Vision • Accommodation- the process by which the eye’s lens changes shape to help focus near or far objects on the retina • Retina-the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual information

18. Liquid Vision Ciliary Muscle *Pupil* Sclera (white of eye) (Aqueous Humor) *Iris* Added from Essentials Psychology I Suspensory Ligament

19. Vision • Acuity- the sharpness of vision • Nearsightedness- condition in which nearby objects are seen more clearly than distant objects because distant objects in front of retina • Farsightedness-condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind retina

20. Vision Nearobject Normal Vision Nearsighted Vision Farsighted Vision Distant object

21. Vision Nearsighted farsighted

22. Retina’s Reaction to Light-Receptors • Rods • peripheral retina • detect black, white and gray • twilight or low light • Cones • near center of retina • fine detail and color vision • daylight or well-lit conditions

23. 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

24. Retina’s Reaction to Light From Essentials Psychology I • Horizontal Cells – retinal cells that connect rods with other rods and cones with other cones. • Appear to be responsible for the Opponent Process Theory of color vision • Amacrine Cells – large retinal neurons that connect ganglion cells laterally. The functions of most amacrine cells are unknown.

25. Amacrine Cells Horizontal Cells

26. Retina’s Reaction to Light From Essentials Psychology I • Feature detectors • Cells contained in the occipital cortex • Includes… • Simple cells (edge detectors) – respond to lines or edges • Complex cells – respond to the motion and color of objects • Hypercomplex cells – respond to an object’s orientation, movement, shape, corners, width, color, and length

27. 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

28. How the Brain Perceives As you stare at this Necker cube, providing fairly constant stimulation to your retina, your perception-and accompanying neural activity in your brain-will change every couple of seconds.

29. Visual Information Processing • Parallel Processing • Instead of step by step processing, our brains can process several things at once.

30. Visual Information Processing • Trichromatic (three color) Theory • Young and Helmholtz • three different retinal color receptors Red Green Blue

31. Visual Information Processing From Essentials Psychology I • Three attributes used to describe color: • Hue – determined by wavelength of light; color of visible light • Brightness – function of the overall intensity of all the wavelengths • Saturation – purity or richness of color

32. Visual Information Processing From Essentials Psychology I • Subtractive Color Mixing • Mixing paints and pigments • The two or more paints being mixed absorb or subtract more wavelengths of light than either one does alone • In SCM, yellow mixed with blue results in green (red / blue = purple; red / yellow = orange)

33. Visual Information Processing From Essentials Psychology I • Additive Color Mixing • Combination of beams of light • Human eye and color TV work according to ACM… mixing lights produces a color lighter than the darker of the two starting colors… this is why white is produced in an additive mixture by mixing all colors together • Primary colors are red, blue, green

34. Visual Information Processing

35. Visual Information Processing From Essentials Psychology I • EwaldHering – • Noted that certain kinds of color blindness were not well explained by the Young-Helmholtz theory • Most common form of color blindness is red-green blindness… individuals with this find it difficult to see red or green but not yellow (this goes against the Y-H theory which implies yellow is a mixture of red and green) • Hering argued that yellow was just as much a primary color as red or green or blue… he developed the Opponent Process Theory

36. Color-Deficient Vision • People who suffer red-green blindness have trouble perceiving the number within the design

37. Visual Information Processing Opponent-Process Theory- opposing retinal processes enable color vision(helps to explain afterimages) when “ON” then “OFF” redgreen greenred blueyellow yellowblue black white white black

38. Visual Information Processing From Essentials Psychology I • Young Helmholtz Theory… • Seems to be a good description of visual processing in the retina because cones have been found to be sensitive to red, green, and blue (and not to red-green and blue-yellow) • Opponent Process Theory… • Seems to be a better explanation of color vision at higher levels within the brain—at the optic nerve and beyond

39. Visual Information Processing • Color Constancy • Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

40. Color depends on context

41. Audition • Audition • the sense of hearing • Frequency • the number of complete wavelengths that pass a point in a given time • measured in hertz (Hz)… the human ear can hear between 20 – 20,000 Hz • Pitch • a tone’s highness or lowness • depends on frequency

42. The Intensity of Some Common Sounds Decibels – measuring unit for sound energy… the “loudness” of a sound At close range, the thunder that follows lightning has 120-decibel intensity

43. (air conduction) (boneconduction) (fluid conduction) (auditory ossicles) (Tympanic membrane) (Eustachian tube) (Round window) Added from Essentials Psychology I

44. Added from Essentials Psychology I (incus) (stapes) (malleus) (spiral organ of Corti or auditory receptors) (Round window)

45. Audition- The Ear • Middle Ear • chamber between eardrum and cochlea containing three tiny bones (hammer (malleus), anvil (incus), stirrup (stapes)) 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 sound waves trigger nerve impulses

46. Audition • Middle frequencies distort the basilar membrane at the apex of the cochlea, high frequencies at the base of the cochlea near the oval window • Place Theory • Attempts to explain the reception of sound waves between 5,000 to 20,000 Hz • States that different frequencies stimulate cilia at different places within the cochlea.

47. Audition • Frequency Theory • Accounts for sounds between 20 to 300 Hz • Asserts that neural activity is coded in terms of the rate, rather than the place, at which neurons are triggered • LOW PITCH (or frequency) • Volley theory (or principle) • Accounts for tones from 300 to 5,000 Hz • Fire in volleys that are correlated with the frequency of sound • MID RANGE PITCH (or frequency)

48. How We Locate Sounds Sound waves strike one ear sooner and more intensely than the other. From this information, our nimble brain computes the sound's location. As you might therefore expect, people who lose all hearing in one ear often have difficulty locating sounds.

49. Audition • Conduction Hearing Loss • hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea • Sensorineural Hearing Loss • hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve • lower chance of problem being fixed

50. Touch • Skin Sensations • pressure • only skin sensation with identifiable receptors • warmth • cold • pain