1. Sensation and Perception

2. THREE DEFINITONS Adaptation: –the decreasing response of the sense organs, the more they are exposed to a continuous level of stimulation Sensation versus perception: –relatively meaningless bits of information that result when the brain processes electrical signals that come from the sense organs –perceptions: –meaningful sensory experiences that result after the brain combines hundreds of sensations

3. THREE DEFINITONS (CONT.) eyes, ears, nose, skin, and tongue are complex, miniaturized, living sense organs that automatically gather information about your environment Transduction: –process in which a sense organ changes, or transforms, physical energy into electrical signals that become neural impulses, which may be sent to the brain for processing

4. PERCEPTUAL THRESHOLDS Threshold –a point above which a stimulus is perceived and below which it is not perceived –threshold determines when we first become aware of a stimulus

5. PERCEPTUAL THRESHOLDS (CONT.) Becoming aware of a stimulus –Gustav Fechner defined the absolute threshold as the smallest amount of stimulus energy (such as sound or light) that can be observed or experienced –Absolute threshold the intensity level of a stimulus such that a person will have a 50% chance of detecting it

7. SUBLIMINAL PERCEPTION Subliminal Message –brief auditory or visual message that is presented below the absolute threshold –means that there is less than a 50% chance that the message will be perceived Self-fulfilling prophecies –involve having strong beliefs about changing some behavior and then acting, unknowingly, to change that behavior

8. PERCEPTUAL THRESHOLDS (CONT.) Subliminal stimulus –has an intensity that gives a person less than a 50% chance of detecting the stimulus –breast cancer accuracy problems –looking for ways to lower the threshold for detecting cancerous tumors and thus save patients –recently, use of digital mammograms (allows for images to be enhanced or magnified) is better in detecting cancerous tumors in women

10. PERCEPTUAL THRESHOLDS (CONT.) E. H. Weber –worked on the problem of how we judge whether a stimulus, such as loud music, has increased or decreased in intensity –concept of just noticeable difference (JND) –refers to the smallest increase or decrease in the intensity of a stimulus that a person is able to detect Weber’s law –The increase in intensity of a stimulus needed to produce a just noticeable difference grows in proportion to the intensity of the initial stimulus.

12. SENSATION VERSUS PERCEPTION Basic Differences –Sensations our first awareness of some outside stimulus outside stimulus activates sensory receptors, which in turn produce electrical signals that are transformed by the brain into meaningless bits of information –Perceptions the experience we have after our brain assembles and combines thousands of individual sensations into a meaningful pattern or image

14. SENSATION VERSUS PERCEPTION (CONT.) Changing sensation into perception –Stimulus change of energy in the environment, such as light waves, sound waves, mechanical pressure, or chemicals –Transduction change physical energy into electrical signals electrical signals are changed into impulses that travel into the brain –Brain impulses from senses first go to different primary areas of the brain

15. SENSATION VERSUS PERCEPTION (CONT.) Changing sensation into perception –brain: association areas –sensation impulses are sent to the appropriate association area in the brain Personalized perceptions –each of us has a unique set of personal experiences, emotions, and memories that are automatically added to our perceptions by other areas of the brain

16. EYE: VISION Structure and function –eyes perform two separate processes –first: gather and focus light into precise area in the back of eye –second: area absorbs and transforms light waves into electrical impulses –process called transduction

17. EYE: VISION (CONT.) Stimulus: Light Waves –Invisible—too short wave lengths too short gamma rays, x-rays, ultraviolet rays –Visible—just right Visible spectrum Particular segment of electromagnetic energy that we can see because these waves are the right length to stimulate receptors in the eye –Invisible—too long wave lengths longer Radar, FM, TV, shortwave, AM

18. EYE: VISION (CONT.)

19. Structure and function –Vision: 7 steps Image reversed Light waves Cornea Pupil Iris Lens Retina

20. EYE: VISION (CONT.) Structure and function –Image reversed In the back of the eye, objects appear upside down. somehow the brain turns the objects right side up –Light waves light waves are changed from broad beams to narrow, focused ones

21. EYE: VISION (CONT.) Structure and function –Cornea rounded, transparent covering over the front of your eye –Pupil round opening at the front of the eye that allows light waves to pass into the eye’s interior

22. EYE: VISION (CONT.) Structure and function –Iris circular muscle that surrounds the pupil and controls the amount of light entering the eye –Lens transparent, oval structure whose curved surface bends and focuses light waves into an even narrower beam

23. EYE: VISION (CONT.) Structure and function –Retina located at the very back of the eyeball, is a thin film that contains cells that are extremely sensitive to light light sensitive cells, called photoreceptors, begin the process of transduction by absorbing light waves

24. EYE: VISION (CONT.)

25. Retina: –three layers of cells back layer contains two kinds of photoreceptors that begin the process of transduction change light waves into electrical signals rod located primarily in the periphery cone located primarily in the center of the retina called the fovea

26. EYE: VISION (CONT.) rods: –photoreceptor that contain a single chemical, called rhodopsin –activated by small amounts of light –very light sensitive –allow us to see in dim light –see only black, white and shades of gray

27. EYE: VISION (CONT.) cones: –photoreceptors that contain three chemicals called opsins –activated in bright light –allow us to see color –cones are wired individually to neighboring cells –allows us to see fine detail

28. EYE: VISION (CONT.)

29. Visual pathways: Eye to brain –Optic nerve –Primary visual cortex –Visual association areas

30. EYE: VISION (CONT.)

31. Visual pathways: eye to brain –Optic nerve nerve impulses flow through the optic nerve as it exits from the back of the eye the exit point is the “blind spot” the optic nerves partially cross and pass through the thalamus the thalamus relays impulses to the back of the occipital lobe in the right and left hemisphere

32. EYE: VISION (CONT.) Visual pathways: eye to brain –Primary visual cortex the back of the occipital lobes is where primary visual cortex transforms nerve impulses into simple visual sensations –Visual association areas the primary visual cortex sends simple visual sensations to neighboring association areas

33. EYE: VISION (CONT.) Color Vision –Trichromatic theory three different kinds of cones in the retina each cone contains one of the three different light- sensitive chemicals, called opsins each of the three opsins is most responsive to wavelengths that correspond to each of the three primary colors blue, green, red all colors can be mixed from these primary colors

34. EYE: VISION (CONT.) Opponent-Process Theory –Afterimage visual sensation that continues after the original stimulus is removed ganglion cells in retina and cells in thalamus respond to two pairs of colors—red-green and blue-yellow when excited, respond to one color of the pair when inhibited, respond to complementary pair

35. EYE: VISION (CONT.) Color Blindness –inability to distinguished two or more shades in the color spectrum –Monochromatic: total color blindness black and white result of only rods and one kind of functioning cone –Dichromatic: trouble distinguishing red from green two kinds of cones inherited genetic defect mostly in males See mostly shades of green

36. RULES OF ORGANIZATION Structuralist versus Gestalt psychologists –Structuralists believed that you add together hundreds of basic elements to form complex perceptions –Gestaltists believe our brains follow a set of rules that specify how individual elements are to be organized into a meaningful pattern, or perception

37. RULES OF ORGANIZATION (CONT.) Organizational rules –rules of organization: identified by Gestalt psychologists specify how our brains combine and organize individual pieces or elements into a meaningful perception –Figure-ground states: in organizing stimuli, we tend to automatically distinguish between a figure and a ground –Similarity states: in organizing stimuli, we group together elements that appear similar

38. RULES OF ORGANIZATION (CONT.) –Closure states: in organizing stimuli, we tend to fill in any missing parts of a figure and see the figure as complete –Proximity states: in organizing stimuli, we group together objects that are physically close to one another –Simplicity states: stimuli are organized in the simplest way possible –Continuity states: in organizing stimuli, we tend to favor the smooth or continuous paths when interpreting a series of points or lines

39. PERCEPTUAL CONSTANCY Size, shape, brightness & color constancy –Size constancy refers to our tendency to perceive objects as remaining the same size even when their images on the retina are continually growing or shrinking –Shape constancy refers to our tendency to perceive an object as retaining its same shape even though when we view it from different angles, its shape is continually changing its image on the retina

40. PERCEPTUAL CONSTANCY (CONT.) Size, shape, brightness & color constancy –Brightness constancy refers to the tendency to perceive brightness as remaining the same in changing illumination –Color constancy refers to the tendency to perceive colors as remaining stable despite differences in lighting

41. DEPTH PERCEPTION Binocular (two eyes) depth cues –Depth perception refers to the ability of your eye and brain to add a third dimension, depth, to all visual perceptions, even though images projected on the retina are in only two dimensions, height, and width –Binocular depth cues depends on the movement of both eyes –Convergence refers to a binocular cue for depth perception based on signals sent from muscles that turn the eyes

42. DEPTH PERCEPTION (CONT.) Retinal disparity –refers to a binocular depth cue that depends on the distance between the eyes

43. DEPTH PERCEPTION (CONT.)

44. Monocular depth cues –produced by signals from a single eye –Linear perspective monocular depth cue that results as parallel lines come together, converge, in the distance –Relative size monocular depth cue that results when we expect two objects to be the same size and they are not –Interposition monocular depth cue that comes into play when objects overlap

45. DEPTH PERCEPTION (CONT.) Monocular depth cues –Light and shadow monocular depth cues where brightly lit objects appear closer, while objects in shadows appear farther away –Texture gradient monocular depth cue in which areas with sharp, detailed texture are interpreted as being closer and those with less sharpness and poorer detail are perceived as more distant

46. DEPTH PERCEPTION (CONT.) Monocular depth cues –Atmospheric perspective monocular depth cue that is created by the presence of dust, smog, clouds, or water vapor –Motion parallax monocular depth cue based on the speed of moving objects

47. ILLUSIONS Strange perceptions –Illusion a perceptual experience in which you perceive an image as being so strangely distorted that, in reality, it cannot and does not exist –Impossible figure perceptual experience in which a drawing seems to defy basic geometric laws

48. ILLUSIONS (CONT.)

49. EAR: AUDITION Stimulus: –Sound waves stimuli for hearing (audition) ripples of different sizes sound waves travel through space with varying heights and frequency –Height distance from the bottom to the top of a sound wave called amplitude –Frequency number of sound waves occurring within one second

50. EAR: AUDITION (CONT.) Loudness –subjective experience of a sound’s intensity –brain calculates loudness from specific physical energy (amplitude of sound waves) Pitch –subjective experience of a sound being high or low –brain calculates from specific physical stimuli –speed or frequency of sound waves –measured in cycles (how many sound waves in one second)

51. EAR: AUDITION (CONT.) Measuring sound waves –decibel: unit to measure loudness –threshold for hearing: 0 decibels (no sound) 140 decibels (pain and permanent hearing loss)

52. EAR: AUDITION (CONT.)

53. Outer, middle, and inner ear –Outer ear consists of three structures external ear auditory canal tympanic membrane

54. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Outer ear external ear –oval shaped structure that protrudes from the side of the head function –pick up sound waves and then send them down the auditory canal

55. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Outer ear auditory canal –long tube that funnels sound waves down its length so that the waves strike the tympanic membrane (ear drum)

56. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Outer ear tympanic membrane –taut, thin structure commonly called the eardrum –Sound waves strike the tympanic membrane and cause it to vibrate

57. EAR: AUDITION (CONT.)

58. Outer, middle, and inner ear –Middle ear bony cavity sealed at each end by membranes. the membranes are connected by three tiny bones called ossicles hammer, anvil and stirrup –hammer is attached to the back of the tympanic membrane –anvil receives vibrations from the hammer –stirrup makes the connection to the oval window (end membrane)

59. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Inner ear contains two structures sealed by bone –cochlea: involved in hearing –vestibular system: involved in balance

60. EAR: AUDITION (CONT.) Cochlea –bony coiled exterior that resembles a snail’s shell –contains receptors for hearing –function is transduction –transforms vibrations into nerve impulses that are sent to the brain for processing into auditory information

61. EAR: AUDITION (CONT.)

62. Auditory brain areas –sensations and perceptions –two step process occurs after the nerve impulses reach the brain –primary auditory cortex –top edge of temporal lobe –transforms nerve impulses into basic auditory sensations –auditory association area –combines meaningless auditory sensations into perceptions, which are meaningful melodies, songs, words, or sentences

63. VESTIBULAR SYSTEM: BALANCE Position and balance –vestibular system is located above the cochlea in the inner ear –includes semicircular canals –bony arches set at different angles –each semicircular canal is filled with fluid that moves in response to movements of your head –canals have hair cells that respond to the fluid movement –function of vestibular system –include sensing the position of the head, keeping the head upright, and maintaining balance

64. CHEMICAL SENSES Taste –chemical sense because the stimuli are various chemicals –tongue –surface of the tongue –taste buds

65. CHEMICAL SENSES (CONT.) Tongue –Five basic tastes sweet salty sour bitter umami: meaty-cheesy taste

66. CHEMICAL SENSES (CONT.) Surface of the tongue –chemicals, which are the stimuli for taste, break down into molecules –molecules mix with saliva and run into narrow trenches on the surface of the tongue –molecules then stimulate the taste buds

67. CHEMICAL SENSES (CONT.) Taste buds –shaped like miniature onions –receptors for taste –chemicals dissolved in saliva activate taste buds –produce nerve impulses that reach areas of the brain’s parietal lobe –brain transforms impulses into sensations of taste Flavor –combination of taste and smell

68. CHEMICAL SENSES (CONT.)

69. Smell, or olfaction –Steps for olfaction Stimulus Olfactory cells Sensation and memories Functions of olfaction

70. CHEMICAL SENSES (CONT.)

71. Smell, or olfaction –Stimulus we smell volatile substances volatile substances are released molecules in the air at room temperature example: –skunk spray, perfumes, warm brownies; not glass or steel

72. CHEMICAL SENSES (CONT.) Smell, or olfaction –Olfactory cells receptors for smell are located in a I-inch-square patch of tissue in the uppermost part of the nasal passages. olfactory cells are covered in mucus which dissolve volatile molecules and stimulate the cells the cells trigger nerve impulses that travel to the brain which interprets the impulses as different smells

73. CHEMICAL SENSES (CONT.) Smell, or olfaction –Sensations and memories nerve impulses travel to the olfactory bulb impulses are relayed to the primary olfactory cortex cortex transforms nerve impulses into olfactory sensations can identify as many as 10,000 different odors we stop smelling our deodorants or perfumes because of decreased responding called adaptation

74. CHEMICAL SENSES (CONT.) Smell, or olfaction –Functions of olfaction one function: to intensify the taste of food second function: to warn of potentially dangerous foods third function: elicit strong memories; emotional feelings

75. TOUCH Touch –includes pressure, temperature, and pain

76. TOUCH (CONT.)

77. Receptors in the skin –skin –hair receptors –free nerve endings –Pacinian corpuscle

78. TOUCH (CONT.) Skin –outermost layer –thin film of dead cells containing no receptors –just below, are first receptors which look like groups of threadlike extensions –middle and fatty layer –variety of receptors with different shapes and functions –some are hair receptors

79. TOUCH (CONT.) Hair receptors –free nerve endings wrapped around the base of each hair follicle –hair follicles fire with a burst of activity when first bent –if hair remains bent for a period of time, the receptors will cease firing –sensory adaptation –example: wearing a watch

80. TOUCH (CONT.) Free nerve endings –near bottom of the outer layer of skin –have nothing protecting or surrounding them Pacinian corpuscle –in fatty layer of skin –largest touch sensor –highly sensitive to touch –responds to vibration and adapts very quickly

81. TOUCH (CONT.) Brain areas –somatosensory cortex –located in the parietal lobe –transforms nerve impulses into sensations of touch temperature, and pain

82. PAIN What causes pain? –pain: unpleasant sensory and emotional experience that may result from tissue damage, one’s thoughts or beliefs, or environmental stressors –pain results from many different stimuli

83. PAIN (CONT.)

84. How does the mind stop pain? –gate control theory of pain –nonpainful nerve impulses compete with pain impulses in trying to reach the brain –creates a bottleneck or neutral gate –shifting attention or rubbing an injured area decreases the passage of painful impulses –result: pain is dulled

85. PAIN (CONT.) Endorphins –chemicals produced by the brain and secreted in response to injury or severe physical or psychological stress –pain reducing properties of endorphins are similar to those of morphine –brain produces endorphins in situations that evoke great fear, anxiety, stress or bodily injury as well as intense aerobic activity

86. PAIN (CONT.) Dread –connected to pain centers in brain –not the act itself that people fear –time waiting before event causes dread Acupuncture –trained practitioners insert thin needles into various points on the body’s surface and then manually twirls or electrically stimulates the needles –after 10-20 minutes of stimulation, patients often report a reduction in various kinds of pain