Unit 4: Sensation and Perception

Transcription

1 Unit 4: Sensation and Perception

2 What are the function of THERMORECPTORS? Thermoreceptors are responsible for the sensation of non-painful warmth or cold sensations. They have ion channels that change voltage across the nerves in relation to temperature. Have you ever turned the water on really hot and it felt cold?

3 How does thermosensation help us to maintain homeostasis? The main function of thermosensation is to maintain homeostasis. One of the most important examples of homeostasis is the regulation of body temperature which is controlled by the specific areas in the hypothalamus that receive information form thermoreceptors in the skins and in some of the major blood vessels.

4 How do our eyes collect light energy? Do Now: Do you think the color green is the same for you as it is for me? Explain your answer. Homework: bring in a plastic top of a container (example: the top of a coffee can)

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6 What is Vision? Vision is the dominant sense in human beings. There are many steps in gathering visual information.

7 Step One Light is reflected off objects and are gathered by the eye. The color we perceive depends on several factors: Light intensity (energy) Light wavelength (determines hue)

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9 Step Two The reflected light first enters the eye through the cornea The light then goes through the pupil The pupil is like the shutter of a camera The muscles that control the pupil (the iris) open it to let more light in, or make is smaller to let less light in.

10 Step Two continued Through a process called accommodation, the light is then focused by the lens. Try This: Hold up one finger and focus on it for a few seconds. Now focus on the wall behind your finger. Now refocus on your finger. Do you see the change? This is your lens working!

11 s e h t l l i Where w e s e b s e g e messa? n i a r b e nt in th Step Three: Transduction Transduction: the translation of incoming stimuli into neural signals. This is done in the cells called cones and rods. Cones are activated by color Rods are activated by black and white.

12 Benham s Disks

13 Our Blind Spot What is a blind spot? Humans have blind spots. Our blind spot is the area on the retina that does not have receptors that respond to light.

14 Let s Find out Blind Spot! Close your right eye. Hold your blind spot tester strip about 20 inches from your face. With your left eye, look at the smiley face and slowly pull the tester towards your face. Did you see the sad face disappear?

15 Step Four: In the Brain The information collected by our eye is sent to the occipital lobes of our brain. This is where some researchers say sensation ends and perception begins.

16 Hubel and Weisel Perception researchers. They discovered that groups of neurons in the visual cortex respond to different types of visual images. The visual cortex has feature detectors for vertical lines, curves, and motion.

17 What two theories are used to explain Color Vision? Do Now: have you ever stared at an image and then closed your eyes and you see a different color? Why do you think this is?

18 Trichromatic Theory Trichromatic Theory was created by Thomas Young and Hermann von Helmholtz. They hypothesized that we have three types of cones I the retina. These cones detect the different colors blue, red and green.

19 Trichromatic Theory: the experiment Helmholtz used color-matching experiments where participants would alter the amounts of three different wavelengths of light to match a test color. Participants could not match the colors if they used only two wavelengths, but could match any color in the spectrum if they used three.

20 Trichromatic Theory: what do the critics say? This theory fails to explain visual phenomena such as afterimages.

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25 What happened??? Why do you think you saw a different color when you closed your eyes?

26 Dichromatic Color Blindness Someone with Dichromatic Color Blindness cannot see either red/green shades or blue/yellow shades.

27 Monochromatic Color Blindness Someone with Monochromatic Color Blindness only sees shades of grey.

28 Opponent-Process Theory This theory states that the sensory receptors arranged in the retina come in pairs: Yellow/blue Red/green Black/white If one sensor is stimulated, its pair is inhibited from firing.

29 Critical Thinking How does Opponent-Process Theory of Color Vision explain the visual phenomena of afterimages and colorblindness?

30 Summary A combination of both the Trichromatic Theory and the Opponent-Process Theory are necessary to fully explain color vision. WHY???

31 How does our sense of hearing work? s g in th e m o s r ea h n a c s g o d e m o Do Now: how c we can not?

32 Auditory Sense Our auditory sense used energy in the form of waves. What other sense is this like? Sound waves are created by vibrations, which travel through the ear, and are collected by our ears.

33 Our ears collect waves Sound waves are collected in our outer ear, or pinna. The waves travel down the ear canal. The waves reach the eardrum or typanic membrane.

34 In the Middle Ear The ear drum connects with the hammer The hammer is connected to the anvil The anvil is connected to the stirrup

35 In the Inner Ear The vibration of the ear drum is transmitted by the middle ears to the oval window. The oval window is attached to the cochlea. The cochlea is filled with fluid and lined with hair cells which connect to neurons The fluid in the cochlea moves when the oval window is stimulated by the middle ear. This causes the hair to move which then activates the neurons.

36 Pitch Theories

37 Place Theory According to Place Theory, the hair cells in our cochlea respond to different frequencies of sound based on where they are located in the cochlea. Some of these hairs bend in response to high pitches, some to low.

38 Frequency Theory Research demonstrates that place theory explains how hair cells sense high tones, but not low tones. Lower tones are sensed by the rate at which the cells fire. This theory states that we sense pitch because the hair cells fire at different rates or frequencies

39 How does our understanding of how hearing works help us to understand deafness? Deafness occurs when something goes wrong with the system of conducting the sound to the cochlea.

40 Our Sense of Touch Do Now: why is our sense of touch considered an energy sense?

41 Touch: When our skin is indented, pierced or experiences a change in temperature, our sense of touch is activated by this energy. Some nerves respond to temperature, while others respond to pressure. If our temperature receptors are stimulated sharply, pain receptors will fire. This is to warn us of potential dangers.

42 Gate-Control Theory of PAIN Gate-Control Theory explains that some pain messages have a higher priority than others. When a high priority pain messages is sent, the gate is opened for that sensation and closed for all others. How does this explain the sensation of having an itch and then scratching it?

43 Summary Explain touch through concepts you have learned in our unit on neuroanatamy. What role do thermoreceptors play in our sense of touch?

44 How do our Chemical Senses work? Do Now: which of our 5 senses are chemical senses?

45 Our taste buds are located on papillae which are the bumps on our tongue. We sense four types of tastes: Sweet Salty Sour Bitter

46 Sense of Taste continued The more densely packed our taste buds, the more chemicals we absorb. The more chemicals absorbed, the more intense the food tastes. The flavor of food is actually a combination of taste and smell.

47 Our Sense of Smell (Olfaction) Our sense of smell depends on chemicals. Molecules of substances rise in the air and are drawn into our nose.

48 Our Sense of Smell continued Molecules enter the nose and settle in a mucous membrane at the top of each nostril and are then absorbed by receptor cells. Researchers estimate that there are over 100 different types of receptor cells. These cells are attached to the olfactory bulb which sends the information to the brain. Information is sent to the amygdala and then the hippocampus. The hippocampus is part of the limbic system which is responsible for emotional impulses and memories.

49 Aim: What are our body position senses? a n o i t i s o p y d o b s i w o h : w o Do N sense?

50 Vestibular Sense Our vestibular sense tells us about how our body is oriented in space. The inner ear is crucial in this process. Think about riding a roller coaster sometimes you get nauseous and/or dizzy.

51 Kinesthetic Sense k c a b d e e f s u s e iv g e s n e s ic t e h t s e in k r Ou of n io t a t n ie r o d n a n about the positio. s t r a p y d o b ic if c e sp with e e n k r u o y h c u o t ou can y, e s n e s is h t f o e s ts c e t e Becau d e s n e s ic t e h t r kines u o y e s u a c e b y lt u ic no diff r hand. u o y o t n io t la e r in where your knee is

52 Summary How do our body position senses use our chemical and energy senses to function properly?

53 What are the principles of Visual Perception? Do Now: how do you think an optical illusion work?

54 Figure-Ground Relationship When we look at an image, part of our perception of that image is the figure-ground relationship. This is when our brain determines which part of the image is the figure, and which is the background.

55 Optical Illusions Let s examine the following optical illusions together!

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60 What are the principles of Gestalt Psychology in relation to visual perception? What is Gestalt Psychology? Gestalt Psychologists observe people in the real world and focus on the whole, not the parts.

61 Gestalt Rules Gestalt Psychologists say that we perceive images a part of a group, not isolated elements. Gestalt Psychologists thought this process was innate and inevitable (meaning its nature)

62 Gestalt Rules Proximity: objects that are close together are more likely to be perceived as belonging to the same group.

63 Gestalt Rules Similarity: Objects that are similar in appearance are more likely to be perceived as belonging in the same group.

64 Gestalt Rules Continuity: Objects that form a continuous form are more likely to be perceived as belonging to the same group.

65 Gestalt Rules Closure: Similar to top-down processing. Objects that make up a recognizable image are more likely to be perceived as belonging in the same group even if the image contains gaps that the mind needs to fill in.

66 Summary How do the Gestalt Rules of visual perception apply to people? Give specific examples.

67 What is Constancy in relation to visual perception? Do Now: what does it mean to be constant?

68 Constancy Every object we look at changes slightly due to a variety of reasons. Our angle of vision Variations in light

69 Constancy Our ability to maintain constant perception of an object despite these changes is called constancy.

70 Types of Constancy Size Constancy: we keep a constant size in mind for an object. Because of this, it does not matter if we are far away or close up to the object

71 Types of Constancy Shape Constancy: we keep a constant shape in our mind for each object. no matter what angle we look at the object, we know what shape the object is supposed to be.

72 Types of Constancy Brightness Constancy: we perceive objects as being a constant color even as the light reflecting off of the object changes.

73 Summary Give one example of how you use constancy on a daily basis. How would your perception be altered if you did not use constancy?

74 What is Perceived Motion? Do Now: how do you think flip books work from a perspective of a perception researcher?

75 Perceived Motion Our brains are able to detect how fast images move across our retinas and take into account our own movement. Sometimes, our brain perceives objects to be moving when they are not. The stroboscopic effect is an example of this and is used in flip books.

76 Perceived Motion continued Phi Phenomenon: when a series of light bulbs are turned on and off at a particular rate will appear to be one moving light. Example: movie marquees and holiday lights

77 Perceived Motion continued Autokinetic Effect: if a spot of light is projected steadily on the same place on a wall of a dark room, it will appear to move if you stare at it.

78 Summary Give an example for each of the following phenomenon: Stroboscopic effect Phi phenomenon Autokinetic effect

79 How did Eleanor Gibson use the Visual Cliff Experiment to explain depth cues? Do Now: have you ever jumped into a pool? How did you know how far away the water was?

80 Eleanor Gibson designed the Visual Cliff Experiment to see if infants had developed depth perception. What is depth perception? Depth perception allows us to view the world as 3 dimensional, not 2 dimensional.

81 What was the Visual Cliff Experiment? A visual cliff involves an apparent, but not actual drop from one surface to another. A visual cliff is created by connecting a transparent (see through) glass surface to an opaque patterned surface. The floor below has the same pattern as the opaque (can t see through it) surface. This apparatus creates the visual illusion of a cliff, while protecting the subject from injury

82 What was the Visual Cliff Experiment?

83 What cues do we use to determine depth? Monocular Cues: artists use these cues to imply (suggest) depth in their drawings. Linear Perspective Relative Size Cue Interposition Cue Texture Gradient Shadowing

84 Linear Perspective

85 Relative Size Cue

86 Interposition Cue

87 Texture Gradient

88 Shadowing

89 What cues do we use to determine depth? Binocular Cues: binocular cues result from our anatomy (nature). Binocular disparity: We see the world through two eyes are a certain distance apart, and this feature gives us the ability to perceive depth. Convergence: as an object moves closer to our face, we cross our eyes to maintain focus.

90 Does culture affect our perception? Research indicates that some of perceptual rules are learned (nurture). Examples: linear perspective in art and optical illusions.

91 Muller-Lyer Illusion