Presentation on theme: "Sensation and Perception Chapter 6"— Presentation transcript:
1 Sensation and Perception Chapter 6 AP Psychology ~ Ms. Justice
2 BIG IDEAS Seeing the World: Some Basic Principles Thresholds Vision HearingOther Important SensesPerceptual OrganizationPerceptual InterpretationIs There Extrasensory Perception?
3 1: What are sensation and perception 1: What are sensation and perception? What do we mean by bottom-up and top-down processing?
4 Sensation & Perception How do we construct our representations of the external world? To represent the world, we must detect physical energy (a stimulus) from the environment and convert it into neural signals. This is a process called sensation. When we select, organize, and interpret our sensations, the process is called perception.Preview Question 1: What are sensation and perception? What do we mean by bottom-up processing and top-down processing?
5 Bottom-up ProcessingAnalysis of the stimulus begins with the sense receptors and works up to the level of the brain and mind.Letter “A” is really a black blotch broken down into features by the brain that we perceive as an “A.”We process this way when we have no prior knowledge: we start at the bottom and work our way up.
6 THE CHT Top-Down Processing Information processing guided by higher-level mental processes as we construct perceptions, drawing on our experience and expectations.THE CHTWe process this way when we have prior knowledge: we start at the top and have to work to process details.
7 Making Sense of Complexity Our sensory and perceptual processes work together to help us sort out complex images.“The Forest Has Eyes,” Bev Doolittle
8 2: What are absolute and difference thresholds, and do stimuli below the absolute threshold have any influence?
9 PsychophysicsA study of the relationship between physical characteristics of stimuli and our psychological experience with them.Physical WorldPsychological WorldLightBrightnessSoundVolumePressureWeightSugarSweet
10 ThresholdsAbsolute Threshold: Minimum stimulation needed to detect a particular stimulus 50% of the time.Proportion of “Yes” ResponsesStimulus Intensity (lumens)Preview Question 2: What is are the absolute and difference thresholds, and do stimuli below the absolute threshold have any influence?
11 Subliminal ThresholdSubliminal Threshold: When stimuli are below one’s absolute threshold for conscious awareness.While much of our information processing occurs automatically (sensation), claims of subliminal persuasion have been discounted through research.
12 Weber’s LawTwo stimuli must differ by a constant minimum percentage (rather than a constant amount), to be perceived as different. Weber fraction: k = dI/I.StimulusConstant (k)Light8%Weight2%Tone0.3%
14 Sensory AdaptationSensory adaptation is the diminishing sensitivity to an unchanging stimulus. After constant exposure to a stimulus, our nerve cells fire less frequently.Put a band aid on your arm and after awhile you don’t sense it.Preview Question 3: What is the function of sensory adaptation?Sensory adaptation offers the freedom to focus on informative changes in our environment: We perceive the world not exactly as it is, but as it is useful for us to perceive it.
15 4: What is the energy that we see as visible light?
16 TransductionVisibleSpectrumTransduction is the transformation of stimulus energy (sights, sounds, smells) into neural impulses our brains can interpret. What we see as visible light is but a thin slice of the whole spectrum of electromagnetic radiation.
17 Physical Characteristics of Light Two physical characteristics of light help determine our sensory experience of them:Wavelength (the distance from one wave peak to the next) determines hue or colorIntensity (the amount of energy in light waves) influences brightness
18 Wavelength (hue/color) VioletIndigoBlueGreenYellowOrangeRed700 nmLong wavelengths400 nmShort wavelengthsIntensity (Brightness)Blue color with varying levels of intensity.As intensity increases or decreases, blue colorlooks more “washed out” or “darkened.”
19 5: How does the eye transform light energy into neural messages?
20 The Eye Label the diagram of the eye, providing a brief description of what each part of the eye does.(page 237)Label the cross section of the retina, explaininghow light entering the eye is transformed intoa neural message. (page 238)Preview Question 5: How does the eye transform light energy into neural messages?
21 The EyePreview Question 5: How does the eye transform light energy into neural messages?
23 Use your textbook – PAGE 239. Test your Blind SpotUse your textbook – PAGE 239.Close your left eye, and fixate your right eye on the black dot. Move the page towards your eye and away from your eye. At some point the car on the right will disappear due to a blind spot.
25 6: How does the brain process visual information?
26 Visual informationGanglion axons forming the optic nerve run to the thalamus, where they synapse with neurons that run to the visual cortex.Any given retinal area relays its information to a corresponding location in the visual cortex, in the occipital lobe at the back of your brain.Figure 6.10, page 240
27 Shape DetectionSpecific combinations of temporal lobe activity occur as people look at shoes, faces, chairs and houses.Ishai, Ungerleider, Martin and Haxby/ NIMH
28 Visual Information Processing Processing of several aspects of the stimulus simultaneously is called parallel processing. The brain divides a visual scene into subdivisions such as color, depth, form, movement, etc.
29 From Sensation to Recognition Figure 6.13 p. 243
30 7: What theories help us understand color vision?
31 Color VisionYoung-Helmholtz trichromatic theory: Thomas Young and Hermann von Helmholtz suggested that the eye must contain three receptors that are sensitive to red, blue and green colors in the 19th century. Years later, researchers confirmed this theory.The retina has three types of color receptors, each sensitive to one of three colors.When we stimulate combinations of these cones, we see other colors.For example, when both red-sensitive and green-sensitive cones are stimulated, we see yellow.Preview Question 7: What theories help us understand color vision?
32 Color BlindnessGenetic disorder in which people are blind to green or red colors. This supports the Trichromatic theory.Ishihara Test
33 Opponent Colors Gaze at the middle of the flag for about 30 Seconds. When it disappears, stare at the dot and reportwhether or not you see Britain's flag.
34 8: What are the characteristics of air pressure waves that we hear as sound?
35 Audition Audition, or hearing, is highly adaptive. We hear a wide range of sounds, but we hear best those sounds with frequencies in a range corresponding to that of the human voice.We are also remarkably attuned to variations in sounds: For example, we easily detect differences among thousands of human voices.
36 Sound Characteristics Sound waves are compressing and expanding air molecules.The wave’s frequency, or length, determine the pitch we experience. Long waves have a low frequency & pitch. Short waves have a high frequency & pitch.The wave’s intensity, or strength, determines the loudness we experience.
37 9: How does the ear transform sound energy into neural messages?
38 The EarSound waves are converted into neural activity: Outer Ear: Collects and sends sounds to the eardrum. 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, containing the cochlea, semicircular canals, and vestibular sacs.
39 CochleaCochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to auditory signals.
40 Intensity (Loudness)Intensity (Loudness): Amount of energy in a wave, determined by the amplitude, relates to the perceived loudness.
41 Loudness of Sound 120dB 70dB 120dB Page 248 Richard Kaylin/ Stone/ Getty Images120dB70dB120dBPage 248
42 10: What theories help us understand pitch perception?
43 Frequency (Pitch)Pitch: The dimension of frequency determined by the wavelength of sound. Frequency theory: The rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone; enabling us to sense its pitch. Best explains how we sense low pitches.Preview Question 10: What theories help us understand pitch perception?Place theory: links the pitch we hear with the place where the cochlea's membrane is stimulated. Best explains how we sense high pitches.A combination of the two theories handle the pitches in the intermediate range.
45 Localization of Sounds Because we have two ears, sounds that reach one ear faster than the other ear causes us to localize the sound.Your right ear would receive a more intense sound from this bell ringing, and it would receive the sound slightly sooner than your left ear.However, the intensity difference and time lag are extremely small.Preview Question 11: How do we locate sounds?
46 12: What are the common causes of hearing loss, and why does controversy surround cochlear implants?
47 HEARING LOSS & DEAF CULTURE Conduction hearing loss: problems with the mechanical system that conducts sound waves to the cochleaSensorineural hearing loss: damage to the cochlea’s hair cell receptors or their associated nerves (more common)Cochlear implants: electronic devices that translate sounds into electric signals that convey some information about sound to the brain.
48 13: How do we sense touch and our body’s position and movement 13: How do we sense touch and our body’s position and movement? How do we experience pain?
49 TOUCHThe sense of touch is a mix of four distinct skin senses—pressure, warmth, cold, and pain.Preview Question 13: How do we sense touch and sense our body’s position and movement? How do we experience pain?Bruce Ayers/ Stone/ Getty Images
50 Body Position &Movement The sense of our body parts’ position and movement is called kinesthesis. The vestibular sense monitors the head (and body’s) position (including balance).Bob Daemmrich/ The Image Works
51 PainPain tells the body that something has gone wrong. Usually pain results from damage to the skin and other tissues. A rare disease exists in which the afflicted person feels no pain: Ashlyn Blocker
52 Gate-Control TheoryMelzack and Wall (1965, 1983) proposed that our spinal cord contains neurological “gates” that either block pain or allow it to be sensed.The “gate” is opened by the activity of pain signals traveling up small nerve fibers, and is closed by activity in large nerve fibers or by information coming from the brain.Gary Comer/ PhototakeUSA.com
56 (Savory meat taste: MSG) Traditionally, taste sensations consisted of sweet, salty, sour, and bitter tastes. Recently, receptors for a fifth taste have been discovered called “Umami”.Preview Question 14: How do we experience taste?SweetSourSaltyBitterUmami(Savory meat taste: MSG)
57 Sensory InteractionWhen one sense affects another sense, sensory interaction takes place. So, the taste of strawberry interacts with its smell and its texture on the tongue to produce flavor.
59 Smell Like taste, smell is a chemical sense. Odorants enter the nasal cavity to stimulate 5 million receptors to sense smell.We can detect 10,000 odors!Preview Question 15: How do we experience smell?Figure 6.25Page 261
60 That is why strong memories are made through the sense of smell. Smell and MemoriesThe brain region for smell (in red) is closely connected with the brain regions involved with memory (limbic system).That is why strong memories are made through the sense of smell.
61 16: How did the Gestalt psychologists understand perceptual organization?
62 Perceptual Organization How do we form meaningful perceptions from sensory information? A group of German psychologists noticed that when given a cluster of sensations people tend to organize them into a gestalt, or an organized, meaningful whole.Preview Question 16: How did the Gestalt psychologists understand perceptual organization?
69 18: How do we see the world in three dimensions?
70 Depth PerceptionDepth perception –the ability to see objects in three dimensions although the images that strike the retina are two dimensional- it enables us to judge distances.Cat with no depth perception:Preview Question 18: How do we see the world in three dimensions?
71 Visual CliffGibson and Walk (1960) suggested that human infants (crawling age) have depth perception using the visual cliff demonstration:
72 Binocular cues are depth cues that depend on two eyes. Retinal disparity, which is the distance between the images received from the two retinas, is a binocular cue that allows us to perceive depth. The greater the disparity between the two images, the closer the object.
73 Monocular cues are depth cues that are available to either eye alone. Relative Size: If two objects are similar in size, we perceive the one that casts a smaller retinal image to be farther away.
74 Monocular CuesInterposition: Objects that occlude (block) other objects tend to be perceived as closer.Rene Magritte, The Blank Signature, oil on canvas,National Gallery of Art, Washington. Collection ofMr. and Mrs. Paul Mellon. Photo by Richard Carafelli.
75 Monocular CuesRelative Height: We perceive objects that are higher in our field of vision to be farther away than those that are lower.
76 Monocular CuesRelative motion: Objects closer to a fixation point move faster and in opposing direction to those objects that are farther away from a fixation point, moving slower and in the same direction.Preview Question 19: How do we perceive motion?
77 Monocular CuesLinear Perspective: Parallel lines, such as railroad tracks, appear to converge in the distance. The more the lines converge, the greater their perceived distance.
80 Perceiving MotionOur brain computes motion based partly on its assumption that shrinking objects are retreating and enlarging objects are approaching. Large objects are also perceived to be moving more slowly that smaller objects. The brain will also perceive continuous movement in a series of slightly varying images. The illusion of movement is also created using the phi phenomenon – when two adjacent stationary lights blink on and off in quick succession
81 20: How do perceptual constancies help us organize our sensations into meaningful perceptions?
82 Perceptual ConstancyRegardless of our viewing angle, distance, and illumination, the top-down processing ability called perceptual constancy allows us to identify people and objects in less time than it takes to draw a breath.Sometimes an object whose actual shape cannot change seems to change shape with the angle of our view.Preview Question 20: How do perceptual constancies help us to organize our sensations into meaningful perceptions?p. 269
83 Color ConstancyPerceiving familiar objects as having consistent color even when changing illumination filters the light reflected by the object.Color Constancy
84 Size-Distance Relationship Experience tells us that a more distant object can create the same size image as a nearer one only if it is actually larger.As a result, we perceive the more distant monster and red bar as larger.Alan Choisnet/ The Image BankFrom Shepard, 1990p. 270
85 Size-Distance Relationship Both girls in the room are of similar height. However, we perceive them to be of different heights as they stand in the two corners of the room.Both photos from S. Schwartzenberg/ The Exploratoriump. 271
86 The Ames room is designed to demonstrate the size-distance illusion. p. 271
87 The color and brightness of square A and B are the same. Lightness ConstancyCourtesy Edward AdelsonThe color and brightness of square A and B are the same.p. 271
88 21: What does research on sensory restriction and restored vision reveal about the effects of experience?
89 Perceptual Interpretation Immanuel Kant ( ) maintained that knowledge comes from our inborn ways of organizing sensory experiences. John Locke ( ) argued that we learn to perceive the world through our experiences.not this guy
90 Sensory Deprivation & Restored Vision How important is experience in shaping ourperceptual interpretation?After cataract surgery, blind adults were able to regain sight. These individuals could differentiate figure and ground relationships, yet they had difficulty distinguishing a circle and a triangle (Von Senden, 1932).Preview Question 21: What does research on sensory restriction and restored vision reveal about the effects of experience?
91 We perceive and recognize individual faces as a whole. Facial RecognitionWe perceive and recognize individual faces as a whole.The same top half of a face paired with two different bottom halves causes us to see the identical top halves as different.After blind adults regained sight, they were able to recognize distinct features, but were unable to recognize faces.Courtesy of Richard LeGrand
93 Perceptual Adaptation Perceptual adaptation - the visual ability to adjust to an artificially displaced or inverted visual fieldExperiments involving inversion glasses reveal that after about a week people can adapt to the change, and even ride a motorcycle, ski, and fly an airplanePreview Question 22: How adaptable is our ability to perceive?Courtesy of Hubert Dolezal
94 23: How do our expectations, contexts, and emotions influence our perceptions?
95 Perceptual SetA perceptual set is a mental predisposition to perceive one thing and not another (top-down processing). Through experience we form concepts, or schemas, that organize and interpret unfamiliar information. The human brain is a hypersensitive face detector – we see faces in random configurations such as cloud formations, rocks, the moon’s landscape, and food.Preview Question 23: How do our expectations, contexts, and emotions influence our perceptions?
96 What you see in the center picture is influenced by flanking pictures. Perceptual SetWhat you see in the center picture is influenced by flanking pictures.
97 Perceptual Set Other examples of perceptual set: Frank Searle, photo Adams/ Corbis-SygmaDick Ruhl(a) Loch ness monster or a tree trunk? (b) Flying saucers or clouds?
98 Context Effects Context can radically alter perception. How tall is the basketball player in yellow?He is actually 6’9”But when compared to 7’9” Sun Ming Ming, he seems short!
99 Context instilled by culture also alters perception. Cultural ContextContext instilled by culture also alters perception.To an East African, the woman sitting is balancing a metal box on her head, while the family is sitting under a tree.
100 Perception is a biopsychosocial phenomenon Perception RevisitedPerception is a biopsychosocial phenomenonPreview Question 24: How do human factors psychologists work to create user-friendly machines and work settings?Figure 6-50p. 279
101 24: How do human factors psychologists work to create user-friendly machines and work settings?
102 Human factors Psychologists These psychologists work with engineers to design appliances, machines, and work settings that fit our natural perceptions and inclinations.
103 25: What are the claims of ESP, and what have most research psychologists concluded after putting these claims to the test?
104 Is There Extrasensory Perception? Perception without sensory input is called extrasensory perception (ESP). A large percentage of scientists do not believe in ESP.Preview Question 25: What are the claims of ESP, and what have most research psychologists concluded after putting these claims to the test?
105 Claims of ESPTelepathy: Mind-to-mind communication. One person sending thoughts and the other receiving them.Clairvoyance: Perception of remote events, such as sensing a friend’s house on fire.Precognition: Perceiving future events, such as a political leader’s death.
106 Claims of ESPMost research psychologists are skeptical about claims of ESP for two main reasons:To believe in ESP you must believe that the brain is capable of perceiving without sensory input.Psychologists and parapsychologists have been unable to replicate ESP phenomena under controlled conditionsNo psychic has been able to predict the outcome of a lottery jackpot or to make millions on the stock market.No psychic was able to predict 9/11, or to collect the $50 million reward for locating Osama bin Laden.