Exam 1
• Top Score: 50 • Mean: 43.4 • Median: 44.5 • Mode: 44 • SD: 5.11 Sensation & Perception • Problems: – Start time screwed up for both; got resolved within 15 minutes – Duplicate question (my fault) – Wrong answers for 3rd graph question (changed within 15 minutes, only Chapter 6 affected 5 students; their scores have been corrected) • HELP LINE: 1-800-936-6899 Psy 12000.003 • Suggestions: – No go back?
1 – Others? 2
Announcement Sensation & Perception How do we construct our representations of the external • Participants Needed world? – $10 to participate in experiment. • To represent the world, we must first detect – You (ask a friend, too) physical energy (a stimulus) from the environment and convert it into neural • Contact: Eric Wesselmann signals. This is a process called sensation. – [email protected] • Wilhelm Wundt: “Father of Experimental Psychology” – Introspectionism When we select, organize, and interpret our sensations, the process is called perception. 3 4
The Dark Restaurant The Senses
“I went to this restaurant in Berlin…” • Traditional Five: – Sight – Hearing – Touch – Smell • http://www.unsicht-bar.com/unsicht-bar- – Taste berlin-v2/en/html/home_1_idea.html • Six others that humans have – Nociception (pain) – Equilbrioception (balance) – Proprioception & Kinesthesia (joint motion and acceleration) – Sense of time – Thermoception (temperature) – Magnetoception (direction)
5 6
1 Bottom-up Processing Top-Down Processing
Analysis of the stimulus begins with the sense receptors Information processing guided by higher-level and works up to the level of the brain and mind. mental processes as we construct perceptions, drawing on our experience and expectations.
Letter “A” is really a black blotch broken down into features THE CHT by the brain that we perceive as an “A.”
7 8
Top-Down or Bottom-Up? Making Sense of Complexity
Our sensory and perceptual processes work together to help us sort out complex images.
Learned depth cues make this a 9 10 top down perceptual distortion “The Forest Has Eyes,” Bev Doolittle
Sensing the World Exploring the Senses
Senses suit an organism’s needs, . What stimuli cross our threshold for conscious enabling survival. awareness?
A frog feeds on flying insects so visual . Could we be influenced by stimuli too weak acuity must be very sensitive; (subliminal) to be perceived? a male silkworm moth is sensitive to female sex-attractant odor; and we as human beings are sensitive to . Why are we unaware of unchanging stimuli, like a sound frequencies that represent the band-aid on our skin? range of human voice.
11 12
2 Psychophysics 22nd October 1850
A study of the relationship between physical characteristics of stimuli and our psychological A relative increase in experience with them. mental intensity, Fechner Psychological realized, might be Physical World World measured in terms of the Light Brightness relative increase in physical energy required Sound Volume to bring it about.
Pressure Weight Gustav Fechner (1801-1887) Sugar Sweet 13 14
Detection Thresholds Absolute Threshold: Minimum stimulation needed for Absolute an individual to detect a particular stimulus 50% of the Threshold time.
Intensity
No No No Yes Yes Observer’s Response Detected Proportion of “Yes” Responses of “Yes” Proportion 0.00 0.50 1.00
Tell when you (the observer) detect the light. 15 0 5 10 15 20 25 16 Stimulus Intensity (lumens)
Subliminal Threshold Difference Threshold
Subliminal Threshold: When Difference Threshold: Minimum difference between two stimuli are below one’s stimuli required for detection 50% of the time, also called absolute threshold for just noticeable difference (JND). conscious awareness.
Difference Threshold
Kurt Scholz/ Superstock No No Yes Observer’s Response
17 Tell when you (observer) detect a difference in the light. 18
3 Weber’s Law Signal Detection Theory (SDT)
Two stimuli must differ by a constant minimum Predicts how and when we detect the presence of a percentage (rather than a constant amount), to be faint stimulus (signal) amid background noise (other perceived as different. Weber fraction: k = δI/I. stimulation). SDT assumes that there is no single absolute threshold and detection depends on: Stimulus Constant (k) Light 8%
Person’s experience Carol Lee/ Tony Stone Images Weight 2% Expectations Motivation Tone 3% Level of fatigue
19 20
SDT Matrix Sensory Adaptation
The observer decides whether she hears the tone or not, Diminished sensitivity as a consequence of constant based on the signal being present or not. This translates stimulation. into four outcomes.
Decision Yes No
Present Hit Miss Signal False Correct Absent Put a band aid on your arm and after awhile Alarm Rejection you don’t sense it. 21 22
Now you see, now you don’t Sensation without Perception Video on Visual Prosopagnosia
23 24
4 Sense of Touch Skin Senses
The sense of touch is a mix of four distinct skin senses Only pressure has identifiable receptors. All other skin —pressure, cold, warmth, and pain. sensations are variations of pressure, warmth, cold and pain.
Pressure Vibration Vibration Bruce Ayers/ Stone/ Getty Images Images Getty Stone/ Ayers/ Bruce 25 Burning hot Cold, warmth and pain 26
Touch Sensation/Perception Taste
• The intense tickling Traditionally, taste sensations consisted of sweet, salty, sensation that makes sour, and bitter tastes. Recently, receptors for a fifth you laugh taste have been discovered called “Umami”. uncontrollably… – Only happens when someone else tickles you – You cannot tickle yourself and get this response (Blakemore, et al., Sweet Sour Salty Bitter Umami 2000) (Fresh • Why? Chicken)
27 28
Sensory Interaction
When 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. Taste
Scientific American Frontiers: Tasters and Super-tasters
29 30
5 Smell Age, Gender, and Smell
Like taste, smell is a chemical sense. Odorants enter the Ability to identify smell peaks during early adulthood, nasal cavity to stimulate 5 million receptors to sense but steadily declines after that. Women are better at smell. Unlike taste, there are many different forms of detecting odors than men. smell.
31 32
Example of Sensory Interaction Smell and Memories Audition/Vision
The brain region for smell Count the Fs: (in red) is closely connected with the brain FINISHED FILES ARE THE RESULTS regions involved with OF YEARS OF SCIENTIFIC STUDY memory (limbic system). COMBINED WITH THE EXPERIENCE That is why strong memories are made OF YEARS. through the sense of smell.
33 34
Pheromones, Odor, and Sweaty T-Shirts • http://www.pbs.org/wgbh/evolution/library/ 01/6/l_016_08.html • Adaptive to prefer mate with different Vision immune system to one’s own: MHC (major histocompatibility locus) • Women preferred the scents of T-shirts worn by men whose MHC
genes were different from their own. 35 36
6 Transduction The Stimulus Input: Light Energy
In sensation, the transformation of stimulus energy into neural impulses.
Phototransduction: Conversion of light energy into neural impulses that the brain can understand. Visible Spectrum Both Photos: Thomas Eisner Eisner Thomas Photos: Both
37 38
Light Characteristics Wavelength (Hue)
Hue (color) is the dimension of color . Wavelength (hue/color) determined by the wavelength of the . Intensity (brightness) light. . Saturation (purity) Wavelength is the distance from the peak of one wave to the peak of the next.
39 40
Wavelength (Hue) Intensity (Brightness)
Intensity Amount of Violet Indigo Blue Green Yellow Orange Red energy in a wave determined by the amplitude. It 400 nm 700 nm is related to Short wavelengths Long wavelengths perceived brightness. Different wavelengths of light result in different colors.
41 42
7 Intensity (Brightness) Purity (Saturation)
Saturated
Saturated
Blue color with varying levels of intensity. Monochromatic light added to green and red As intensity increases or decreases, blue color makes them less saturated. looks more “washed out” or “darkened.” 43 44
Color Solid The Eye
Represents all three characteristics of light stimulus on this model.
http://www.visionconnection.org 45 46
Parts of the eye The Lens Lens: Transparent 1. Cornea: Transparent tissue where light enters the structure behind the pupil eye. that changes shape to focus 2. Iris: Muscle that expands and contracts to change images on the retina. the size of the opening (pupil) for light. 3. Lens: Focuses the light rays on the retina. Accommodation: The 4. Retina: Contains sensory receptors that process process by which the eye’s visual information and sends it to the brain. lens changes shape to help focus near or far objects on the retina.
47 48
8 The Lens Retina
Nearsightedness: A Retina: The light- condition in which sensitive inner nearby objects are seen surface of the eye, more clearly than distant containing receptor objects. rods and cones in addition to layers of Farsightedness: A other neurons condition in which (bipolar, ganglion faraway objects are seen cells) that process more clearly than near visual information. objects.
49 50
Optic Nerve, Blind Spot & Fovea Test your Blind Spot
Optic nerve: Carries neural impulses from the eye to the brain. Use your textbook. Close your left eye, and fixate your Blind Spot: Point where the optic nerve leaves the eye because right eye on the black dot. Move the page towards your there are no receptor cells located there. This creates a blind spot. Fovea: Central point in the retina around which the eye’s eye and away from your eye. At some point the car on cones cluster. the right will disappear due to a blind spot.
http://www.bergen.org 51 52
Photoreceptors Bipolar & Ganglion Cells
Bipolar cells receive messages from photoreceptors and transmit them to ganglion cells, which are for the optic nerve.
E.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969
53 54
9 Visual Information Processing Ganglion & Thalamic Cells
Optic nerves connect to the thalamus in the middle of Retinal ganglion cells and thalamic neurons break the brain, and the thalamus connects to the visual down visual stimuli into small components and have cortex. receptive fields with center-surround organization.
ON-center OFF-Surround
Action Potentials 55 56
Feature Detection Shape Detection
Nerve cells in the visual cortex respond to specific Specific combinations of temporal lobe activity occur features, such as edges, angles, and movement. as people look at shoes, faces, chairs and houses. Ross Kinnaird/ Allsport/ Getty Images Images Getty Allsport/ Ross Kinnaird/ Ishai, Ungerleider, Martin and Haxby/ NIMH Haxby/ and Martin Ungerleider, Ishai, 57 58
Theories of Color Vision Subtraction of Colors
Trichromatic theory: Based on behavioral experiments, Helmholtz suggested that the retina should contain three receptors that are sensitive to red, If three primary colors blue and green colors. (pigments) are mixed, subtraction of all Standard stimulus wavelengths occurs and the color black is the Comparison stimulus result.
Max Medium Low
Blue Green Red 59 60
10 Addition of Colors Photoreceptors: Trichromatic Theory
Blue Green Red If three primary colors (lights) are mixed, the Cones Cones Cones wavelengths are added and the color white is the result. MacNichol, Wald and Brown (1967) measured directly the Fritz LIFE Goro, magazine, © 1971 Time Warner, Inc. absorption spectra of visual pigments of single cones obtained from the retinas of humans. Short Medium Long wave wave wave 61 62
Opponent Process Theory Color Blindness
Hering proposed that we process four primary Genetic disorder in which people are blind to green or colors combined in pairs of red-green, blue-yellow, red colors. This supports the Trichromatic theory. and black-white.
Cones
Retinal Ganglion Cells 63 Ishihara Test 64
Opponent Colors Perception in Brain
Our perceptions are a combination of sensory (bottom-up) and cognitive (top-down) processes.
Gaze at the middle of the flag for about 30 Seconds. When it disappears, stare at the dot and report
whether or not you see Britain's flag. 65 66
11 Visual Information Processing From Sensation to Recognition
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 and movement etc.
67 68 Tim Bieber/ The Image Bank Bank Image The Bieber/ Tim
Color Constancy Change Blindness
Color of an object remains the same under different • Phenomenon that occurs when a person viewing a visual illuminations. However, when context changes the scene apparently fails to detect color of an object may look different. large changes in the scene. • The change typically has to coincide with some visual
R. Beau Lotto at University College, London disruption (saccade: eye movement) or a brief obscuration of the observed scene or image. • Memory (short term) may be involved.
http://www.youtube.com/watch?v=0grANlx7y2E
69 70 McConkie & Currie (1996) http://nivea.psycho.univ-paris5.fr/ECS/ECS-CB.html
Visual Illusions
• http://www.michaelbach.de/ot/
More on this in next Audition lecture….
71 72
12 The Stimulus Input: Sound Waves Sound Characteristics
Sound waves are composed of compression (more Physical (psychological) dense) and rarefaction (less dense) of air molecules. . Frequency (pitch) . Intensity (loudness) . Quality (timbre)
Acoustical transduction: Conversion of sound waves into neural impulses in the hair cells of the inner ear.
73 74
Frequency (Pitch) Intensity (Loudness)
Frequency (pitch): The dimension of Intensity (Loudness): frequency Amount of energy in determined by the a wave, determined wavelength of by the amplitude, sound. relates to the perceived loudness. Wavelength: The distance from the peak of one wave to the peak of the next.
75 76
Loudness of Sound Quality (Timbre)
Quality (Timbre): Characteristics of sound from a Richard Kaylin/ Stone/ Getty Images zither and a guitar allows the ear to distinguish between the two. www.jamesjonesinstruments.com
120dB http://www.1christian.net
Zither 70dB 77 78 Guitar
13 Overtones The Ear
Overtones: Makes the distinction among musical Dr. Fred Hossler/ Visuals Unlimited instruments possible.
79 80
The Ear Cochlea
Outer Ear: Pinna. Collects sounds. Cochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to auditory Middle Ear: Chamber between eardrum and signals. 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. 81 82
Theories of Audition Theories of Audition
Place Theory suggests that sound frequencies Frequency Theory states that the rate of nerve impulses stimulate the basilar membrane at specific places traveling up the auditory nerve matches the frequency resulting in perceived pitch. of a tone, thus enabling us to sense its pitch.
Can not explain low frequencies Sound Auditory Nerve Action Potentials
http://www.pc.rhul.ac.uk Frequency 200100 Hz
Can not explain high frequencies 83 84
14 Localization of Sounds Localization of Sound
Because we have two ears, sounds that reach one ear 1. Intensity differences faster than the other ear cause us to localize the sound. 2. Time differences
Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as a “shadow” or partial sound barrier.
85 86
Hearing Loss Hearing Deficits
Conduction Hearing Loss: Hearing loss caused by Older people tend to hear low frequencies well but suffer damage to the mechanical system that conducts sound hearing loss when listening for high frequencies. waves to the cochlea.
Sensorineural Hearing Loss: Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve, also called nerve deafness.
87 88
Deaf Culture
Cochlear implants are electronic devices that enable the brain to hear sounds. Scientist, Wolfgang Gstottner. (2004) Vol. 92, Number 5. (p. 437) EG Images/ J.S. Wilson © American
89 Deaf Musician Cochlear Implant 90
15 Pain Pain 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. (CIPA: Congenital Insensitivity to Pain)
PAIN AP Photo/ Stephen Morton
91 Ashley Blocker (right) feels neither pain 92 nor extreme hot or cold.
Biopsychosocial Influences Gate-Control Theory
Melzak and Wall (1965, 1983) proposed that our spinal cord contains neurological “gates” that either block pain or allow it to be sensed. Gary Comer/ PhototakeUSA.com
93 94
Pain Control Body Position and Movement
Pain can be controlled by a number of therapies The sense of our body parts’ position and movement is including, drugs, surgery, acupuncture, exercise, called kinesthesis. The vestibular sense monitors the hypnosis, and even thought distraction. head (and body’s) position. http://www.heyokamagazine.com Bob Daemmrich/ The Image Works ©Hunter Hoffman, www.vrpain.com Todd Richards and Aric Vills, U.W.
95 Whirling Dervishes Wire Walk 96
16