Chapter 4, Period 7



Chapter 4: Sensation and Perception



Vocabulary

1. Perception--process of selecting, organizing, and interpreting sensory information
2. Sensation--process of receiving, converting, and transmitting raw sensory information from the external and internal environments to the brain
Understanding Sensation
3. Absolute Threshold--smallest amount of a stimulus needed to detect that the stimulus is present
4. Coding--process that converts a particular sensory input into a specific sensation
5. Difference Threshold--minimal difference needed to notice a stimulus change; also call the “just noticeable difference” (JND)
6. Gate-Control Theory of Pain--theory that pain sensations are processed and altered by mechanisms within the spinal cord
7. Psychophysics-- study of the relation between attributes of the physical world and our psychological experience of them
8. Sensory Adaptation--repeated or constant stimulation decreases the number of sensory messages sent to the brain, which causes decreased sensation
9. Sensory Reduction--filtering and analyzing incoming sensations before sending a
neural message to the cortex
10. Subliminal Perception (Messages)-- (literally “below the threshold”) this type of stimuli demonstrates that information processing does occur even when we are not aware of it
11. Synesthesia--a mixing of sensory experiences (e.g., “seeing” color when a sound is heard)
12. Transduction--converting a stimulus to a receptor into neural impulses
13. Weber’s Law—this law states that the change in a stimulus that will be just noticeable is a constant ratio of the original stimulus
How We See and Hear
14. Accommodation- The automatic adjustment of the eye, which occurs when muscles change the shape of the lens so that it focuses light on the retina from objects at different distances.
15. Amplitude- The height of a light or sound wave (pertaining to light, it refers to brightness, in pertaining to sound, it refers to loudness).
16. Audition- The sense of hearing.
17. Blind Spot- an area near the fovea that has no visual receptors at all and absolutely no vision, this aptly named “blind spot” is where blood vessels and nerve pathways enter and exit the eyeball.
18. Cochlea- Three chambered, snail-shaped structure in inner ear containing the receptors for hearing. (The receptors for hearing are in the basilar membrane, these are known as hair cells.) (The path that sound travels to be heard is as follows: Pinna-auditory canal-eardrum or tympanic membrane- the ossicles: malleus, incus, stapes- oval window-cochlea- basilar membrane- hair cells- auditory nerve- brain.)
19. Conduction Deafness- Middle-ear deafness resulting from problems with transferring sound waves to the inner ear.
20. Cones- Receptor cells, concentrated near the center of the retina, responsible for color vision and fine detail; most sensitive in rightly lit conditions.
21. Farsightedness (Hyperopia)- Visual acuity problem resulting from the cornea and lens focusing an image behind the retina.
22. Fovea- A tiny pit in the center of the retina filled wit cones and responsible for sharp vision.
23. Frequency-How often a light or sound wave cycles, or the number of complete wavelengths that pass a point in a given time.
24. Frequency Theory- Explains how we hear lower-pitched sounds; hair cells in the basilar membrane bend and fire neural messages (action potentials) at the same rate as the sound frequency
25. Nearsightedness (myopia)- Visual acuity problem resulting from cornea and lens focusing an image in front of the retina
26. Nerve Deafness- Inner-ear deafness resulting from damage to the cochlea, hair cells, or auditory nerve
27. Place Theory- Explains how we hear higher-pitched sounds; different high-pitched sounds bend the basilar membrane hair cells at different locations in the cochlea
28. Retina- Light-sensitive inner surface of the back of the eye, which contains the receptor cells for vision (rods and cones)
29. Rods- Receptor cells in the retina that detect shades of gray and are responsible for peripheral vision and are most sensitive in dim light
30. Wavelength- Distance between the crests (or peaks) of light or sound waves; the shorter the wavelength, the higher the frequency
Our Other Senses
31. Gustation- Sense of taste; the five different types of taste are: sweet, sour, salty, bitter and umami (or savory)
32. Kinesthesia- Sensory system for body posture and orientation
33. Lock and Key Theory-the theory that each odorous chemical excites a specific portion of the olfactory bulb, and each odor is then coded and detected according to the stimulated area (in other words, odors only affect olfactory receptors that have the correct shape for that particular molecule, in the same way that a key has to have the shape to fit the lock)
34. Olfaction- Sense of smell
35. Pheromones- Airborne chemicals that affect behavior, including recognition if family members, aggression, territorial marking, and mating.
Understanding Perception
36. Afterimage effect- optical illusions that refer to an image continuing to appear in one's vision after the exposure to the original image has ceased, one of the most common afterimages is the bright glow that seems to float before one's eyes after looking into a light source for a few seconds
37. Binocular Cues- Visual input from two eyes that allows perception of depth or distance.
38. Bottom-Up Processing- Information on processing that begins “at the bottom” with raw sensory data that “feed up” to the brain.
39. Cocktail-Party Phenomenon- the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations, this is also what allows us to hear our name over all other background noises
40. Convergence- Binocular depth cue in which the closer the object, the more the eye converges, or turns in.
41. Depth Perception- The ability to perceive a 3-D space and to accurately judge distance.
42. Extrasensory Perception- Perceptual, or “psychic”, abilities that supposedly go beyond the known senses
43. Feature Detectors- Specialized neurons that respond only to important sensory information.
44. Gestalt Principles of Organization—these laws of perceptual organization are only valid for people who have been schooled in geometrical concepts, they specify how people perceive form
-Figure-Ground-the ground is always seen as further away than the figure
-Proximity- objects that are physically close together are grounded together
-Continuity- objects that continue a pattern are grouped together
-Closure- the tendency to see a finished unit from an incomplete stimulus
-Similarity- Similar objects are grounded together
45. Habituation- Tendency of the brain to ignore environmental factors that remain constant.
46. Illusion- False or misleading perceptions
47. Monocular Cues- Visual input from a single eye alone that contributes to perception of a depth or distance.
48. Opponent-Process Theory- Hering’s theory that color perception is based on three systems of color opposites: blue-yellow, red-green, and black-white.
49. Perceptual Constancy- Tendency for the environment to be perceived as remaining the same even with changes in sensory input.
Perceptual Constancies
1. Size Constancy- the perceived size of an object remains the same even though the size of its retinal images changes
2. Shape Constancy- occurs when your brain remembers past experiences with objects that only seemed to change shape as you moved but actually remained constant
3.4. Color and Brightness constancy- these enable us to perceive things as retaining the same color or brightness levels even though the amount of light may vary
50. Perceptual Set- Readiness to perceive in a particular manner based on expectation.
51. Retinal Disparity- Binocular cue to distance where he separation of the eyes causes different images to fall on each retina.
52. Selective Attention- Filtering out and attending only to important sensory messages.
53. Subliminal- Pertaining to any stimulus presented below the threshold of conscious awareness.
54. Top-Down Processing- Information processing that starts “at the top,” with the observer’s thoughts, expectations, and knowledge, and works down.
55. Trichromatic Theory- Young’s theory that color perception results from mixing three distinct color systems- red, green, and blue.

Chapter Outline
I. Sensation and Perception
A. Sensation and Perception are very similar and can overlap
1. Sensation-process of receiving, converting, and transmitting raw sensory info from external/internal environments to the brain
2. Perception- process of selecting, organizing, and interpreting sensory information
B. Understanding Sensation
1. Basic operations of sensation
i. How we see and hear
ii. Other senses used
2. Five Basic senses
i. Vision, hearing, taste, smell, and touch
3. Other Senses
i. Vestibular
ii. Kinesthesia
4. Understanding Perception
i. How one selects, organizes, and interprets information from senses
a. Paying attention
b. Perceive distances
c. Different colors
5. Research Highlight
i. Sublimal perception
ii. Extrasensory Perception (ESP)
II. Understanding Sensations
A. Synesthesia
1. Mixing of senses
B. Non-blending sensations
1. External and internal environments
III. Processing: Getting the Outside Inside
A. Receptors of Sense
1. Transduction
B. Filtering of Stimuli
1. Prevent brain from overwhelming
2. Custom design senses
3. Sensory reduction
i. Reticular information
C. Differentiating Sensations
1. Activation of stimulated nerve
i. Coding
2. Different travel routes
IV. Thresholds: Testing our Sensitivity
A. Psychophysics
1. How physical stimuli are related psychologically
2. Studies strength of stimulus
i. Absolute threshold
ii. Difference Threshold
V. Adaptation: Weakening our Sensitivity
A. Sensory Adaptation
1.Stimulus presented over a length of time
i. Sensation fades/adjusts
ii. Receptors tire out
2. Evolution
i. Tunes out repetitive, non-important information
ii. Pays attention to change
3. Some senses adapt quickly
i. Smell and touch
ii. Not for vision because its constantly moving
4. Survival
B. Endorphins/Pain Control
1. Inhibits pain perception
2. Acupuncture
C. Gate-Control Theory
1. Ronald Melzack and Patrick Wall (1965)
2. Blocking/sending of messages
i. Brain signals
ii. Pressure messages
D. Imagined Pain
1. Focusing on pain can intensify it
2. Faulty messages
E. Chemically Controlled
1. Brain is capable of generating pain and others sensations
i. Ringing in ears (tinnitus)
ii. Phantom pain
iii. Conflicting messages
VI. How We See and Hear
1. Aunt improvised doll for Helen Keller, she still remembered importance of having eyes.
A. Vision: The Eyes Have It
1. Waves of Light
i. Vision is based upon wave phenomena; consider ocean waves
a. Waves have a certain distance between them called wavelength; this determines the hue (color) we see
b. The number of passing waves in a set amount of time is called the frequency; this determines the color also
c. The characteristic of height is technically called amplitude; this determines the brightness of the light we see
ii. Light is waves of electromagnetic energy of a certain wavelength; there are many different types of these waves
a. Only the visible spectrum part of the electromagnetic spectrum can be detected by our visual receptors
iii. The purity or complexity (mix) of light waves determines whether we see one color or one that is a mix of different colors
2. Cornea, Iris, Pupil, and Lens
i. Light enters cornea first; a protective, transparent tissue that helps focus light rays
ii. Iris is behind cornea; provides the color of eye
iii. Muscles in iris allow pupil to dilate/constrict in response to light intensity (inner emotions also)
iv. Lens is behind iris; adds to the focusing begun by cornea; is adjustable
v. Accommodation allows for focus on objects either close or far away, caused by the muscles in the lens (far-thins and flattens, near- thickens and curves)
vi. Nearsightedness (myopia)- eye deeper than normal, causes light rays to be focused in front of retina and image is blurred
vii. Farsightedness (hyperopia)- eye shorter than normal, light focused on point beyond retina, inability to focus at close range
viii. Presbyopia- lenses start to lose elasticity and ability to accommodate for near vision
a. Near/Farsightedness easily remedied with corrective lenses, laser surgery
3. Retina
i. An area at back of eye that contains blood vessels and network of neurons that transmit neural info to occipital lobes, contains light sensitive cells called rods and cones
ii. Rods- more numerous, more sensitive to light, enable vision in dim light at the expense of fine detail and color
iii. Cones- better in bright light, fine detail and color, sensitive to many wavelengths but each is maximally sensitive to one color
iv. Cones are more numerous towards center of retina; location of fovea- tiny pit filled with cones, responsible for sharpest vision
v. Near fovea is “blind spot” with no visual receptors and no vision, where blood vessels and nerve pathways enter/exit eyeball
a. Momentary blindness: dark adaptation-second or two before rods a functional enough to see, 20-30 min until max light sensitivity reached: light adaptation-7-10 min, work of cones, as we age, these adaptations takes longer
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"The Expert Opinion: Are You A Good Candidate For Premium Intraocular Lenses For Cataract Surgery?" Baltimore Eye Care. Web. 16 Feb. 2011. <http://www.baltimore-eyecare.com/the-expert opinion/2009/03/are-you-good-candidate-for-premium.html>.

B. Hearing: A Sound Sensation
i. Helen Keller, “deafness cuts people off from people.”
ii. Audition- the sense of hearing
2. Waves of Sound
i. As a physical phenomenon, based upon pressure waves in air
ii. Frequency determines pitch, amplitude determines loudness, complexity determines timbre- what allows us to distinguish between note on two different instruments or between human voices
iii. Sound could be a pure tone of single frequency or a complex mix of frequencies and amplitudes
3. Ear Anatomy and Function
i. Outer ear gathers and delivers sound waves to middle ear, which amplifies and concentrates, the inner ear contains receptor cells that transduce mechanical energy of sound waves into neural impulses
(In order of path sound would travel)
ii. Pinna- gathers sound waves and funnels into outer ear, the part of ear visible
iii. Auditory canal- a tube like structure that focuses the sound
iv. Eardrum or tympanic membrane-at end of auditory canal, thin and tautly stretched membrane, vibrates as sound hits it
v. The ossicles- made up of malleus (hammer), incus (anvil, and stapes (stirrup), vibration causes these three bones to vibrate
vi. Oval window- stapes bone presses on this membrane causing it to vibrate
vii. Cochlea- vibration of oval window creates waves in the fluid that fills, a snail shaped structure that contains basilar membrane with receptors for hearing
viii. Hair cells- the hearing receptors that bend from side to side, at this point mechanical waves turn into electrochemical impulses that are carried by auditory nerve to brain
a. We hear different pitch (low to high) and loudness (soft to loud) depending on frequency and intensity
ix. Place theory- we hear high pitched sounds corresponding to the place along the basilar membrane that is most stimulated, different hairs at different locations in cochlea
x. Frequency theory- low pitched sound causes hair cells along the basilar membrane to bend and fire neural messages (action potentials) at the same rate as the frequency of that sound
xi. Conduction deafness- middle ear deafness, results from problems with mechanical system that conducts sound waves to inner ear
a. Nerve deafness- inner ear deafness, involves damage to cochlea, hair cells, or auditory nerve
b. Damage to nerve or receptor cells almost always permanent, only current treatment for nerve deaf. is small electronic device called cochlear implant which produces only crude approximation of hearing
1. Pay attention to bodily warnings, often first signs of hearing loss; changes in normal hearing threshold or tinnitus- a whistling or ringing sensation in ears

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"Human Brain Structure | TutorVista." Tutorvista.com - Online Tutoring, Homework Help for Math, Science, English from Best Online Tutor. Web. 16 Feb. 2011. <http://www.tutorvista.com/topic/human-brain-structure>.
VII. Our Other Senses
A. Taste, smell and body sense are important to our perception
B. Smell and Taste: Sensing Chemicals
1. chemical senses-ex. taste and smell
2. chemoreceptors- these chemical senses are triggered by particular chemical molecules
3. Olfaction- smelling; extremely sensative
i. ex. can smell something before we see it
ii. the blind learn to recognize a particular persons distinct scent
iii. olfactory epithelium-receptor cells in the nose; coated with mucus
iv. olfactory bulb-below frontal lobe; chemical molecules travel to here
v. pheromones- chemical odors
4. Gustation- tasting; not vital
i. to differentiate from harmful substances
ii. sensations: sweet, sour, salty, bitter and umami-new; sensitive to protein
iii. glutamate- what umami is sensitive to; contributes to natural foods, fish and cheese
iv. taste buds-respond to taste; located on papillae (bumps; on tongue, palate and back of mouth)
v. taste buds constantly dying and being replenished, slows as we age
C. The Body Senses: More Than Just Touch
1. body senses-tell the brain about the body-orientation, movement, touching
i. include skin senses, vestibular sense, and kinesthesia
2. The Skin Senses-extremely important
i. ex. if you put your hand on a burner, the nerve endings signal the brain
ii. skin sensations: pressure, temperature and pain
3. The Vestibular Sense-body position and orientation in space
i. consists of vestibular sacs and semicircular canals in the inner ear
ii. semicircular canals-information regarding balance
iii. vestibular sacs-sensitive to angle of head
iv. ex. by traveling on an extremely windy road, vestibular sense can become confused by the strange feeling
4. Kinesthesia-posture and orientation
i. sensors throughout the body
ii. muscles, joins and tendons
VIII. Understanding Perception
A. sense before perceive
B. Illusion-distorted images
C. Selection: Extracting Important Messages
1. selection-determining where to put our attention
2. Selective Attention-filtering extra messages out
i. ex. reading a book in a house where there are many noises, a car alarm going off outside, a faucet running and a child asking a mother for help, and being able to focus only on understanding a reading of the book.
3. Feature Detectors (or feature analyzers) neurons that respond to some types of sensory information
i. prosopagnosia-failure to recognize face
ii. ex. kittens raised with only vertical (or horizontal) stripped walls suffered impairments
4. Habituation-ignoring constant factors
i. occurs in brain; sensory adaptation occurs in sensory receptors
ii. intrigued by stimuli which are: intense, novel, moving, contrasting, and repitious
D. Organization: Form, Constancy, Depth, and Color
1. must organize information to make sense of the world
2. Form Perception
i. principle of form organization- learning to understand perceptual principles
ii. gestalt- pattern; to perceive a whole stimuli
iii. fundamental Gestalt principle- figure and ground, ex. seeing words on page, black and white
iv. reversible figure- which is ground and which is figure issue
E. Gender & Cultural Diversity
1. Gestalt Principles
i. Valid only for people schooled in geometrical concept.
ii. Experience with pictures is necessary or interpreting 2D figures and 3D forms
a. figure-ground: the ground is always seen as farther away than the figure
b. proximity: objects that are physically close together are grouped together
c. continuity: objects that continue a pattern are grouped together.
d. closure: the tendency to see a finished unit from an incomplete stimulus
e. similarity: similar objects are grouped together
F. Perceptual Constancies: tendency for the environment to be perceived as remaining the same even with changes in sensory input.
1. size constancy
i. the perceived size of an object remain the same even though the size of its retinal image changes
2. shape constancy
i. your brain remembers past experiences with objects that only seemed to change shape as you moved but actually remained constant.
ex. of shape constancy: the Ames room illusion
Ames_Room2.jpg




"Ames Room." SmilePanic. Web. 16 Feb. 2011. <http://smilepanic.com/ames-room>.

3. color constancy and brightness constancy
i. if you know an object from prior experience, you expect it will be the same color and the same relative brightness in bright light as in low light.
G. Depth Perception: the ability to perceive 3D space and to accurately judge distance
1.It is inborn and primarily learned (nature-nurture debate)
2. How do we perceive a 3D world with a 2D receptor system?
i. binocular cues: visual input from two eyes that allows perception of depth or distance
a. retinal disparity: binocular cue to distance where the separation of the eyes causes different images to fall on each retina
b. stereoscopic vision: brain fuses different images received by our yes into one overall image
c. convergence: binocular depth cues in which the closer the object, the more eyes converge, or turn inward
i. monocular cues: visual input from a single eye alone that contributes to perception of depth or distance
a. accommodation: the changes in the shape of the lens of the eye in response to the distance of the object on which you are focusing.
b. motion parallax: when an observer is moving, objects at various distances move at different speeds across the retinal field
H. Color Perception
1. Research suggests that color perception is culturally universal; we all seem to see essentially the same colored world.
2. How do we perceive color?
i. Trichromatic theory: First proposed by Thomas Young in early 1800’s, but refined by Hermann von Helmholtz. Proposes that color perception results from mixing of the “three color systems”, each system is sensitive to one of the three colors: red, green, or blue. The mixing of lights yields the full spectrum of colors.
ii. Trichromatic Theory’s Major Flaws
a. Doesn’t explain defects in color vision (color blindness)
b. Does not explain color aftereffects.
iii. Opponent-Process Theory: Proposed by Ewald Hering in late 1800’s. Proposes the three-color systems, but suggests that each system is sensitive to opposing colors; blue-yellow, red-green, and black-white. Explains color vision defects.
3. Which theory is correct?
i. Both theories are correct. In 1964, George Wald demonstrated that there are three different types of cones in the retina, and in 1965, R.L. DeValois discovered cells that respond to color in an opponent fashion.
IX. Interpretation: The final stage of perception, where the brain uses sensory information to explain and make judgments about the external world.
A. Perceptual Adaptation: The ability the brain has to adjust to a distorted world.
1. George Stratton in 1897 preformed a study in which he wore special lenses that distorted his perpetual environment. On the third day of wearing the lenses, his perceptions were back to normal. This proved that we can adjust, and that the brain is retrained to create a newly coherent and familiar world.
B. Perceptual Set: Mental dispositions where our previous experiences influence how we interpret and perceive the world. A person's past experiences would dictate whether or not they saw faces or a cup.
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"MYTCCPSY." Individual Faculty Homepages. Web. 16 Feb. 2011. <http://faculty.tcc.fl.edu/hss/mcguffr/>.
C. Frame of Reference: Perceptions of people, objects, or situations are altered depending on the frame of reference, or context.
D. Bottom-up or Top-down processing: Sensory information is received and worked to perceptual in one of two processes.
1. Bottom-up processing: Information is taken in through the sensory receptors, and then is sent “up” to the brain for analysis.
2. Top-down processing: Processes begin with thoughts, expectations, and higher learning and are broken “down” to sensory level of the eyes, ears, nose, and tongue.15 Devices to Help Remember Important Terms
1. Sensory Adaptation: Ignoring the parents
Stage 1: Mom has been nagging you to clean up your room- Repetitive Info.
Stage2: Whenever mom brings up cleaning your room, you tune out and think about your weekend- Evolution/Ignoring.
Stage 3: While Mom is telling you to clean your room, she says that you can have the car- Start listening to Mom due to change of topic.
2. Sensation vs. Perception
Sensation- Sensing the world around you by taking in all that comes to you; first impression of friend
Perception- processing the information that has come to you and organizing it so you can understand; forming a relationship and getting to know your friend
3. Vestibular vs. Kinesthesia
Vestibular- Completing a handstand needs the vestibular sense. If your vestibular senses were not working, you would not know if you were upside-down or right-side-up.=Balance
Kinesthesia- tells you were your body parts are in relation to your head: You have to know where your head is in from your hands tin order to touch the tip of your finger to your nose with your eyes closed.
4. Path of Light to Brain
Cornea, Iris, Pupil, Lens, Retina, Occipital lobe
Cussing Isn’t Proper Ladies, Real [words] Only
5. Path of Sound Wave
Pinna, Auditory canal, Eardrum, Malleus, Incus, Stapes, Oval window, Cochlea, Basilar membrane, Hair cells
Pencil And Eraser Make Improper Spelling On Charts [a] Bad Habit
6. Way to Remember all Five Tastes
Sweet, Sour, Salty, Bitter, Umami
She Sells Seashells By Unicycles
7. Selective Attention
Exp. reading a book in a house where there are many noises, a car alarm going off outside, a faucet running and a child asking a mother for help, and being able to focus only on understanding a reading of the book.
8. Feature Detectors.
Exp. kittens raised with only vertical (or horizontal) stripped walls suffered impairments
9. Olfaction
Exp. can smell something before we see it
10.Gestalt principles:
Comprehending Sensation & Perception Can [be] Fun!
Continuity, Similarity, Proximity, Closeness, Figure-Ground
11.Perceptual Constancies
Cute Bunnies Sing Songs
Color Constancy, Brightness Constancy, Size Constancy, Shape Constancy
12. Depth Perception-two cues: binocular and monocular
Binocular: Bino the Dino needs both eyes to use his Binoculars.
Monocular: Mono the Monkey runs into walls because he can only see through one eye.
13. Trichromatic Theory
Ronald Grows Blueberries
Red, Green, Blue
14. Opponent Process Theory:
Opposites attract!- Blueberries-Yams, Radishes-Grapefruit, Boy-Woman!
Blue-Yellow, Red-Green, Black-White
15. Bottom-up processing:
Barney sees the letters and forms them into words with bottom up processing!

Important People
Robert F Valois- Studied electrophysical recording of cells in the optic nerve and optic pathways to the brain. Discovered cells that respond to color in an opponent fashion in the thalamus. Shows that both of the color theories are true: color is processed in a trichromatic fashion at the level of the retina (cones) and in an opponent fashion at the level of the optic nerve and the thalamus (in the brain).
M.C. Escher (149)- Worked on Depth Perception (the ability to perceive three dimensional space and to accurately judge distance). Especially with infants and toddlers, she proved depth perception by the experiment visual cliff. Where an infant is placed on a platform simulating a steep cliff, and stays away from the “deep” or “cliff-like” area of the platform. Some criticism of this experiment is that by the time infants are old enough to be tested, they have been crawling, and therefore have learned to perceive depth.
Elanor Gibson (155)- Worked on Depth Perception (the ability to perceive three dimensional space and to accurately judge distance). Especially with infants and toddlers, she proved depth perception by the experiment visual cliff. Where an infant is placed on a platform simulating a steep cliff, and stays away from the “deep” or “cliff-like” area of the platform. Some criticism of this experiment is that by the time infants are old enough to be tested, they have been crawling, and therefore have learned to perceive depth.
R.L. Gregory (156)- Monocular cues. “We are effectively one-eyed for distances greater than perhaps 100 meters.” Means that retinal disparity and convergence are inadequate in judging distances longer than a football field. We have several monocular cues available separately to each eye.
Hermann von Helmholtz (158)- Elaborated on and refined the trichromatic theory late in the nineteenth century. Accomplished this by identifying the three variables that are used to characterize a color. Theory has two major flaws: doesn’t explain defects in color vision and doesn’t explain color aftereffects.
Ewald Hering (158)- Opponent-process theory. Proposed three color systems, each sensitive to two opposing colors--blue and yellow, rend and green, black and white. This theory explains color vision defects. Proven correct as well as trichromatic theory by George Wald and R.L. Devalois, respectively.
Hubel and Weisel (147)- Feature detectors (specialized neurons that respond only to certain sensory information). Found feature detectors in cats that respond to specific lines and angles. Inspired similar studies with humans that have found feature detectors in the temporal and occipital lobes that respond maximally to faces.
Ronald Melzack and Patrick Wall (134)-proposed the gate-control theory in 1965. The theory suggests that the experience of pain depends partly on whether the neural message gets past a “gatekeeper” in the spinal cord. It is then the “gatekeepers” job to either block or allow pain signals to pass on into the brain.
Allen Souchek (155)- Depth perception. More accuracy of vision if looking directly at an object as depth perception is better than looking out the corner of your eye. An example of this is being thrown a ball and looking directly at it, to judge the distance and becoming more accurate in catching the ball.
George Stratton (159)- Perceptual adaptation. Tested the adaptability of vision to a distorted world by wearing special lenses for eight days. After a few days he almost completely adjusted, his expectations of how the world should be arranged had changed. Proving we have the ability to adapt our perceptions by retraining our brains.
George Wald- In 1964, Wald demonstrated that there are three types of cones in the retina, each with its own type of photopigment. One type of pigment is sensitive to blue light, one is sensitive to green light, and the third is sensitive to red light. This finding helped prove the validity of the Trichomatic Theory (Thomas Young).
Ernst Weber- In working with auditory senses, Weber established that in order to survive, organisms must have difference thresholds low enough to detect minute changes in important stimuli. This became known as the just noticeable difference (jnd) or the difference threshold. According the Weber’s Law, difference thresholds increase in proportion to the size of the stimulus.
Wilhelm Wundt- Wundt is most commonly known as the father of “experimental psychology”. He created the first psychology lab to study the elements of the conscious experience including sensation and perception, memory, attention, emotion, cognition, learning and language. He believed the psychology dealt with conscious experiences and focused on introspection, monitoring and reporting on the contents of consciousness: one’s thoughts, feelings, and sensory experiences.
Thomas Young (158)- First proposed in early nineteenth century, the trichromatic theory, which originates from the Greek words of “three colors”. Theory that color perception results from mixing three distinct colors of red, green, and blue. Went on to demonstrate that by mixing these three colors together, one will being able to use and see the full spectrum of colors perceived.

Interesting Facts
You Tube Videos:
Earwax:
• Earwax is used to clean and protect the ear canal from debris and provides natural waterproofing.
• According to the University of Mary Washington, cerumen glands located in the outer portion of the ear canal secrete cerumen, a sticky and waxy fluid, into the external auditory canal to protect and waterproof the delicate lining. When this secretion is combined with sweat, sebum and the keratin from dead skin cells, it produces earwax. According to Harvard Medical School, earwax has antibacterial and antifungal properties. Genetics will determine if you have a wet wax secretion or a dry wax secretion. Those of European decent will generally have cerumen that is 50 percent fat, making a wet wax. Those of Asian decent will normally have only 20 percent fat making it dry.
• If earwax builds up, it can cause loss of hearing, earaches and infections. Your body will normally remove wax on its own. The movement of your jaw actually causes waves in the canal, which help to push out earwax and debris. If you do get a wax build-up, you can soften it by adding a few drops of olive oil in each ear every few weeks and letting it naturally fall out (http://www.livestrong.com/article/257571-what-makes-wax-in-an-ear/#ixzz1I8On3OiR).
Opponent-Process Theory Facts:
  • World War II, colorblind men were sent on special missions, because their decreased ability to see green led to an increased ability to see through or detect camouflage.
  • Bulls are actually colorblind; it is the motion of a red cape, which angers them, not the color itself (http://tjshome.com/colorblind.php)
Vision: