1. Myers’ PSYCHOLOGY
Chapter 5
Sensation
Complete 5.1 prior to beginning

2. Sensation and Perception
a process by which our sensory receptors and nervous system receive and interpret stimulus energy
After receiving sensory information we must process it and this is perception
Perception
a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
Sensation and perception blend into one continuous process
5.2 Top Picture—to show the difference between sensation and perception. Looks like a meaningless blotch, students will try to figure it out—stimulation/sensation is being received but not perceived. The subject is a dog, and only part of a dog. Students will probably try to see the whole dog; you cannot tell figure from ground
5.2 Bottom picture—Fraser Spiral—it looks like a spiral but is actually a set of concentric circles

3. Sensation Bottom-Up Processing Top-Down Processing
analysis that begins with the sense receptors and works up to the brain’s integration of sensory information
Detects lines, angles, and colors
Top-Down Processing
information processing guided by higher-level mental processes
as when we construct perceptions drawing on our experience and expectations
Information not form our senses, knowledge based
Interpretation
Top Down is the involvement of the brain in making meaning out of stimuli. For example there are people who can see everything clearly (sensation) but cannot recognize even their own faces (perception).
Placing meaning to sensations and stimuli is the act of perception

4. The Forest Has Eyes
Our sensory and perceptual processes work together to help us sort out complex processes
Bottom-up is the colors, lines, angles of the horses, rider and sourroundings
Top-down is the title of the painting and what will give the painting meaning
The Forest Has Eyes is the title of this work---in studying it we look at the expressions on the faces, there is something foreboding about this picture, and after we have read the title we notice other things…

5. Sensation and Perception Cycle

6. Thresholds We live in a world on constant stimuli
What do we notice and not notice?
What do we feel and not feel?
What do we sense and perceive?
Psychophysics if the study of how physical energy relates to our psychological experience
What stimuli can we detect?
At what intensity?
How sensitive are we to changing stimulation

7. Psychophysics Psychophysics
study of the relationship between physical characteristics of stimuli and our psychological experience of them
Light- brightness
Sound- volume
Pressure- weight
Taste- sweetness

8. Sensation- Thresholds
Absolute Threshold
What we are super-sensitive too, even if the stimuli is faint
Eyelash on our face is one example
Absolute threshold is the minimum stimulation needed to detect a particular stimulus 50% of the time
Three methods to test
Method of Limits: begin with a minimal stimulus and increase until it is perceived by subject
Method of right and wrong cases: subject sees identical stimuli repeatedly and says yes if perceives them or it they are different, and no if not perceived or the two are not different—informs how likely it is that any given stimulus level or difference between stimuli will be perceived by subject.
Method of adjustment—adjust a comparison stimulus until it appears to be identical to the standard stimulus, errors occur and are noted then averaged to give a measure of jnd
Try the timer in the kitchen—put it in a quiet room, move away and then move back—the point at which the ticking is perceived is the absolute threshold, at that point they may be able to hear sometimes and others time not, needing to move a few feet one way or the other—lapses of attention, fatigue other factors influence

9. Signal Detection Theory
Detecting a weak stimuli depends on the signal’s strength but also on a psychological state
predicts how and when we detect a weak stimulus signal
Measured as ratio of “hits” to “false alarms”
Why do people respond differently to same stimuli
Why does same person’s reactions vary by circumstances?
Why parents hear the slightest sound fro their baby, but miss louder sounds from other sources
Detection depends partly on person’s
experience
expectations
motivation
level of fatigue

10. Subliminal! We have all heard of this
Subliminal messages can be both visual and auditory
Subliminal means stimuli below our threshold that we unconsciously detect and perceive
Remember that absolute threshold is 50% of the time – so yes we can be and are stimulated by things below that threshold
Can we feel what we do not know and cannot describe?
Can we be manipulated using this?
Psychologists say NO!
When it appears that they do is it placebo effect?

11. Sensation- Thresholds25 50 75
100
Low
Absolute
threshold
Medium
Intensity of stimulus
Percentage
of correct
detections
Subliminal
stimuli
Subliminal
When stimuli are below one’s absolute threshold for conscious awareness
Lay audiences accept the idea of subliminal persuasion but it has not been substantiated in research

12. Sensation - Thresholds
Difference Threshold (aka JND – just noticeable difference)
minimum difference between two stimuli required for detection 50% of the time
Increases with the magnitude of the stimulus
Weber’s Law- to be perceived as different, two stimuli must differ by a constant minimum percentage
Stimuli must differ by a constant proportion not amount to be noticed
light intensity- 8% difference
weight- 2% difference
tone frequency- 0.3% difference
Try the following experiment: two envelopes, one with two quarters in it, the subject will be able to tell the difference, but then put the envelopes in a pair of shoes and try to tell the difference
Weber's Principle: difference thresholds grow with the magnitude of the stimulus
If you make $5 p/h a 25 cent hour raise will be noticeable but at $10 p/h you may need 50 cents.
If you are in sales, three piece suit and sweater, sell the suit first because after the suit the man will be more likely to buy
In car sales, after the sale customer won’t really notice $500 stereo
ADAPTation—habituation
After drinking tea with lemon, a grapefruit will not taste as sour
…but after a roll, it will taste especially sour
After holding salty water in mouth, it will taste less salty, and drinking fresh water afterwards, it will taste sweet

13. Sensory Adaptation
Diminished sensitivity as a consequence of constant stimulation
Example – you walk into a house and it smells, but an hour later you no longer notice the smell.
You get used to it – you adapt
Diminishing sensitivity to unchanging stimulus

14. End Day 1

15. Day 2 – Backmasking and Subliminal Clips and Discussion
Play several clips on subliminal messages and backmasking
Response: Students are to write a 2 paragraph response analyzing what they saw today (combined with Internet Research) and explain if subliminal and backmasking work.

16. Subliminal Commercials

17. End Day 2

18. Vision Amazing – how does light become images? Transduction
conversion of one form of energy to another
Stimulus energy becomes neural messages
Stimulus input is light energy
Not color that strikes the eyes, but electromagnetic energy that our visual system perceives as color
We se only a mall part of the color spectrum
2 parts of light help our sensory experience:
1. Wavelength - the distance from the peak of one wave to the peak of the next
Determines hue (color we experience)
2. Intensity – Amount of energy in the light waves
Influences brightness

19. Vision- Physical Properties of Waves
Short wavelength=high frequency
(bluish colors, high-pitched sounds)
Long wavelength=low frequency
(reddish colors, low-pitched sounds)
Great amplitude
(bright colors, loud sounds)
Small amplitude
(dull colors, soft sounds)

20. The Eye Light enters the eye through the cornea
Light bends to provide focus
Light then passes through the pupil
Pupil is an adjustable opening in the center of the eye
Pupil is regulated by the iris
Iris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening
Adjusts light intake by dilating/constricting in response to intensity or even inner emotions
Behind the pupil is the lens

21. The Eye Continued
Lens focuses the incoming rays into an image on the eye’s light sensitive back surface
Does this through the process of accommodation – changing the curvature
Retina contains the receptor rods and cones and layers of neurons that process the visual information
Rods – detect black, white and grey/peripheral and twilight vision
Cones – function in daylight and well-lit conditions/fine detail/color sensations
Fovea is the retina’s central area of focus add where cones cluster around
Fovea has cones but no rods

22. Vision

23. The blind spot occurs is the location in the retina where the visual cortex exits to the brain, there are no receptors there
What our brain does, typically, is fill in that missing piece based on what it estimates to be there
Blindsight—we can see things we don’t perceive

24. Vision Acuity – sharpness of vision Nearsightedness Farsightedness
Can be changed by slight variations in the shape of the eye
Nearsightedness
Light rays from distant objects focus in the front of the retina
Condition in which nearby objects are seen more clearly than distant objects
Farsightedness
The image of near objects is focused behind retina
Condition in which faraway objects are seen more clearly than near objects

25. Vision
Normal Nearsighted Farsighted Vision Vision Vision

26. Retina’s Reaction to Light
Optic nerve- nerve that carries neural impulses from the eye to the brain
Blind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there
Fovea- central point in the retina, around which the eye’s cones cluster

27. Retinal ganglion cells---go back to 5.3 and then to 5.4
5.4a is the cover of a catalog and students complained of seeing gray spots
The grid pattern is called the Hermann grid after the German physiologist who first discovered it
The elusive gray spots can be explained in terms of the receptive fields of the retinal ganglion cells
Some of the cells are an on center surrounded by an off (like a donut). Light has opposite, antagonistic effects

28. Vision- Receptors Receptors in the Human Eye Cones Rods Number
Location in
retina
Sensitivity in
dim light
Color sensitive?
Yes
Low
Center
6 million No
High
Periphery
120 million

29. Pathways from the Eyes to the Visual Cortex

30. Day 4 – Vision in more detail
KQLW Chart
Complete 1st 2 columns
What I already know/learned
Questions I have still
Watch videos (also on website for class)
G:\Eye\030 How Eyes Work - An Introduction.mp4
Start at 1:00 into the video
G:\Eye\032 Visual Processing in the Retina.mp4
Start at 4:00 minutes into video
Complete column 3
What I learned today
Complete column 4
What I still want to learn

31. Start Day 5

32. Visual Information Processing
Visual information goes from the retina in the eye to the thalamus then to the brain’s visual cortex in the occipital lobe
130 million rods and cones in the retina
Transmitted by the ganglion cells
Ganglions’ axons make up the optic nerve
Retinal cells are VERY sensitive
Can misfire
Even pressure can trigger misfires
Brain interprets the misfires as light

33. Feature Detection Ganglion cells send signals to the visual cortex
Feature detector neurons respond to a scene’s specific features
Edges, lines, angles and movements
Visual cortex passes information to other areas of the cortex that respond to more complex patterns

35. “Vast Visual Encyclopedia”
Cells that are distributed throughout the brain
Respond to one stimulus but not another
Called supercells
Fire only when cues trigger them too
Ex: A goalie blocking a shot when they see the ball or puck coming or anticipate the direction it might come from

36. How the Brain Perceives
Perception combines sensory input with assumptions and expectations
If you stare at the Necker cube, it changes every few seconds
This demonstrates that perception is shifting
Brain constructs varying perceptions

37. Parallel Processing Our brains process several things at once
Divides visual scene into dimensions
Color, depth, movement, and form
Our perceptions are based on integration of all from all the processing that happened simultaneously
Different areas of the brain process each part of the visual scene
Damage one area and certain parts of vision do not work
i.e. pouring a drink into a class – appears “frozen” – can’t see movement

38. Parallel Processing…

39. Summary of Processing of Visual Information

40. Color Vision Light rays are NOT colored
Color is in our brains – not in the object we see
The brain manufactures color
Theory is that any color can be created by combining light waves of 3 colors
Red, green, and blue
Retina only has 3 color receptors

41. Color-Deficient Vision
People who suffer red-green blindness have trouble perceiving the number within the design
They have only 2 color receptors
5.7 is an initial test for color blindness, students with scores above 16 have an 81 percent chance of failing a standard screening for color vision
8 percent of males, .05 percent of females show color weaknesses
Color defects are genetically transmitted, recent research has conclusively mapped this transmission
Monochromats—have no or only one type of functioning cone type and respond to light like a black and white film—colors are records only as gradations of intensity, likely to find daylight uncomfortable if no functioning cones, those with one cone okay but still can’t discriminate colors—very small number of people have this
Dichromats—one malfunctioning cone system, depending on type, various colors will not be perceived, inability to perceive blue is the rarest, in 1950 England, found 17 people

42. Opponent-Process Theory
After leaving receptor cells, visual info is analyzed in terms of if the opponent colors
Neurons are turned on and off by certain colors
“ON” “OFF”
red green
green red
blue yellow
yellow blue
black white
white black
5.9—shows that colors can be subjective, no wavelengths of light
Look in the center of this and many people will see wavy patterns of pastel , because the eye is constantly moving and these movements displace the image of the diagonal lines over the retinal receptors and create a pattern of receptor activity that typically occurs from viewing colored stimuli

43. Opponent Process- Afterimage Effect
We get tired of our green response by staring at green
So – when we stare at the white (which contains all colors), we see only the red part of the red-green pairing

44. Color Constancy
Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
In English – we see common objects as the same color even though the wavelengths may actually change.

45. End Day 5

46. Audition Audition Frequency Pitch the sense of hearing
the number of complete wavelengths that pass a point in a given time
Pitch
a tone’s highness or lowness
depends on frequency

47. The Intensity of Some Common Sounds
A recent U of Tenn. study found that 60 percent of college students suffer some high-frequency hearing loss
Loud music is believed to be the culprit
Live concerts—120 + decibels, louder than jack hammer, chainsaw
OSHA says that 85 decibels (food processor) 8 hours, 5 days a week will eventually cause permanent hearing loss
For each 5 decibel increase, the time it takes to cause lasting injury drops by half
Try: hold finger up as if taking a court room oath, rub thumb, finger together and should hear a scrtiching sound---if not, MAY have hearing loss

49. Audition- The Ear Middle Ear Inner Ear Cochlea
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, contining the cochlea, semicurcular canals, and vestibular sacs
Cochlea
coiled, bony, fluid-filled tube in the inner ear through which

50. Audition Place Theory Frequency Theory
the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated
Frequency Theory
the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

51. How We Locate Sounds
Experiment—have someone sit in front of class with eyes closed. Clap hands around head and ask student to identify where the sound comes from—will be able to do so when the sounds come from one side or the other, but less clearly able to do so when the sounds overhead in back or in front
The perceived difference in sounds is related to the time at which the sound is received

52. Audition Conduction Hearing Loss Nerve Hearing Loss
hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea
Nerve Hearing Loss
hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve
Ringing in the ears is called tinnitus, affects more than 36 million Americans
Most common cause is exposure to loud noises, but also can be caused by certain drugs, ear infections, food allergies
In most severe form, this ailment is incapacitating

53. Audition
Older people tend to hear low frequencies well but suffer hearing loss for high frequencies 1
time 10
times
100
1000 32 64
128
256
512
1024
2048
4096
8192
16384
Frequency of tone in waves per second
Low
Pitch
High
Amplitude required for
perception relative to
20-29 year-old group

54. Touch Skin Sensations pressure warmth cold pain
only skin sensation with identifiable receptors
warmth
cold
pain
Touch localization demonstration, concentrate on where the sensations of touch are felt:
Touch two index fingers together, feel it in both
Touch finger to bottom lip, light taps, felt mostly in lip even though both are being stimulated
Touch ankle, now its felt mostly in finger
Touch localization depends on the relative lengths of the pathways from the stimulated parts to the brain

55. Pain Gate-Control Theory
theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain
“gate” opened by the activity of pain signals traveling up small nerve fibers
“gate” closed by activity in larger fibers or by information coming from the brain
Pain is an important signal to our bodies
The experience of pain can be influenced by information from the brain
Chronic pain—est. that over 100 million people suffer from this
One study had teen age burn patients undergo a few minutes of wound treatment while they played Nintendo or while they were in a virtual reality environment—the patients felt less pain and spent less time thinking about their pain in virtual reality than Nintendo due to concept of “presences”—illusion of going inside another world. Pain requires attention

56. Taste Taste Sensations Sensory Interaction sweet sour salty bitter
the principle that one sense may influence another
as when the smell of food influences its taste
Some taste sensations are genetically programmed, such as sweet, and finding bitter and sour foods unpleasant
A study of babies had sweet eliciting smiles, lip smacking, and sour eliciting protrusion of tongue
These reactions make good evolutionary sense
Animals tend to be neophobic, and human children are reluctant to try new things
One experiment asked a group of subjects to taste two groups of food (that were the same). When the items were accurately named (chopped tomatoes, oatmeal, beefsteak) more willing them when given novel names (pendula fruit, lat, langua steak)
However, as true with other stimuli , mere exposure makes us like them more

57. Smell nerve Olfactory bulb Receptor cells in Nasal olfactory membrane
passage
Olfactory
bulb
nerve

58. Age, Sex and Sense of Smell
Women
Men
Age Group 4 3 2
Number
of correct
answers
Women and young adults
have best sense of smell
Smell can be used to identify gender
The phenomenon of women in the same home having the same menstrual cycle is related to smell—researcher Martha McClintock discovered this 30 years ago while at Wellesley College; now a researcher at the U of Chicago found that smell can stimulate ovulation
Citrus odors make people more alert, spiced apple helps relaxation
Pumping certain pleasant food odors cut by 40 percent shoving, pushing in New York subways
People in New York mall were more likely to help strangers when there was the aroma of roasting coffee or baking cookies
Good and Plenty licorice combined with cucumber increased female blood flow by 14 percent (anything over 10 percent was considered stimulating), baby talc 13 percent, lavender + pumpkin pie 11 percent
Cherry cut flow by 18 percent, charcoal barbecue 15 percent, men’s cologne by 1 percent
Women seem to be excited by things that remind them of childhood, or are fresh smelling, relating to safety and security needed in order to feel sexual

59. Body Position and Movement
Kinesthesis
the system for sensing the position and movement of individual body parts
Vestibular Sense
the sense of body movement and position
including the sense of balance
Ian Waterman, after viral infection, lost his sense of light touch and body position and movement—can walk but must look at limbs to direct them
When lights go out, he falls and cannot get up again until they come back on
When he is not looking at his body, he moves very little, unlike most of us who move around quite a bit
Synesthesia—sensory condition in which stimulating one modality leads to perception in another (to perceive together)
1 in 2,000 occurrence, females outnumber 6 to 1, seems to run in families so there may be a genetic base