MYERS FOR AP, UNIT 4
Sensation & Perception
DO NOW
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Which of your senses do you think
would be the hardest to live without?
Why?
AP OBJECTIVES
Discuss basic principles of sensory
transduction, including absolute
threshold, difference threshold, signal
detection, and sensory adaptation.
 Discuss the role of attention in
behavior
 Explain the role of top-down processing
in producing vulnerability to illusion.
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KEY TERMS & MORE KEY TERMS
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Sensation, p. 116
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Perception, p. 116
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Bottom-up
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processing, p. 116
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Top-down processing, p. 116 
Selective attention, p. 117 
Inattentional
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blindness, p. 118
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Change blindness, p. 119 
Psychophysics, p. 120
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Absolute threshold, p. 120 
Signal detection
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theory, p. 121
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Subliminal, p. 121
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Priming, p. 121
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Difference threshold, p. 122 
Weber’s law, p. 123
Sensory adaptation, p. 123
Transduction, p. 124
Wavelength, p. 125
Hue, p. 125
Intensity, p. 125
Pupil, p. 126
Iris, p. 126
Lens, p. 126
Retina, p. 126
Accommodation, p. 126
Rods, p. 126
Cones, p. 126
Optic nerve, p. 126
Blind spot, p. 127
Fovea, p. 127
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Feature detectors, p. 129
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Parallel processing, p. 130 
Young-Helmholtz trichromatic 
(three-color) theory, p. 132 
Opponent-process
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theory, p. 133
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Audition, p. 134
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Frequency, p. 134
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Pitch, p. 134
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Middle ear, p. 135
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Cochlea, p. 135
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Inner ear, p. 135
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Place theory, p. 137
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Frequency theory, p. 137
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Conduction hearing
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loss, p. 138
Sensorineural hearing
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loss, p. 138
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Cochlear implant, p. 138
Kinesthesis, p. 142
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Vestibular sense, p. 142
Gate-control theory, p. 143
Sensory interaction, p. 147
Gestalt, p. 151
Figure-ground, p. 151
Grouping, p. 152
Depth perception, p. 153
Visual cliff, p. 153
Binocular cues, p. 153
Retinal disparity, p. 153
Monocular cues, p. 154
Phi phenomenon, p. 156
Perceptual constancy, p. 156
Color constancy, p. 158
Perceptual
adaptation, p. 160
Perceptual set, p. 161
Extrasensory perception
(ESP), p. 166
Parapsychology, p. 166
KEY PEOPLE
Richard Axel
 Georg von Bekesy
 Linda Buck
 Gustav Fechner
 Eleanor Gibson
 Ewald Hering
 David Hubel
 Harry McGurk
 Ronald Melzack

James Randi
(again)
 Herman von
Helmholtz
 Richard Walk
 Patrick Wall
 Ernst Weber
 Torsten Wiesel
 Thomas Young
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TOP-DOWN PROCESSING
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Bottom-up processing
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Begins with sensory receptors and heads for the
brain.
We process this way when we don’t know
something; we start at the bottom and work our
way up.
Top-down processing
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Information that a person brings to the situation
that influences both perception and recognition
We process this way when we already know
things. We start at the top and integrate
information
An example: Stereotyping uses previous
expectations to make judgments
DISCUSSION
But wait! Stereotyping is bad, right? Why
is top-down processing so important?
 What are some of the pros and cons of
selective attention?
 How is selective attention related to the
evolutionary perspective?
 Give examples of when you were so
caught up in doing something that you
missed something you should have
attended to, or when the environment was
so distracting that you couldn’t focus.
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SAY WHAT???
Aoccdrnig to rscheearch at Cmabrigde
Uinervtisy, it deosn’t mttaer in waht
oredr the ltteers in a wrod are, the olny
iprmoetnt tihng is taht the frist and lsat
ltteer be at the rghit pclae. The rset can
be a total mses and you can sitll raed it
wouthit a porbelm. Tihs is bcuseae the
huamn mnid deos not raed ervey lteter
by istlef, but the wrod as a wlohe.
DO NOW: HOW SENSITIVE ARE YOU?
Complete the handout!
Highly sensitive persons:
 Are more aware of all the possibilities in a situation.
 Naturally process information from the environment more
carefully and study it thoroughly before acting.
 Are more aware of subtleties in their surroundings
 Are often intellectually gifted, unusually creative and productive
workers, and attentive and thoughtful in close relationships.
 Are more easily overwhelmed when in a highly stimulating
environment.
 Become exhausted when bombarded by multiple stimuli and
need more down time to recover.
Source: Aron, E. N. (1999). The highly sensitive person: How to thrive when the world
overwhelms you. New York: Random House.
SELECTIVE ATTENTION EXPERIMENT!
Human Earphones
 We need four volunteers!
 And two textbooks
 Dichotic listening
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INATTENTIONAL AND CHANGE
BLINDNESS
Umbrella video – inattentional
blindness
 How could this get us in trouble in real
life?
 Change Blindness videos:
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FIELD-DEPENDENT OR INDEPENDENT?
How fast can you find the
12 items?
Herman Witkin devised the
Embedded Figures Test
(EFT) to measure field
dependence–independence and
has studied this for more than 30
years)
•Field Dependent: Difficulty
locating hidden figures within
complex surroundings (prefer
social sciences and education)
•Field Independent: Easily locating
hidden figures (tend to favor
natural sciences, math and
engineering)
•Scores on field dependence–
independence are
relatively stable over time.
IMPORTANT DETAILS (NIB)
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Gustav Fechner developed three methods of
experimental measurement used to study
sensory phenomena:
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Method of limits (minimal stimulus gradually
increasing = JND)
Method of right and wrong: Present either single
stimuli at the threshold or pairs of stimuli that are
very similar, and the participant responds “yes”
or “no” if they perceive a difference or not.
Method of adjustment: Adjust a comparison
stimulus until identical to the standard stimulus
SIGNAL DETECTION
So WHAT? Who cares?
 Why does this matter, especially since
absolute thresholds and difference
thresholds vary?
 Answer: It’s critical to fields where
attention to detail amid environmental
distractions is paramount (air traffic
controllers, security screeners, law
enforcement, and even for YOU, when you
drive, for example.)
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WEBER’S LAW DEMO
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We need:
Three quarters
Two envelopes
A shoe
A volunteer (maybe one with a shoe?)
Application to marketing psychology: You’re a
salesperson. Imagine a customer who wants to
buy a three-piece suit and a sweater. To get
Which would you try to sell first and why?
THRESHOLD + SUBLIMINALS
http://www.garyfisk.com/anim/thresho
ld.swf
 DQ: What does the research say about
how subliminal messages influence (or
don’t)?
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SENSORY ADAPTATION
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Why don’t objects disappear from view
after prolonged exposure?
Demo #1—The vanishing
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Stare at a stationary object
Close one eye
Gently push in on the outside corner of the open eye
You should notice the object disappear briefly
Demo #2—Point of fixation:
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Choose a partner
Partner #1 stares at a stationary object.
Partner #2 stares at Partner #1’s eyes from the side.
Switch partners
What did you observe?
VISION
VISION:
STIMULUS INPUT= LIGHT ENERGY
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Transduction
(transform
electromagnetic
energy to neural
messages)
We only “see” a
small band of the
electromagnetic
spectrum.
THE PHYSICAL PROPERTIES OF WAVES
These properties apply to audition (hearing), too:
• The higher the frequency, the higher the pitch and vice versa
• The greater the amplitude the louder the sound and vice versa
THE EYE
Do Now: Sketch the eye into your notes describe, and
how it works
DQ: What do you suppose causes “red eye,” when
flash pictures are taken?
THE DETAILS OF NEURAL MESSAGING
RODS & CONES
Light demo
 Rods & Cones demo
 One to try at home: In a dark room (or
outside) focus on an image or object.
Notice how detailed the object appears.
Then focus your foveal vision just to the
side of the image or object you were
looking at. You should notice that the
image becomes more detailed
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STUFF YOU SHOULD KNOW
How the eye works with the thalamus
and the occipital lobes (review)
 Feature detector cells
 The significant difference in number
and function of rods and cones
 How parallel processing works with
vision (color, motion, form and depth)
 What if you could not perceive motion?
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HERMANN GRID (WHY?)
BLINDSIGHT
http://www.youtube.com/watch?v=Gw
Qe_FH1i1w
 http://www.youtube.com/watch?v=nFJ
vXNGJsws
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COLOR THEORY
Young-Helmholtz Trichromatic theory
 Herring’s opponent-process theory
 Afterimages
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STARE AT THE DOT IN THE IMAGE BELOW
WHAT DO YOU SEE (BLINK A BIT)
Stare at the tricolored dots on the photo for 30 seconds; then
shift your gaze to the X on the other side of the screen. Blink
several times. What do you see?
A QUESTION FOR THE AGES:
How do I know if I am seeing the same
color as someone else?
 Answer: The wavelength determines
color, so in a properly functioning eye, it
will be the same, although color shades
can vary significantly and people may
name them differently.
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COLOR BLINDNESS
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http://www.colourblindness.com/colour-blindnesstests/ishihara-colour-test-plates/
HEARING (AUDITION)
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Do now: Describe how our ears convert soundwaves
to neural impulses. Draw if it helps!
NOTE: ALTERNATIVE NAMES
The hammer is also called malleus
The anvil is also called incus
Stirrups are also called stapes
ANOTHER KEY QUESTION:
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DQ: Why does our voice sound unfamiliar when
we hear it recorded?
Answer: We hear the sound conducted by
sound waves and the sound carried directly to
the auditory nerve by bone conduction
How ears work:
http://www.youtube.com/watch?v=bKy02f1pD4
http://www.youtube.com/watch?v=VxcbppCX6
Rk
Sound location demo
KEY QUESTIONS:
What causes hearing loss and what are
the two main types?
 How loud is too loud? (What is the general
rule?)
 How (mechanically) do we perceive
loudness?
 How do we understand pitch perception?
Know the difference between place and
frequency theory
 How do we locate sounds?
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WHAT ABOUT TOUCH?
What are the four basic skin sensations?
 What is the difference between
kinesthesis and vestibular sense?
 Demo:
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Stand on one foot with your eyes open
 Stand on one foot with your eyes closed
 Really brave volunteer? (plus spotters) Spin
around in a circle six times, and then try to
stand on one foot with your eyes closed.
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PAIN IS WEIRD AND WE DON’T
UNDERSTAND IT COMPLETELY
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Do Now: Why would it be bad not to feel pain? Do you
think people who don’t feel pain have normal life
expectancy? Why or why not?
Nociceptors – respond to hurtful pressure, temperature
and chemicals
There are different kinds of “pain personalities:”
dysfunctional, interpersonally distressed and adaptive
copers
Placebos can relieve pain. So can hypnosis, biofeedback,
physiotherapy, ultrasound, acupuncture, relaxation,
electrical stimulation and massage.
P.S. Be familiar with the Gate-Control Theory (Mezack and
Wall). It is SO biopsychosocial
TASTE!
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Well, for starters…
This taste map is bogus!
See for yourself
Plus they forgot umami
Mmmm… kisses
Check out your book for more details and fun
facts.
Here’s one that’s not in the book: Whether we
like something or not depends on what we
THINK. (Pilner & Pelchat study)
HOW WE SMELL
SMELL!
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Do now: 8 little vials are going around with scents inside.
Smell quietly and try to identify all of them (in your
notebook, not out loud)
We have 10 to 20 million olfactory receptors that can
identify 10,000 odors
Our senses of taste and smell decline over time
Top-down processing (associations, etc.) help us decide if
things smell good or bad
Gender demo: We need two main volunteers, a blindfold
and everyone else to participate. (Modified Wallace
Experiment)
http://blogs.scientificamerican.com/but-notsimpler/2013/11/12/green-eggs-and-ham-dont-let-itwaste-what-doctor-seuss-knew-about-the-science-oftaste/
GESTALT
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The unified whole is different from the
sum of the parts.
GESTALT INCLUDES THESE ELEMENTS:
GESTALT: FIGURE & GROUND
DEPTH PERCEPTION
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Monocular Cues activity with ball pit balls
Photo walk (choose a partner & make sure you
have a camera). Take a 15-minute walk and look
for monocular cues (see page 155 for reminders)
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Relative height
Linear perspective
Relative size
Interposition
Relative motion
Light and shadow
Monocular cues rely on previous knowledge to
make sense. Top-down processing, again!
CAREFULLY REVIEW!
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Phi Phenomenon
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Perceptual constancy:
 Shape
and size constancy
 Lightness constancy
 Color constancy
TROXLER FADING AND THE PHI PHENOMENON
STARE AT THE + IN THE MIDDLE AND NOTICE WHAT
HAPPENS
The context
helps us to
perceive the
stimulus in
the simplest
manner
Again, the
context
helps us to
perceive the
stimulus in
the simplest
manner
Notice that
you can only
perceive the
center
stimulus
one way at
any given
moment
SMELL