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Myers’ PSYCHOLOGY for AP
Unit 4
Sensation &
Perception
Sight, Smell, Taste, Touch,
Hearing. If you had to do
without one, which would it
be?
Sensation
Sensation: detecting stimuli from the body or surroundings.
Perception: interpreting and organizing sensations into
meaningful patterns.
Sensation
 Sensation
 a process by which our sensory
receptors and nervous system receive
and represent stimulus energy
 Perception
 a process of organizing and interpreting
sensory information, enabling us to
recognize meaningful objects and
events
Sensation
 Our
sensory
and
perceptual
processes
work
together to
help us
sort out
complex
processes
What if we could sense everything?
Life would hurt.
So we can only take in a window of what is out there.
Psychophysics: studies the relationship between physical
stimuli and our psychological experiences to them.
Sensation
 Bottom-Up Processing
 analysis that begins with the sense receptors
and works up to the brain’s integration of
sensory information
 Top-Down Processing
 information processing guided by higher-level
mental processes
 as when we construct perceptions drawing on
our experience and expectations
Top-Down Processing
 For example, stereotyping since both previous expectations to make
judgements about the world around us.
 Stereotyping can be negative, it can also be efficient for people as
they interact with certain stimuli.
 Without top down processing, we would interpret the world as if it
were constantly new.
 Like learning how to add everyday in math or 50 First Dates!
https://www.youtube.com/watch?v=ErjP5xMTc8I
Remember, TDP - we process this way when we have prior
knowledge. We start at the top and have to work to process details.
Stroop Effect
On the next slide, you are to follow the
instructions below:
Look at the image and say aloud
the color of each word. Do not read the
words! Just say what color they are.
Stroop Effect: How does it
work?
 The words themselves interfere with your ability to
quickly say the correct color of the word. Two different
theories have been proposed to explain this
phenomenon:
 Selective Attention Theory: According to this theory,
naming the actual color of the words requires much
more attention that simply reading the text.
 Speed of Processing Theory: According to this
theory, people can read words much faster than they
can name colors. The speed at which we read makes it
much more difficult to then name the color of the word.
Be the Experimenter…
Consider the following:
 Try the experiment with a young child that has
not yet learned to read. How does the child's reaction
time compare to that of an older child who has learned
to read?
 Try the experiment with uncommon color names,
such as lavender or chartreuse. How do the results
differ from those who were shown the standard color
names?
Bottom Up Processing
BUP is when we have no prior knowledge.
We start at the bottom and work our way
up.
Also called “small chunk” or “data”
processing.
http://www.youtube.com/watch?v=yKBYL7
QnFkE – watch on your own!
Perception

Selective Attention
awareness on a particular stimulus

Those with ADHD have an inability to
be selectively attentive. Instead of
attending to the important stimuli and
filtering out unimportant ones, they attend
to all stimuli in the environment making
it difficult to process information
correctly.
focus of conscious
Try this…
Instructions…
1. Do NOT talk OR YOU will ruin it for
others.
2. Pay attention to what I am going to play
for you.
3. Listen and do what the Video tells you
to. http://www.youtube.com/watch?v=IGQmdoK_ZfY
Change Blindness
 Is a psychological phenomenon that occurs when a change in a
visual stimulus goes unnoticed by the observer.
 For example, an individual fails to notice a difference between two
images that are identical except for one change.
 The reasons these changes usually remain unnoticed by the
observer include obstructions in the visual field, eye movements, a
change of location, or a lack of attention.
 The brain regions that have been observed as active during change
blindness are the prefrontal lobe, the cerebellum, the inferior
temporal gyrus, the parietal lobe, and the frontal lobe.
http://www.youtube.com/watch?v=VkrrVozZR2c
Selective Attention & Flow
 These concepts are related…
When people get caught up in an experience
that they miss out an obvious stimuli in the
environment, they are said to be having a flow
experience.
Flow is coined by Mihaly Csikszentmihalyi and
involves being skilled at a challenging task that
takes away our sense of self consciousness and
awareness of time and the presence of others
around us.
Selective Attention & the
Evolutionary Perspective
If we had to attend to every stimulus in
the environment (noise), we might be
hindered from action.
However, if we miss important stimuli in
the environment due to attention that is
too selective, we may fall victim to all
sorts of trouble…falls, car accidents etc.
Is there a gender difference in
selective attention?
Sensation- Basic
Principles
 Psychophysics
 study of the relationship between
physical characteristics of stimuli and
our psychological experience of them
 Light- brightness
 Sound- volume
 Pressure- weight
 Taste- sweetness
Gustav Fechner
Established 3 methods of experimental measurement used to study sensory
phenomena.
 Method of Limits – begin with minimal stimulus and increase it until the
subject can perceive it. – Determines JND
 Method of Right and Wrong Cases – present identical stimuli repeatedly
– either single stimuli at the threshold or pairs of stimuli that are very
similar. The subject responds “yes” if perceived or if a difference exists
or “no” if not perceived or different.
 Method of Adjustment – adjust a comparison stimulus until it appears
identical to the standard stimulus. Every error is recorded and after
many trials, the average error is computed. It too, provides a measure
of JND.
Sensation- Thresholds
 Absolute Threshold
 minimum stimulation needed to detect a
particular stimulus 50% of the time
 Difference Threshold
 minimum difference between two stimuli
required for detection 50% of the time
 just noticeable difference (JND)
Why Do We Care About Signal
Detection?
Extremely important in fields where
attention to detail amid environmental
distractions is paramount – air traffic
controllers, policemen, drivers etc.
Sensation- Thresholds
 Signal Detection Theory
 predicts how and when we detect the presence
of a faint stimulus (signal) amid background
stimulation (noise)
 assumes that there is no single absolute
threshold
 detection depends partly on person’s
 experience
 expectations
 motivation
 level of fatigue
Sensation- Thresholds
100
Percentage
of correct
detections
75
50
Subliminal
stimuli
25
0
Low
Absolute
threshold
Intensity of stimulus
Medium
 Subliminal
 When stimuli are below
one’s absolute threshold
for conscious awareness
 http://www.youtube.co
m/watch?v=1NpBMAKdg
nQ
 While sub messaging may not
work, priming does. If we are
exposed to stimuli about a
specific subject we are more
likely to recognize information
about that subject in the
environment.
Anthony Pratkanis & Factors Contributing to
Public’s Beliefs of Subliminal Influence
Popular accounts of subliminal influence appeal
to the pop psychology of the day.
Popular accounts link subliminal influence to the
issue of the day.
Many of the popular articles fail to report
scientific evidence that is critical of claims for
subliminal persuasion.
Belief in subliminal persuasion may serve as a
need for many individuals.
Sensation- Thresholds
 Weber’s Law- to perceive as different, two stimuli
must differ by a constant minimum percentage
 light intensity- 8%
 weight- 2%
 tone frequency- 0.3%
 Everyone…take off 1 shoe, take out 3
quarters…
 Sensory ADAPTation- diminished sensitivity as a
consequence of constant stimulation
Sensory Adaptation
Tendency of sensory receptors
to respond less and less to
constant stimulation.
Do you feel your underwear all day?
Sensory Adaptation
• 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
Vision
Our most dominating
sense (Visual Capture).
The eye is like a camera
(it needs light).
Vision- Stabilized
Images on the Retina
Vision
 Transduction
 conversion of one form of energy to
another
 in sensation, transforming of stimulus
energies into neural impulses
 Wavelength
 the distance from the peak of one
wave to the peak of the next
Vision
 Hue
 dimension of color determined by
wavelength of light
 Intensity
 amount of energy in a wave
determined by amplitude
 brightness
 loudness
The spectrum of
electromagnetic
energy
Vision- Physical
Properties of Waves
Short wavelength=high frequency
(bluish colors, high-pitched sounds)
Great amplitude
(bright colors, loud sounds)
Long wavelength=low frequency
(reddish colors, low-pitched sounds)
Small amplitude
(dull colors, soft sounds)
Think Rainbow!
Wavelength & Amplitude
Helpful Hints
Vision & Audition use similar terms to
discuss the different stimuli that are
processed by our visual and auditory
systems. They both work in waves.
Wavelength – determines the quality of the
waves (for vision, colour, for sound pitch)
 Amplitude – determines the intensity of the
waves (for vision, brightness, for sound,
loudness)
Vision
 Pupil- adjustable opening in the
center of the eye
 Iris- a ring of muscle that forms the
colored portion of the eye around the
pupil and controls the size of the
pupil opening
 Lens- transparent structure behind
pupil that changes shape to focus
images on the retina
Vision
Vision
 Accommodation- the process by which the eye’s lens
changes shape to help focus near or far objects on the
retina
 LINK! In sensation, accommodation refers to the ways
the muscles in the way the eye change the shape of
the lens BUT it can also refer to the ways in which we
change our schemas to incorporate new information we
learn.
 Retina- the light-sensitive inner surface of the eye,
containing receptor rods and cones plus layers of
neurons that begin the processing of visual information
Vision
 Acuity- the sharpness of vision (fovea!)
 Nearsightedness- condition in which
nearby objects are seen more clearly than
distant objects because distant objects in
front of retina
 Farsightedness- condition in which
faraway objects are seen more clearly
than near objects because the image of
near objects is focused behind retina
Vision
 Normal
Vision
Nearsighted
Vision
Farsighted
Vision
Retina’s Reaction
to Light- Receptors
 Rods
 peripheral retina
 detect black, white and gray
 twilight or low light
 Cones
 near center of retina
 fine detail and color vision
 daylight or well-lit conditions
More About the Retina!
The cells that make up the retina seem
backward.
Rods and Cones located at back of retina.
Then, bipolar and ganglion cells are on
top forming layers.
Light is interpreted by the rods and cones
first, even though it actually passes
through the other layer first!
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
Vision- Receptors
Receptors in the Human Eye
Cones
Rods
Number
6 million
120 million
Location in
retina
Center
Periphery
Sensitivity in
dim light
Low
High
Color sensitive?
Yes
No
Pathways from the Eyes
to the Visual Cortex
Visual Information
Processing
 Feature Detectors
 nerve cells in the brain that
respond to specific features
 shape
 angle
 Movement
 Visual Capture
 tendency for vision
to dominate the
other senses
Cell’s
responses
Stimulus
Blindsight
Is the ability to respond to visual information
without consciously seeing it.
Anthony Marcel argues that those people have
superb vision but they don’t know they can see.
His research suggests that their vision remains
in tact only the neural areas that bring vision
into awareness are impaired.
Acquired through damage.
http://www.youtube.com/watch?v=R4SYxTecL8E
How the Brain
Perceives
Illusory Contours
Visual Information
Processing
 Parallel Processing
 simultaneous processing of several aspects of a problem
simultaneously
 Our brains are so capable of processing multiple types of
stimuli from the environment that no computer can truly
replicate the human brain.
Visual Information
Processing
 Trichromatic (three color) Theory
 Young and Helmholtz
 three different retinal color receptors
 red
 green
 blue
Color-Deficient Vision
 People who suffer redgreen blindness have
trouble perceiving the
number within the design
 People who are colourblind see the colour as
muted grey or brown but
they have been trained to
identify the deficient
colour as red, blue or
grey. Don’t even know
they are colourblind!
Visual Information
Processing
Opponent-Process Theory- opposing retinal
processes enable color vision
“ON”
“OFF”
red
green
green
red
blue
yellow
yellow
blue
black
white
white
black
Opponent ProcessAfterimage Effect
After Images…LINK
 In vision, the opponent process theory states that the
perception of colour operates in an opposing tendency,
that is, when one colour works, when its pair colour
does not.
 Similarly, sympathetic and parasympathetic systems
work together as opposing processes.
 Neuron Firing “All or None” Depolarization and
Polarization
When one system is operating the other is not!
Visual Information
Processing
 Color Constancy
 Perceiving familiar objects as having
consistent color, even if changing
illumination alters the wavelengths
reflected by the object
Why do we have two ears?
Localization of Sounds
Sounds that reach one ear sooner than the
other ear cause us to localize the sound. It’s
also louder for one ear.
Hearing Deficits
Older people tend to hear low frequencies well but suffer
hearing loss when listening for high frequencies.
http://www.noiseaddicts.com/2009/03/can-you-hear-this-hearing-test/
Deafness
Conduction Deafness
 Something goes wrong
with the sound and the
vibration on the way to
the cochlea.
 You can replace the
bones or get a hearing
aid to help.
Nerve (sensorineural) Deafness
 The hair cells in the cochlea
get damaged.
 Loud noises (concerts) can
cause this type of deafness.
 NO WAY to replace the hairs.
 Cochlear implant is possible.
Audition
 Audition
 the sense of hearing
 Frequency
 the number of complete wavelengths
that pass a point in a given time
 Pitch
 a tone’s highness or lowness
 depends on frequency
The Intensity of Some
Common Sounds
Audition- The Ear
 Middle Ear
 chamber between eardrum and cochlea containing three tiny
bones (hammer malleus, anvil incus, stirrup stapes) 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
 Cochlea
 coiled, bony, fluid-filled tube in the inner ear through which
Bone Conducted Hearing
 Bone conduction is the conduction of sound to the
inner ear through the bones of the skull.
 Bone conduction is the reason why a person's voice sounds
different to him/her when it is recorded and played back. Because
the skull conducts lower frequencies better than air, people
perceive their own voices to be lower and fuller than others do.[This
also explains why a recording of one's own voice sounds higher
than one is accustomed to.
 http://www.youtube.com/watch?v=1SFHNR7Lp4E
Audition
 Place 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
Helpful Points to Avoid Confusing
the Theories of Sound
In place theory, different theories of sound
waves are said to vibrate different places on the
cochlea. These places are wired to different
parts of the auditory cortex in the brain so the
sound can be processed correctly.
In frequency theory, the entire cochlea is
believed to vibrate a particular frequency, thus
sending the signal of quality of sound to the
brain.
How We Locate
Sounds
Audition
 Conduction 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
Cochlear Implant
http://www.youtube.com/watch?v=Poyj7
U2wzhQ
http://www.youtube.com/watch?v=HTzTt
1VnHRM
http://www.youtube.com/watch?v=WDDf
GMuofuw
Audition
 Older people tend to hear low
frequencies well but suffer hearing loss
for high frequencies
Amplitude required for
perception relative to
20-29 year-old group
1
time
10
times
100
times
1000
times
32
64
128
256
512
1024 2048 4096
8192 16384
Frequency of tone in waves per second
Low
Pitch
High
NEXT DAY
Touch
 Skin Sensations
 pressure
 only skin
sensation with
identifiable
receptors
 warmth
 cold
 pain
Types of Skin
2 Types of Skin:
1. Hairy Skin – contains hair cells, which
detect movement and pressure.
2. Glabrous Skin – contains no hair cells, so
the receptors in this type of skin are
more sensitive…found mainly on palms,
bottoms of feet and lips!
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
Gate Control Continued
Helps explain why people aren’t always aware of
pain.
Pain signals can be controlled by the brain.
Brain can sometimes choose which pain to
consider and which ones to ignore, blocking off
pain signals in the spinal cord that it chooses to
ignore.
 Athletes who choose to ignore and play through injuries
and might explain why acupuncture works.
Gate Control Theory
 Contends that there is an area in the spinal cord
that can act like a “gate” and either inhibit pain
messages or transmit them to the brain.
 When tissue is injured, the small nerve fibers
activate and open the neural gate, and you feel
pain.
 Large-fiber activity closes the pain gate, turning
pain off (through stimulation like massage or
acupuncture).
Phantom Limb
Sensations that occur when a person the
presence of a limb after it has been lost.
Symptoms can include severe pain
sensation in the lost /removed limb.
http://www.youtube.com/watch?v=hlQZm
NlPdHQ
Phantom Limb Pain
Phantom limb pain is a
frequent complication
of amputation.
Client complains of
pain at the site of the
removed body part,
most often shortly
after surgery.

Show Phantom Limb Video (Secrets of the
Mind)
NO PAIN, No Gain?!
Some people are born without the ability
to experience pain…why is some pain
good?
It allows us to determine injury, sickness and
danger.
Often people who cannot experience pain do
not live long past their teens…dying of painful
illnesses they cannot feel.
A Painful LINK to Remember!
 Pain can be remembered differently depending on our
moods – mood congruent memory…if we were in a good
mood when we experienced pain, our memories of it
may not be negative!
 Cultural differences affect how we perceive pain, or
what type of pain we may perceive as being negative. If
we know pain is coming, and of we expect it to be part
of the growth experience, we may not be bothered by it.
Dennis Turk’s Subtypes of
People at Pain Centers
 Dysfunctional patients report high levels of pain and
psychological distress and believe they have little control
over their lives and are extremely inactive.
 Interpersonally distressed patients feel they have little
social support and report others don’t take their pain
seriously.
 Adaptive copers report far less pain and social distress
than others and continue to function at a relatively high
level.
Taste
 Taste Sensations (evolutionary perspective…)
 sweet - energy source
 sour – potential toxic acid
 Salty - essential sodium
 Bitter – potential poison
 umami - savory
 Sensory Interaction
 the principle that one sense may influence another
as when the smell of food influences its taste
Synesthesia
Are you a synesthete? c
What might it be like?
http://www.youtube.com/watch?v=vEqmNX8uKlA
Synesthesia is a perceptual condition of mixed
sensations: a stimulus in one sensory modality (e.g.,
hearing) involuntarily elicits a sensation/experience in
another modality (e.g. vision). Likewise, perception of a
form (e.g., a letter) may induce an unusual perception
in the same modality (e.g. a color)
http://www.youtube.com/watch?v=aD-ASiSpBXc
Supertasters!
Linda Bartishuk describes taste buds (papillae)
as being innervated by two cranial nerves: one
carries taste and the other carries pain and
touch.
Super tasters feel more pain from lesions on the
tongue – ie. Chilli peppers, carbonation and
ethyl alcohol.
Fat in food is also perceived as a touch
sensation….you could be a super perceiver of
fat in food.
Taste and Smell
Smell
Olfactory
nerve
Olfactory
bulb
Nasal
passage
Receptor cells in
olfactory membrane
Taste
 We have bumps on our tongue called
papillae.
 Taste buds are located on the
papillae (And the roof of the
mouth).
 Sweet, salty, sour, bitter and
recently umami (savory).
 Bitterness detectors – critical
because most poisons are bitter.
 Sour detectors – detect bad foods.
 Built-in salt and sugar needs for
survival.
Smell (“Olfaction”)
 Cilia – receptor cells that
collect molecules of odor.
 Olfactory bulbs – receives an
electrical signal and generates
a “code” that is sent to the
brain for interpretation.
 We can detect over 10,000
odors and odors have the
power to evoke memories and
feelings!
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
Age, Sex and Sense
of Smell
Number
of correct
answers
Women and young adults
have best sense of smell
4
Women
3
Men
2
0
10-19
20-29
30-39
40-49
50-59
60-69
Age Group
70-79
80-89 90-99
Eye and Ear Assignment
Please use the terms to complete the
story! You can hand it in next class Get
started now!
Wednesday
Lab day 216
HW- Sensation video and questions due
next class after lab day!
Monday- Gender Presentations
Wednesday- Jelly Bean Lab
Friday- Perception/illussions lab plus take
home quiz