Download PSYC 2301 Chapter 3

DE BO R AH
M.
L IGH T
MIST Y
G.
H UL L
CO CO
BAL L ANT Y NE
Chapter 3: Sensation and perception
Courtesy Dr. Julie Gralow
Copyright © Macmillan education 2015
LEARNING OBJECTIVES: Part 1
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LO 1 Define sensation and perception and explain how they are different.
LO 2 Define transduction and explain how it relates to sensation.
LO 3 Describe and differentiate between absolute thresholds and difference
thresholds.
LO 4 Explain how electromagnetic energy is transduced into a sensation of vision.
LO 5 Describe the function of rods and cones.
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LEARNING OBJECTIVES: Part 2
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LO 6 Compare and contrast the theories of color vision.
LO 7 Summarize how sound waves are transduced into the sensation of hearing.
LO 8 Illustrate how we sense different pitches of sound.
LO 9 Describe the process of olfaction.
LO 10 Discuss the structures involved in taste and describe how they work.
LO 11 Describe how the biopsychosocial perspective is used to understand pain.
LO 12 Illustrate how we sense the position and movement of our bodies.
LO 13 Identify the principles of perceptual organization.
LO 14 Identify concepts involved in depth perception.
LO 15 Define extrasensory perception and explain why psychologists dismiss its
legitimacy.
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To help us understand sensation and perception, meet the Dunn
sisters.
Sophie (left), Zoe, and Emma (front), are the world’s only deaf and blind triplets. Emma
and Zoe can see nothing, while Sophie has very limited vision even when wearing
corrective lenses. All three girls wear devices known as cochlear implants, which simulate
the sensation of hearing.
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Sensation and Perception 101: Part 1
Sensation
Perception
 Process by which receptors in
our sensory organs (such as in
the eyes, ears, nose, mouth,
skin and other tissues) and the
nervous system receive and
detect stimuli
 Process through which
information about these stimuli
is organized, interpreted, and
transformed into something
meaningful
Copyright © Macmillan education 2015
Sensation and Perception 101: Part 1
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Sensation & Perception
Transduction
– The process of transforming stimuli into the electrical and chemical signals of
neurons. Transduction is the first step of sensation.
– The neural signals are then processed by the central nervous system, resulting in
what we consciously experience as sensations (seeing a person’s face or smelling
smoke).
– In order for sensations to be useful, we must assign meaning to them (that face
belongs to my girlfriend or the scent of smoke signals fire).
– This process of organizing and understanding incoming information is perception.
– Sensation is seeing a red burner on the stove; perception is thinking hot.
– Sensation is hearing a loud, shrill tone; perception is recognizing it as the warning
sound of a fire alarm.
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Are you a synesthete?
Painter David Hockney stands before his massive Bigger Trees Near Water at an exhibition in London.
Hockney reportedly has synesthesia, a rare condition whereby a person experiences a combination of
perceptions in response to a “single sensory modality.” (Rich & Mattingley, 2002)
A synesthete may, for instance, describe the color green as having a scent, or the world “Tuesday” as
being maroon with black stripes. Hockery created the stage sets for various operas by painting what he
saw in the music (Ward, 2006, June 10).
Copyright © Macmillan education 2015
Sensation and Perception 101: Part 2
Sensory input
from
environment
Translates in
electrical and
chemical signals
of neurons
Resulting in
SENSATION
Through
TRANSDUCTION
Sensations
assigned
meaning
Neural signals
processed by CNS
Through
PERCEPTION
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Sensation and Perception 101
Data-based and Knowledge-based Processing
Data-based processing
 Describes how the brain takes basic sensory information and processes
the incoming stimuli. It is the equivalent to what cameras and video
recorders do best – collects data without any preconceived notions or
expectations.
Knowledge-based processing
 Generally involves the next step, utilizing past experiences and
knowledge to understand sensory information. It is the arena where
humans excel. Our brains constructs a representation of the world
based in what we have learned and experienced in the past.
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Sensation and Perception 101: Part 3
STUDYING SENSATION
Human sensation
 Great variability in stimulus detection in humans (state of mind and body)
 Sensory systems prone to interference making study difficult.
 Not everyone is born with the same collection of stimulus-detecting equipment.
 Approximately 2% of people might be able to multitask flawlessly, the great majority of us are limited
to our ability to attend to our environments, especially when we are focusing on more than one task
that demands our attention.
Absolute thresholds
 Weakest stimuli detected 50 percent of the time (being able to see a flame of one candle 30 miles
away 50% of the time (Galanter, 1962).
 Not necessarily for particular person over time
THE TRIPLETS
 Zoe became increasingly frustrated with a musical toy. Her mother noticed this behavioral change
and consulted a specialist.
 A problem with Zoe’s sensory receptors in her ears was found.
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Absolute Thresholds
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Sensation and Perception 101: Part 4
STUDYING SENSATION
Sensory adaptation
Difference thresholds
 the between two stimuli noticed 50 percent of the time (See
also Just noticeable difference)
Most people are painfully aware of their new braces, but after a
while they begin to notice them less. If a stimulus is ongoing
and steady, we tend to become less aware of it. This process of
sensory adaptation helps keep us on alert for changes in the
environment.
Sensory adaptation: a natural lessening of awareness of
unchanging conditions. This allows us to focus instead on
changes in our environment – a skill that has proven invaluable
for our survival.
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Sensation and Perception 101: Part 5
STUDYING SENSATION
Ernst Heinrich Weber’s Law (1795-1878)
 Thresholds are determined by ratios, not absolute numbers.
 The five senses each have their own Weber ratios.
Subliminal influences
 Do subliminal stimuli, which are well below our absolute thresholds (such as light that is too dim to
see and sounds that are too faint to hear), have an impact on us? “Subliminal advertising,” or stealthy
attempts by marketers to woo you into buying their products without you even being aware.
Do you believe people can be manipulated by these influences? Why? Why not?
Urban myth – Subliminal marketing cannot manipulate you to purchase something you had not planned
on purchasing, or to quit smoking, for example (Karremans, Sttoebe, & Claus, 2006).
 Neuroimaging studies suggest neural activity is evident with subliminal presentation of stimuli. The
brain does respond to information presented at unconscious or nonconscious level. What subliminal
messages may be able to do is influencing fleeting moods through priming (stimulating memories
beneath awareness through previous exposure, chapter 6). Example, pictures of dead bodies or
buckets of snakes) for several milliseconds (thus “priming” them) neutral picture of a woman rated as
more unlikable.
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Sensation and Perception 101: Part 6
STUDYING SENSATION
Signal detection theory
 Explains how various factors influence ability to detect weak
environmental signals
 Suggests the ability to detect a stimulus depends on sensory factors
(such as the intensity of the stimulus or the presence of interfering
stimuli) and psychological state (such as how alert one is)
Copyright © Macmillan education 2015
Show What You Know: Part 1
1. ________ makes the information received by the sensory receptors more
meaningful by drawing from experience to organize and interpret sensory data.
a. Perception
b. Transduction
c. Sensation
d. Signal detection
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Show What You Know: Part 2
2. Imagine you have been asked to watch a neighbor’s property while she is away. According to
signal detection theory, what factors may influence your ability to detect an intruder’s flashlight
in the middle of the night?
Signal detection theory states that various sensory factors and a person’s psychological state
influence the ability to detect weak signals in the environment. Some things that may influence
one’s ability to detect an intruder’s flashlight include the intensity of the light, level of alertness,
the expectations about one’s role, and other interfering stimuli in the environment.
3. At the supermarket, a woman next to you in line has some very strong-smelling cheese in her
basket. You notice the odor immediately, but within a matter of minutes you can barely detect it.
This reduced sensitivity to a constant smell results from the process of:
a. sensation.
b. transduction.
c. perception.
d. sensory adaptation.
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Vision: Part 1
LIGHT IS SIGHT
 Eyes do not sense faces, objects, or
scenery—they detect light!
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Visible light is the only part of the
spectrum detectable by human eyes.
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Electromagnetic (EM) waves in
everyday life
 Gamma waves
 X-rays
 Ultraviolet
 Infrared
 Microwaves
 Radio waves
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Visible Light and the Electromagnetic Spectrum
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Vision: The Colors We See
Features of light: Color factors
 Hue
 Brightness
 Saturation
Perception of color
 Perceptions of color are product of what is in the environment and
brain’s interpretation.
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Try This
 Go find the brightest, most saturated object you possess that has a
yellow hue, and grab a strong flashlight while you are at it.
 Wait until it is dark outside.
 Now put the object on a table right in front of you and look at it with a
dim light shining overhead.
 Next, shine the flashlight directly onto the yellow object and notice
how your perception of the color changes.
 Finally, turn off all the lights in the room and notice again how your
perception of the color changes.
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Vision: Part 2
Cornea
 Includes clear outer layer over colored portion of eye
 Shields eye from damage by dust, bacteria, and pokes
 Focuses incoming light waves
Iris
 Includes muscle responsible for changing size of pupil
Pupil
 Controls amount of light entering eye
Lens
 Includes tough, transparent structure that focuses incoming light and changes
shape to adjust images to near and far through accommodation.
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Vision: The Retina
Retina
 Contains photoreceptor cells and site for
transduction
Photoreceptors
 Absorb light energy and convert it into neural
activity
 Rods
 Cones
Rods and Cones
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Vision: Part 3
The retina
 Bipolar cells
 Optic nerve
 Blind spot
 Fovea
 Optic chiasm
 Interneurons
 Feature detector
Can you describe each of these terms?
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Vision: Part 4
Dark adaptation
 Ability of eyes to adjust to
dark after exposure to
brightness
Light adaptation
 Ability of eyes to adjust to
light after being in dark
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SEEING…After all these definitions, let’s put it all together!
 Light waves bounce off an object and enter eye through the cornea,
pupil, and lens.
 Iris dilates and contracts pupil to control amount of light entering eye.
 Cornea and lens focus light waves toward the retina, bending the light
and projecting an inverted image.
 Light strikes the retina, exciting photoreceptors.
 Rods and cones fire, activating bipolar cells found in retina.
 This excites ganglion cells, which form the optic nerve carrying
messages to the brain.
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Vision: Part 5
Theories of color vision
The trichromatic theory
 Three types of cones: red, green, and blue
 Brain identifies precise hue by calculating
patterns of excitement among three cones.
 Relative activity of three types of cones that
brain uses to make its color calculations
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Vision: Part 6
Theories of color vision
Code deficiency and color blindness
 Color deficiency occurs with loss or damage to
cone(s).
 Deficiencies may stem from problems with
cones.
 Red-green color defects
 8 percent male and >1 percent female with
European ancestry
See It?
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Vision: Part 7
Theories of color vision
Opponent-process theory
 Herring proposed theory to explain afterimage effect and suggested a
special group of neurons responds to opponent colors (in addition to
color-sensitive cones).
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Across the World
COLORS AND CULTURE
 Perception of color may vary
significantly across cultures, and
even between individuals, but
the early stages of sensation are
virtually the same for everyone
with normal vision.
 China: Red is lucky color.
 Nigeria: Red is bad fortune.
 U.S.: White represents virginity
and cleanliness.
 East Asia: White associated with
dying and bereavement.
 Blue: Most popular favorite
color in world
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Show What You Know: Part 3
1. The hue of a color is determined by the wavelength of the light reflecting off an
object.
2. Cells contained in the retina that absorb light energy and turn it into chemical and
electrical signals are called _____.
a. opponent-processing
b. photoreceptors
c. fovea
d. feature detectors
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Show What You Know: Part 4
3. Explain the two theories of color vision presented in the chapter and how they differ.
The trichromatic theory of color vision suggests there are three types of cones, each sensitive to particular
wavelengths in the red, green, and blue spectrums. The brain identifies a precise hue by calculating patterns
of excitement among the three types of cones, that is, the relative activity of the three types.
The opponent-process theory of color vision suggests that in addition to the color-sensitive cones, we also
have neurons that respond to opponent colors (for example, red-green, blue-yellow). One neuron in an
opponent pair fires when one is looking at the red, for example, but is inactive when one is looking at green.
Both the trichromatic and opponent-process theories clarify different aspects of color vision, as color
perception occurs in the light-sensing cones in the retina and in the opponent cells serving the brain.
4. It’s dark in your house, and you are struggling to see what time it is without turning on the light. You notice
that if you turn your gaze slightly to the side of your watch, you can make out the large numbers. The ability to
see these large details in the dark is due to your:
a. presbyopia.
b. optic disc.
c. cones.
d. rods.
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Hearing: Part 1
Audition: Sense of hearing
Sound waves: Alternating zones of high and low pressure
moving through the environment
Qualities of sound
 Loudness
 Pitch
 Timbre
During toddlerhood, the triplets were diagnosed with
deafness and vertigo. Both conditions arose from
deterioration of inner ear and dated back to antibiotics
given during the first weeks of their premature lives.
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DECIBELS AND DAMAGE
 Loudness is measured in decibels (dB). The absolute
threshold for human hearing—the softest sound a
human can hear—is described as 0 dB.
 Loud noises, such as the 140 dB produced by a jet
engine, cause immediate nerve damage leading to
hearing loss.
 Chronic exposure to moderately loud noise, such as
traffic or an MP3 player near maximum volume, can
also cause damage.
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Qualities of Sound
Pitch
Timbre
 Degree to which a sound is high
or low determined by frequency
of its sound wave
 Number of sound waves passing
a given point per second; higher
frequency is perceived as higher
pitch, and lower frequency is
perceived as lower pitch
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Physically Out of Tune
POOR MUSCLE CONTROL, NOT AURAL PERCEPTION, UNDERLIES MOST CASES OF BAD
SINGING
 Recent research suggests that non-musicians could adjust an instrument to
match a specific note, but had trouble imitating the same note with their
voice.
 It was suspected that poor vocal muscle motor control was partly to blame.
Almost anyone can learn to sing!
Lena Groeger. Reproduced with permission. Copyright © 2012 Scientific American, a
division of Nature America, Inc. All rights reserved.
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Hearing: Part 2
Coming to terms with terms
 Eardrum: Membrane which separates outer from inner ear
 Hammer, anvil, stirrup: Bones in middle ear
 Oval window: Membrane leading to inner ear
 Cochlea: Primary component of inner ear; contains auditory receptors
 Basilar membrane: Hair receptor cells for sound waves
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TRANSFORMING SOUND WAVES INTO THE LANGUAGE OF THE BRAIN
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COCHLEAR IMPLANTS
This x-ray shows the cochlear implant’s electrode array
coiling into the cochlea, directly reaching nerve fibers
leading to the auditory nerve.
Hearing is enabled by circumventing damaged parts of the
inner ear. An external microphone gathers sound, which is
organized by a speech processor. Internally, an implanted
receiver converts this signal into electrical impulses that
directly stimulate the auditory nerve.
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Controversies
CONFLICTED FEELINGS ABOUT COCHLEAR IMPLANTS
 The deaf community is divided about cochlear implants.
 Not everyone thinks this device is a miracle.
 Some view deafness as a gift and would not change.
Would you seek a cochlear implant for your own young child? Why? Why
not?
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All Ears
DISTINGUISHING BETWEEN SOUND WAVES OF HIGH AND LOW
FREQUENCIES
Place theory
 Pitch corresponds to the location of the vibrating hair cells along the
cochlea.
Frequency theory
 Pitch is determined by the vibrating frequency of the sound wave,
basilar membrane, and associated neural impulses.
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All Ears: Pitch and The Cochlea
Volley principle
 Perception of pitches between 400 and 4000 Hz is made possible by
neurons working together to fire in volleys.
 Sum of all the groups firing, one after another, allows for frequency of
their firing to result in perception of the pitch of the sound.
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I CAN’T HEAR YOU
 Hearing loss is common.
 Damage to hair cells or auditory nerve lead to
sensorineural deafness.
 Damage to eardrum or middle-ear bones cause
conduction hearing impairment.
 Sound does not need to be earsplitting to do
damage.
 Next time you use your earbuds, remember
long-term exposure to loud music can cause
hearing damage!
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Show What You Know: Part 5
1. The pitch of a sound is based on the _____ of its waves.
a. frequency
b. timbre
c. amplitude
d. purity
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Show What You Know: Part 6
2. When a sound wave hits the eardrum, it causes vibrations in the bones of the
middle ear, making the fluid in the cochlea vibrate.
Hair cells on the basilar membrane bend in response to the motion, causing nerve
cells to fire. This process is known as:
a. the volley principle.
b. transduction.
c. the frequency theory.
d. audition.
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Show What You Know: Part 7
3. A researcher studying the location of neural activity in the cochlea finds that hair cells nearest
the oval window vibrate more to high-frequency sounds. This supports the place theory of pitch
perception.
4. The mechanisms underlying how we sense the pitch of a sound are complicated. We have
included two theories and one principle to explain pitch sensation. Try to solidify your
understanding of how we hear pitch by creating a sketch of the process.
Diagrams will vary. The pitch of a sound is determined by the frequency of its sound wave, which
is usually measured in Hertz. Place theory suggests that the location of neutral activity along the
cochlea allows us to sense different pitches of high-frequency sounds. Frequency theory
suggests that the pitch of sound is determined by the vibrating frequency of the sound wave,
basilar membrane, and associated neural impulses. Place theory explains our perception of
pitches from 4,000 to 20,000 Hz, and frequency theory explains how we perceive the pitch of
sounds from 20 to 400 Hz. The valley principle explains the perception of pitches from 400 to
4,000 Hz.
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Smell, Taste, Touch: The Chemical and Skin Senses – Part 1
SMELL: NOSING AROUND
Olfaction
 Sense of smell
Chemical sense
 Involve sensing odor molecules in currents of air
Olfactory epithelium
 Site of receptor neurons for odor molecules
Even without sight, Zoe is able to recognize her mother’s
scent from 15 feet in an outdoor setting.
How does she do this?
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Olfaction
 When enough odor molecules attach to an
olfactory receptor neuron, it fires, sending a
message to the olfactory bulb in the brain.
 Glomeruli then communicate the signal to the
higher brain centers.
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OLFACTION AND THE BRAIN
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Olfactory receptor neurons stimulate the olfactory bulb and converge with similar
neurons in clusters called glomeruli.
Higher brain centers are signaled on a fast track to the limbic system.
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Didn’t See That Coming
Some research suggests that ambient odors can sway
customer perceptions of stores and products.
 Upscale hotels: Lavender, white tea, citrus
 Clothing stores: Gender congruent scents
 Dentist office: Orange essence
Does this make scents to you?
THE SCENT OF MONEY
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Smell, Taste, Touch: The Chemical and Skin Senses – Part 2
TASTE: JUST EAT IT
Gustation refers to the ability to detect five basic tastes: Sweet, salty, sour,
bitter, and umami.
Tasting
Taste buds located in the papillae are made up of receptor cells that
communicate signals to the brain when stimulated by chemicals from
food and other substances.
Let’s take a closer look.
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TASTING
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Smell, Taste, Touch: The Chemical and Skin Senses – Part 3
Evolution and taste
 Evolutionary advantages
 Individual preferences
Touch and skin
 Epidermis
 Data collection mechanisms
 Thermoreceptors
 Pacinian corpuscles
 Meissner’s corpuscles
Zoe approaches eating in a very tactile way, digging in and
feeling the food on her skin. her senses of smell, taste, and
touch are extremely fine-tuned.
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TOUCH
The sensation of touch begins with our skin, which houses a variety of
receptors including those shown above.
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Brain Freeze Explained
COLD DRINKS CAUSE A MAJOR ARTERY IN THE SKULL TO DILATE.
 Researchers at Harvard Medical School found that the brain’s major
artery widens to infuse blood and protect the brain from extreme cold.
At the same time, increased pressure inside the skull may cause the
pain known as “brain freeze.”
Anybody for a snow cone?
 Stephani Sutherland. Reproduced with permission. Copyright © 2012
Scientific American, a division of NatureAmerica, Inc. All rights
reserved.
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Pain
Pain pathways
 Fast pain pathways
 Pain location
 Slow pain pathways
 Pain information―often with emotion
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Smell, Taste, Touch: The Chemical and Skin Senses – Part 4
Pain: Biopsychosocial perspective
 Biological factors
 Psychological factors
 Social factors
Gate control theory
 Perception of pain is increased or decreased by how brain interprets
pain through interaction of biopsychosocial factors.
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Smell, Taste, Touch: The Chemical and Skin Senses – Part 5
PAIN
Psychology of pain
 Negative feelings can amplify pain; laugher and distractions can soften
it.
Phantom limb pain
 Intense pain in amputated limb
Causes: Theories
 Changes in structure of neurons
 Reorganization of brain in relation to sensations felt in different parts
of body
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Smell, Taste, Touch: The Chemical and Skin Senses – Part 6
KINESTHESIA
 Kinesthesia enabled this stuntman to cross
Niagara Falls.
 What roles did his proprioception and
vestibular sense play?
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Show What You Know: Part 8
1. The chemical sense called olfaction provides the sensation of smell.
2. Chemicals from food that is being eaten are released in saliva, where they dissolve
and bathe the taste buds in your mouth. The chemicals find matching receptors and
latch on, sparking action potentials. This is an example of:
a. olfaction.
b. transduction.
c. sensory adaptation.
d. thermoreceptors.
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Show What You Know: Part 9
3. Describe the common features and characteristics of smell, taste, and touch.
Smell, taste, and touch all include the sensing of information in the environment through receptor cells
designed to detect a particular kind of stimuli. These three senses also involve transduction, which is the
process of transforming stimuli into neural signals. Neural signals for all three senses then are processed
by the central nervous system. Smell and taste are considered chemical senses, as they both involve
sensing chemicals (odor molecules for olfaction, flavor molecules for taste) in the environment. Taste and
touch relay data through the thalamus before going to higher brain centers, whereas olfaction is not
relayed through the thalamus.
4. Maya consulted her physician about severe back pain. In order to help her understand pain perception,
her doctor recommended she consider ________ , which suggests that the interpretation of pain can
either increase or decrease the perception of pain through an interaction of biopsychosocial factors.
a. the theory of evolution
b. an absolute threshold
c. the gate-control theory
d. gustation
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Perception: A Quick Review
Sensation
 Data-based processing
Perception
 Knowledge-based processing
When your friend texts you a smiley face, your brain sees
two dots, a hyphen, and a parenthesis. But how does it
know what these symbols mean collectively? Through
knowledge-based processing, you draw on past experience
to make sense of the new information you encounter.
LOL :-)
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THE MÜLLER-LYER ILLUSION
Which line looks longer? They are actually the same length. Visual depth
cues cause you to perceive that (b) and (d) are longer because it appears
farther away.
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Perception: Perceptual Organization
Gestalt psychology
 Initially interested in perception as result of noticing motion illusions
 Suggested that whole is greater than sum of parts: Brain naturally
organizes stimuli in their entirety rather than perceiving the parts and
pieces
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Perception: Part 1
PERCEPTUAL ORGANIZATION
Gestalt organizational principles
 Figure-ground
 Proximity
 Similarity
 Connectedness
 Closure
 Continuity
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Gestalt Organizing Principles: The Whole is Greater
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Perception: Depth Perception
Visual cliff
 A baby appears distressed when he encounters the
visual cliff, a supportive glass surface positioned over a
drop-off, or “cliff.” Most babies will not proceed, even
when coaxed by a trusted caregiver.
 This finding suggests that depth perception is already in
place by the time a child is crawling
So what do you think?
Is depth perception innate or learned?
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Perception: Part 2
DEPTH PERCEPTION
Convergence
 A binocular cue used to judge distance and depth based on the tension of the
muscles that direct where the eyes are focusing.
Retinal disparity
 A binocular cue that uses difference between the images the two eyes see to
determine the distance of objects
Binocular cues
 Information gathered from both eyes to help judge depth and distance.
Monocular cues
 Depth and distance cues that require the use of only one eye.
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Perception: Part 3
What is perceptual constancy?
Even when angle, lighting, and distance change, we know through
experience that objects do not change in shape, size, or color although
the sensory data might tell us otherwise.
Why is this important?
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SHAPE CONSTANCY
How do you know that all these doors are the same size and shape? The images projected
onto your retina suggest that the closing doors are narrower, nonrectangular shapes.
Your brain, however, knows from experience that all the doors are identical rectangles.
This phenomenon is known as shape constancy.
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Perception: Part 4
PERCEPTUAL SET
 Tendency to perceive stimuli in a specific
manner based on past experiences and
expectations
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Think Again
EXTRASENSORY PERCEPTION
 There is no scientific evidence to support the existence of ESP.
 Bem published research that demonstrated human ability to predict the future. His
statistical analysis was questioned and his work could not be replicated.
 Psychologists might call reports of ESP an illusory correlation.
Do you know why?
What do you think about the validity of ESP?
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Mother and Daughters
 Liz and her eldest daughter Sarah (back left)
relax with the triplets: Zoe (front left), Emma
(front right), and Sophie (back right).
 Zoe and Emma currently attend the Texas
School for the Blind and Visually Impaired,
while Sophie goes to middle school in the local
district.
Copyright © Macmillan education 2015
Show What You Know: Part 10
1.Perceptual constancy occur when perceptions are incongruent with real sensory
data.
2. One binocular cue called convergence is based on the brain’s interpretation of the
tension in muscles of the eyes.
a. convergence
b. retinal disparity
c. interposition
d. relative size
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Show What You Know: Part 11
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3. Using what you have learned so far in the textbook, how would you try to
convince a friend that extrasensory perception does not exist?
ESP is the purported ability to obtain information about the world in the absence
of sensory stimuli. There is a lack of evidence to support the evidence of ESP, and
most so-called evidence comes in the form of personal anecdotes. Subjective
information can be biased. Using critical thinking, we must determine the
credibility of the source and validity of the evidence. Despite ESP’s lack of scientific
credibility, many people still believe in its existence in part because of illusory
correlations, which appear to be links between variables that are not closely
related at all.
Copyright © Macmillan education 2015
Show What You Know: Part 12
4. Have you ever noticed how the shape of a door seems to change as it opens and
closes, yet you know its shape remains the same? This _____ refers to the fact that
even though stimuli may change, we know that objects do not change in shape, size,
or color.
a. perceptual set
b. perceptual constancy
c. convergence
d. texture-gradient
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