Transcript Using POCS Method of Problem-Solving

CHAPTER 3
(Sensation and Perception)
Michael L. Farris
Psychology 101
Subliminal Persuasion
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Famous Attempt at Subliminal Advertising:
New Jersey theater
“Eat Popcorn” & “Drink Coca-Cola”
Words appeared for 1/3000 of a second every 5
seconds
– At that speed, they were below the normal
threshold for awareness.
– During the 6 weeks the messages ran, the firm
claimed increases in popcorn and Coca-Cola
sales.
– What do you think? Did the sales increase
because of the subliminal messages, or
something else?
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Please see pages 108, 117 & 118 in your text for more information.
Backmasking
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In another uproar over subliminal perception, critics charged that
spoken messages recorded backward (called “backmasking”) in rock
music are perceived unconsciously by listeners.
Queen (Another One Bites the Dust)
The Beatles (White Album)
Experiment: Vokey and Read recorded a variety of sentences
backward, including selections from Lewis Carrol’s
“Jabberwocky” and the 23rd Psalm from the Bible.
Their tests clearly showed that the backward sentences were
not recognized.
Still, shopping malls sometimes use subliminal messages
embedded in the music (“Don’t Steal”, “Buy More”, Orange
Julius Rules”)
Conclusion: There is little evidence that subliminal messages greatly
influence behavior. P.118.
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Sensitivity

Sensation: The incoming flow of information from the
environment. P.84.

Perception: The process by which the brain organizes
sensations into meaningful patterns or representations of
the world. (p.106)

Hearing is much more sensitive than taste
– A voice or musical instrument that is off pitch 1/3 of 1% will be
noticeable.
– For taste, a 20% change is necessary to produce a JUST
NOTICEABLE DIFFERENCE (p.84).
– If a cup of coffee has 5 teaspoons of sugar in it, 1 more (1/5 of
5) must be added before you would notice an increase in
sweetness.

Just Noticeable Difference: Any noticeable difference in a
stimulus.

Absolute Threshold: The minimum amount of physical energy
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necessary to produce a sensation.
Absolute Thresholds
Sensory Modality
Vision
Absolute Threshold
Candle flame seen at 30 miles on a clear, dark night
Hearing
Tick of watch under quiet conditions at 20 feet
Taste
1 teaspoon of sugar in 2 gallons of water
Smell
1 drop of perfume diffused into a three-room apartment
Touch
A bee’s wing falling on your cheek from 1 cm above
Please see pages 84-85 in your text for more information.
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Vision: The Human Eye
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Vision Problems (P.87-93)
The shape of the eye affects focusing.

Hyperopia (farsightedness): If the eye is too short, nearby
objects cannot be focused, but distant objects are clear.

Myopia (nearsightedness): If the eyeball is too long, the
image falls short of the retina, and distant objects cannot
be focused.

Astigmatism: When the cornea or the lens is misshapen,
part of the visual field will be focused, and part will be
fuzzy. In this case, the eye has more than one focal point.
All three visual defects can be corrected by placing glasses or contact lenses
in front of the eye. These added lenses change the path of incoming light to
restore crisp focusing.
As people age, the lens becomes less flexible and less able to accommodate.
Since the les must do its greatest bending to focus nearby objects, the result
is presbyopia, or farsightedness due to aging.
Perhaps you have seen a grandparent reading a newspaper at arm’s length
because of presbyopia. If you now wear glasses for farsightedness (myopia),
you may need bifocals as you age.
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(Unless your arms grow longer in the meantime.)
Accommodation

Accommodation (p.88): The process of adjusting
the configuration of the lenses to bring images
into focus on the retina.

Try the “cocktail sausage” demonstration. Hold
both index (pointer) fingers at arms length,
pointing at each other.

Leave a 6 inch gap, and focus on the wall through
the gap. Slowly bring the fingers together,
staring at the wall through the gap.

Stop just before your fingers touch. See the
sausage? Yum!
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Rods and Cones

Rods: Rod-shaped receptors in the retina which
predominate in low (dim) light conditions. Species active
only at night tend to have rod-only retinas. Peripheral vision
is mainly rod vision, and occurs at the edges of the visual
field. At night, the most visible color to our rods is blue or
blue-green. That’s why police use blue lights!

Cones: Receptors in the retina that predominate in good
(bright) lighting, and provide high-acuity (finely detailed)
colored perceptions of the world. In dim illumination, there
is not enough light to reliably excite the cones, and the
more sensitive rod-mediated vision predominates. The
most visible color to cones is yellowish green. That’s why
some fire trucks and roadside work crew vests are this
color!

An area at the center of the retina containing only cones is
called the Fovea.
Please see pages 88-89 in our text for more information.
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Color Blindness

A person who is color blind cannot perceive colors (the
world looks like a black and white movie). How do we
know?

In a few rare cases, people have been color blind in only
one eye and can compare.

Two colors of equal brightness look exactly alike to the
color blind individual.

The color blind person either lacks cones or has cones that do not
function normally.

Color blindness is caused by changes in the genes that control red,
green, and blue pigments in the cones.
Please see pages 92-93 in our text for more information.
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Are you colorblind?
Which numbers do you see?
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Colorblind Test
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If picture A looks like number 3, and picture B looks like
number 73, you're ok. If picture A looks like number 5 and
picture B looks like nothing at all, you may have a
deficiency in your color vision !

Red-green color blindness is a recessive, sex-linked trait. That
means it is carried on the X, or female, chromosome. Women
have two X chromosomes, so if they receive only one defective
color gene, they still have normal color vision.

Color blind men, however, have only one X chromosome,
so they can inherit the defect from their mothers (who are
usually not color blind themselves).

The red-green color blind person sees both reds and
greens as the same color, usually as a yellowish brown.
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Dark Adaptation
Dark Adaptation (Coon, p.170) is the dramatic increase in
retinal sensitivity to light that occurs in darkness.
If you enter a dark movie theatre on a sunny day, you
practically need to be led to your seat. After a short time,
however, you begin to see the entire room in detail.
Studies show that it takes about 30-35 minutes of complete
darkness to reach maximum visual sensitivity. A
completely dark-adapted eye is 100,000 times more
sensitive to light. At that point, the human eye is almost as
light sensitive as the eyes of an owl!
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Blind Spot

Blind Spot (pgs.89-90): The gap in the receptor
layer of the retina where the bundle of retinal
ganglion cell axons leave the eye. There are no
rods or cones where the optic nerve leaves the
eye.

One of the most dramatic experiments to perform is
the demonstration of the blind spot. The blind spot is
the area on the retina without receptors that respond
to light. Therefore an image that falls on this region
will NOT be seen. It is in this region that the optic
nerve exits the eye on its way to the brain. To find
your blind spot, look at the image below or draw it on
a piece of paper:
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Blind Spot Demonstration

To draw the blind spot tester on a piece of paper, make a
small dot on the left side separated by about 6-8 inches
from a small + on the right side.

Close your right eye. Hold the image (or place your head
from the computer monitor) about 20 inches away.

With your left eye, look at the +. Slowly bring the image (or
move your head) closer while looking at the +.

At a certain distance, the dot will disappear from sight...this
is when the dot falls on the blind spot of your retina.

Reverse the process. Close your left eye and look at the dot
with your right eye. Move the image slowly closer to you
and the + should disappear!
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Find Your Blind Spot!
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Complementary Colors
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Complementary colors: Pairs of colors that produce white or gray
when combined in equal measure (for example, red light and green
light).
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This is based on the opponent-process theory (Ewald Hering, 1878),
which observes that complementary colors cannot exist together
(there is no such thing as bluish yellow or reddish green).

Another observation is that the afterimage produced by staring at
yellow is blue and vice versa. Blue is the complementary color to
yellow. Red is complementary to green.
(For more information, please see page 58 in the Pinel text.)
A Demonstration follows with the next slide: Stare at the
center of the red box for 30 seconds (or a slow count of 30).
Then look at the next (blank) slide, or a white surface.
What do you see?
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Hearing

Any vibrating object (a tuning fork, the
string of a musical instrument, or the
vocal cords) will produce sound waves
(cyclic, wave-like movement of air
molecules).
 Other materials, such as fluids or solids,
can also carry sound. But sound does
NOT travel in a vacuum (p.94). Movies that
show characters reacting to the “roar” of
alien starships or titanic battles in deep
space are in error.
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How We Hear

The pinna (visible outer ear) funnels
sound to the tympanic membrane (ear
drum), which vibrates and moves three
small bones (auditory ossicles). These
bones link the eardrum with the cochlea.
 The cochlea (p.95), a snail shaped organ
that makes up the inner ear, is the organ
of hearing.
 There is fluid in the cochlea, and waves in
the fluid are detected by tiny hair cells,
which generate nerve impulses to be sent
to the brain. The bristles on hair cells,
called cilia, are sensitive to movement.
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Deafness

Conduction Deafness (p.97): Occurs when there is poor transfer
from the eardrum to the inner ear. The eardrum or ossicles may be
damaged or immobilized by disease or injury. Often, a hearing aid
will overcome conduction deafness.

Nerve Deafness (p.97): Results from damage to the hair cells or
auditory nerve. Hearing aids don’t help, because auditory
messages are blocked from reaching the brain. However, a new
type of artificial hearing system is being developed that may help.

Stimulation Deafness (p.97): Occurs when very loud sounds
damage hair cells in the cochlea. Each of us starts life with about
32,000 hair cells. However, we begin losing them the moment
we’re born. By age 65 more than 40% are gone.
– If you work in a noisy environment or enjoy loud music, motorcycling,
or similar pursuits, you (we!) may be risking stimulation deafness.
– Hair cells (which are about as thick as a cobweb) are very fragile and
easily damaged.
– Once dead, they are never replaced. When you abuse them, you lose
them.
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Hearing Loss
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The danger of hearing loss depends on both the loudness
of sound and how long you are exposed to it.

Daily exposure to 85 decibels or more may cause
permanent hearing loss.

Even short periods at 120 decibels (a rock concert) may
cause a temporary threshold shift (a partial, transitory loss
of hearing).

Brief exposure to 150 decibels (a jet airplane nearby) can
cause permanent deafness.
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Please see page 97 for more information on Hearing Loss.
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Decibel Levels of Common Sounds
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softest audible sound 0 dB
normal breathing 10 dB
rustling leaves20 dB
whispering25 dB
clothes dryer60 dB
normal conversation60 dB
dishwasher65 dB
car70 dB
busy traffic75 dB
alarm clock80 dB
noisy restaurant80 dB
average factory85 dB
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screaming child90 dB
subway train100 dB
diesel truck100 dB
jackhammer100 dB
helicopter105 dB
power mower105 dB
shouting in ear110 dB
live rock music90-130 dB
football stadium117 dB
band concert120 dB
thunder120 dB
car horn120 dB
jackhammer130 dB
air raid siren130 dB
noisy squeeze toys135 dB
PAIN STARTS 140 dB
gunshot140 dB
jet engine140 dB
rocket launching180 dB 24
loudest sound194 dB
Tinnitus

Tinnitus is a ringing or buzzing sensation following
exposure to loud sounds (Coon,p.176).

If you feel or hear this ringing or buzzing, chances are good
that hair cells have been damaged.

Almost everyone has tinnitus at times, especially with
increasing age. But after repeated sounds that produce
this warning, you can expect to become permanently hard
of hearing.
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A study of people who regularly went to amplified concerts
found that 44% had tinnitus and most had some hearing
loss (Meyer-Bisch, 1996).

The next time you are exposed to a very loud sound,
remember to take precautions against damage. (Earplugs
are good, and fingers are always handy in an emergency!)
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Smell and Taste (p.99)
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Olfaction: The sense of smell.

Gustation: The sense of taste.
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1 person out of 100 cannot smell anything at all! (Total anosmia)

Smell may seem like a minor sense that we can live without. Why
is this anosmia dangerous?

Smell and taste are very closely linked. One affects the other.
 Sensory Adaptation: Decreases our response to a constant or
unchanging stimulus (p. 86). This is why we can’t smell
something as well after a few minutes of being in a room with it.

Taste buds (the receptor organs for taste) are located mainly on
the top side of the tongue, but a few are found elsewhere inside
the mouth.
 There are 4 basic taste sensations:
– Sweet (least sensitive)
– Salt (a bit sensitive)
– Sour (sensitive)
– Bitter (most sensitive)
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Why might bitter and sour foods be most detectable?
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The Somesthetic Senses

A gymnast “flying” through a routine on the uneven bars
may rely as much on the somesthetic senses as on vision
(soma means “body”, esthetic means “feel”).

Somesthetic senses include:
– Skin senses (touch)
– Kinesthetic senses (receptors in the muscles and joints that
detect body position and movement)
– Vestibular senses (receptors in the inner ear for balance,
gravity and acceleration).
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Motion Sickness: You’ve probably seen astronauts on
television, playfully enjoying weightlessness. In reality, if
you were to ride into space, it is about 70% likely that you
would throw up! (p.104)
Space sickness is similar to sea-sickness, air-sickness, and
car-sickness. It is especially intense because
weightlessness drastically alters sensations the brain
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receives from the head, muscles, and joints.
Motion Sickness

Motion sickness is related to the vestibular system (p.104).

Fluid filled sacs in the vestibular system (called otolith organs) are
sensitive to movement, acceleration and gravity.

The otolith organs contain tiny crystals in a soft, gelatin-like mass.
The tug of gravity or rapid head movements can cause the mass
to shift. This stimulates hair-like receptor cells, allowing us to
sense gravity and movement through space.

The best explanation of motion sickness is the sensory conflict
theory (Coon, p.181): According to this theory, dizziness and
nausea occur when sensation from the vestibular system fail to
match information received from the eyes and body. On solid
ground, the information from the vestibular system, vision, and
kinesthesis usually matches. However, in a heaving, pitching
boat, car, or airplane, a serious mismatch can occur-causing
heaving of another kind.
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Selective Attention
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Selective Attention (p.106): Voluntarily focusing on a
specific sensory input.

Seat of the Pants Phenomenon: As you sit in class,
receptors for touch and pressure in the seat of your pants
are sending nerve impulses to your brain. Although these
sensations have been present all along, you were probably
not aware of them until just now. The “seat of the pants
phenomenon” is an example of selective attention.

The cocktail party effect: Another example of selective
attention. We are able to tune in on a single sensory
message (conversation) while excluding others. If you are
listening to one person intently, another person nearby can
talk backward and you will not notice the strange speech!
(Wood & Cowan, 1995)
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Sensory Gating of Pain

One type of pain will sometimes cancel another (p.103)

Gate Control Theory suggests that pain messages from different
nerve fibers pass through the same neural “gate” in the spinal
cord.

If the gate is “closed” by one pain message, other messages may
not be able to pass through.

Messages carried by large, fast nerve fibers seem to close the
spinal pain gate directly. Doing so can prevent slower, “reminding
system” pain from reaching the brain.

Pain clinics use this effect by applying a mild electrical current to
the skin. Such stimulation, felt only as a mild tingling, can greatly
reduce more agonizing pain.

Counterirritation (Coon, p.188): Using mild pain to block more
intense or long lasting pain. This explains why some of the oldest
pain control techniques work (applying ice packs, hot-water
bottles, mustard packs, vibration, or massage to other parts of the
body). Pinching yourself or digging nails into the flesh may help
at the dentist. Focus attention on the pain you are creating, and
increase its intensity anytime the dentist’s work becomes more
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painful. It works for many people, but not all.
Acupuncture
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Some researchers believe that gate control
theory explains the painkilling effects of
acupuncture (the Chinese medical art of relieving
pain and illness by inserting thin needles into the
body). P.103.

Acupuncture has an interesting side effect not
predicted by sensory gating. People given
acupuncture often report feelings of lightheadedness, relaxation, or euphoria. Why?

To combat pain, the brain causes the pituitary
gland to release painkilling chemicals called
endorphins. (Endo means “within”, orphin
means “opiate”). P.103.
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Chemically, endorphins are quite similar to
morphine.
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Pain & Beta-Endorphins

The painkilling effect of placebos (fake pills or injections) appears
to be based on a rise in endorphin levels (p.26).

A release of endorphins also seems to underlie “runner’s high”,
masochism, acupuncture, and the euphoria sometimes associated
with childbirth and painful initiation rites.

In each case, pain and stress cause the release of endorphins.
These in turn induce feelings of pleasure or euphoria similar to
morphine intoxication.

The “high” often felt by long-distance runners serves as a good
example of the endorphin effect. In one experiment, runners were
tested for pain tolerance. After running 1 mile, each was tested
again. In the second test, all could withstand pain about 70%
longer than before. The runners were then given naloxone, a drug
that blocks the effects of endorphins. Following another 1 mile
run, the subjects were re-tested. This time they had lost their
earlier protection from pain.

People who say they are “addicted” to running may be closer to 32
the truth than they realize.