2. What we’ll sense and perceive…
in this chapter:
Sense:
especially vision and hearing
smell, taste, touch, pain, and
awareness of body position
How do the sense organs and
nervous system handle incoming
sensory information?
How does the brain turn sensory
information into perceptions?
Why is our style of creating
perceptions better at perceiving
the real world than at decoding
tricky optical illusions?
3. Basic Principles of
Sensation and
Perception
Your brain will interpret, perceive
these topics as they enter your
sense organs:
Sensation vs. Perception, Bottom-
Up vs. Top-Down Processing
Transduction and Thresholds
Sensory Adaptation
Perceptual Set
Context Effects on perception
Emotion/Motivation effects
4. Sensation vs. Perception
“The process by which our
sensory receptors and
nervous system receive and
represent stimulus energies
from our environment.”
“The process of organizing
and interpreting sensory
information, enabling us
to recognize meaningful
objects and events.”
The brain
receives input
from the
sensory organs.
The brain makes
sense out of the
input from
sensory organs.
Sensation Perception
5. Making sense of the world
What am I
seeing?
Is that
something I’ve
seen before?
Bottom-up
processing:
taking sensory
information and
then assembling
and integrating it
Top-down
processing:
using
models, ideas, and
expectations to
interpret sensory
information
6. Do you see a
painting or a 3D
bottle?
What’s on the
bottle?
Kids see eight to
ten dolphins.
Why do you think
kids see
something
different than
adults?
7. Top-down
Processing
You may start
to see
something in
this picture if
we give your
brain some
concepts to
apply:
“tree”
“sidewalk”
“dog”
“Dalmatian”
8. From Sensory Organs to the Brain
The process of sensation can
be seen as three steps:
Reception--
the stimulation
of sensory
receptor cells by
energy
(sound, light, he
at, etc)
Transduction--
transforming
this cell
stimulation into
neural impulses
Transmission--
delivering this
neural
information to
the brain to be
processed
9. Thresholds
The absolute threshold: the
minimum level of stimulus
intensity needed to detect a
stimulus half the time.
Anything below this
threshold is considered
“subliminal.”
10. When Absolute Thresholds
are not Absolute
10
Signal detection theory
refers to whether or not we
detect a stimulus, especially
amidst background noise.
This depends not just on
intensity of the stimulus but
on psychological factors
such as the person’s
experience, expectations, m
otivations, and alertness.
11. Subliminal Detection
Although we cannot learn complex
knowledge from subliminal
stimuli, we can be primed, and this
will affect our subsequent choices.
We may look longer at the side of
the paper which had just showed a
nude image for an instant.
Subliminal:
below our threshold for
being able to consciously
detect a stimulus
12. Difference threshold: the minimum difference (in
color, pitch, weight, temperature, etc) for a person to
be able to detect the difference half the time.
Weber’s law refers to the principle that for two
stimuli to be perceived as different, they must differ
by a minimum percentage:
2 percent of weight
8 percent of light intensity
0.3 percent of sound wave frequency to notice a
difference in pitch.
Any changes noticeable on this slide?
The “Just Noticeable Difference”
13. To help detect novelty in our
surroundings, our senses
tune out a constant stimulus,
such as:
a rock in your shoe
the ticking of a clock
If you concentrate on
keeping your eyes in one
spot, you’ll see the effects,
as your eyes adjust to stimuli
Visual sensory adaptation
will be tested when
discussing opponent-process
theory.
Sensory Adaptation
14. Perceptual Set
Perceptual set is what we expect to see, which influences
what we do see.
Perceptual set is an example of top-down processing .
Loch Ness monster
or a tree branch?
Flying saucers
or clouds?
16. Context Effect on Perception
Spelling test answers:
In which picture does the center dot look larger?
Perception of size depends on context.
Did context affect which word you wrote?
apple payor payee pairdouble pear
17. Effect of Emotion, Physical State, and
Motivation on Perception
Experiments show that:
destinations seem farther
when you’re tired.
a target looks farther
when your crossbow is
heavier.
a hill looks steeper with a
heavy backpack, or after
sad music, or when
walking alone.
something you desire
looks closer.
18. Vision, and Perceptual Organization
and Interpretation
And: ESP, Perception without Sensation
Vision (Sensation):
The Eye
From light input to mental
images
Retina and Receptors
Feature Detection
Parallel Processing
Color Vision
Visual Organization:
Form, Depth, and Motion
Perception
Size, Shape, and Color
Constancy
Visual Interpretation:
Restored Vision
Perceptual Adaptation
Topics we’ll be looking into:
19. The
Visible
Spectrum
We encounter waves
of electromagnetic
radiation.
Our eyes respond to
some of these waves.
Our brain turns these
energy wave
sensations into colors.
Vision:
Energy, Sensation, a
nd Perception
20. Color/Hue and
Brightness
We perceive the
wavelength/frequency of
the electromagnetic
waves as color, or hue.
We perceive the
height/amplitude of
these waves as
intensity, or
brightness.
21. Light from the candle passes through the cornea and the
pupil, and gets focused and inverted by the lens. The
light then lands on the retina, where it begins the
process of transduction into neural impulses to be sent
out through the optic nerve.
The lens is not rigid; it can perform accommodation by
changing shape to focus on near or far objects.
The Eye
23. The Blind
Spot
There is an area of missing information
in our field of vision known as the blind
spot. This occurs because the eye has no
receptor cells at the place where the
optic nerve leaves the eye.
To test this, walk slowly up to the screen
with one eye closed and the other eye
fixed on the dot, and one of the phones
will disappear.
24. Photoreceptors: Rods and Cones
When light reaches the back of the retina, it triggers
chemical changes in two types of receptor cells:
Rods help us see the black and white actions in our
peripheral view and in the dark.
Cones help us see sharp colorful details in bright light.
25. Visual Information Processing
The images we
“see” are not
made of light;
they are made of
neural signals
which can be
produced even
by pressure on
the eyeball.
The rods and cones send messages to ganglion and
bipolar cells and on to the optic nerve.
Once neural signals enter the optic nerve, they are sent
through the thalamus to the visual cortex.
26. Turning Neural Signals into Images
In the visual cortex are neurons called feature
detectors: they respond to certain visual aspects of
the environment.
These cells in turn send information to neural
networks (supercell clusters) that can perform tasks
such as recognizing individual faces.
Faces
Houses
Chairs
Houses and Chairs
Feature detection areas
27. Parallel Processing
Turning light into the mental act of seeing:
light waveschemical reactionsneural impulsesfeaturesobjects
and one more step...
Parallel processing: building perceptions out of sensory
details processed simultaneously in different areas of the
brain. For example, a flying bird is processed as:
29. Color Vision
Young-Helmholtz Trichromatic
(Three-Color) Theory
According to this theory, there are
three types of color receptor
cones--red, green, and blue. All the
colors we perceive are created by
light waves stimulating
combinations of these cones.
30. Color Blindness
People missing red cones or green
cones have trouble differentiating red
from green, and thus have trouble
reading the numbers to the right.
Opponent-process theory refers to
the neural process of perceiving white
as the opposite of perceiving black;
similarly, yellow vs. blue, and red vs.
green are opponent processes.
32. Turning light waves into mental images/movies...
Visual Perceptual Organization
We have perceptual processes for enabling us to
organize perceived colors and lines into objects:
grouping incomplete parts into gestalt wholes
seeing figures standing out against background
perceiving form and depth
keeping a sense of shape, size, and color constancy
despite changes in visual information
using experience to guide visual interpretation
Restored vision and sensory restriction
Perceptual adaptation
33. The Role of
Perception
Our senses take in the blue
information on the right.
However, our perceptual
processes turn this into:
1. a white paper with blue
circle dots, with a cube
floating in front.
2. a white paper with blue
circle holes, through
which you can see a
cube.
3. a cube sticking out to
the top left, or bottom
right.
4. blue dots (what cube?)
with angled lines inside.
34. Figure-Ground Perception
In most visual scenes, we pick out objects and figures,
standing out against a background.
Some art muddles this ability by giving us two equal
choices about what is figure and what is “ground”:
Stepping
man, or
Goblet or two
faces?
35. Grouping: How We Make Gestalts
“Gestalt” refers to a meaningful
pattern/configuration, forming a “whole” that is more than
the sum of its parts.
Three of the ways we group visual information into
“wholes” are proximity, continuity, and closure.
37. Visual Cliff: A Test of Depth Perception
Babies seem to develop this ability at crawling age.
Even newborn animals fear the perceived cliff.
38. Perceiving Depth: Binocular Methods
Unlike other animals, humans have
two eyes in the front of our head.
This gives us retinal disparity; the
two eyes have slightly different
views. The more different the views
are, the closer the object must be.
This is used in 3D movies to create
the illusion of depth, as each eye
gets a different view of “close”
objects.
How do we perceive depth
from a 2D image?...
by using monocular (needing
only one eye) cues
40. Monocular Cue:
Relative Size
We intuitively know to
interpret familiar objects (of
known size) as farther away
when they appear smaller.
41. Monocular Cues:
Linear Perspective and Interposition
The flowers in the
distance seem
farther away
because the rows
converge. Our
brain reads this as
a sign of distance.
42. Tricks Using
Linear
Perspective
These two
red lines
meet the
retina as
being the
same size
However, our
perception of
distance
affects our
perception of
length.
43. Monocular Cue: Relative Height
We tend to perceive
the higher part of a
scene as farther away.
This scene can look like
layers of
buildings, with the
highest part of the
picture as the sky.
If we flip the
picture, then the black
part can seem like
night sky… because it is
now highest in the
picture.
44. Monocular Cues: Shading Effects
Shading helps our
perception of
depth.
Does the middle
circle bulge out or
curve inward?
How about now?
46. Monocular Cues: Relative Motion
When we are
moving, we can tell
which objects are
farther away because it
takes longer to pass
them.
A picture of a moon on
a sign would zip behind
us, but the actual moon
is too far for us to pass.
47. Perceptual Constancy
Our ability to see objects as appearing the same
even under different lighting conditions, at
different distances and angles, is called
perceptual constancy. Perceptual constancy is a
top-down process.
Examples:
color and brightness constancy
shape and size constancy
48. Color Constancy
This ability to see a
consistent color in changing
illumination helps us see
the three sides as all being
yellow, because our brain
compensates for shading.
As a result, we interpret
three same-color blue
dots, with shades that are
not adjusted for shading, as
being of three different
colors.
49. Brightness Constancy
On this screen, squares A
and B are exactly the
same shade of gray.
You can see this when
you connect them.
So why does B look
lighter?
50. Shape Constancy
Shape constancy refers to the ability to perceive objects
as having a constant shape despite receiving different
sensory images. This helps us see the door as a
rectangle as it opens. Because of this, we may think the
red shapes on screen are also rectangles.
51. Size Constancy
We have an ability to use distance-related context
cues to help us see objects as the same size even if
the image on the retina becomes smaller.
The Ames room was invented by American
ophthalmologist Adelbert Ames, Jr. in 1934.
The Ames room was designed to manipulate distance
cues to make two same-sized girls appear very
different in size.
52. Visual Interpretation: Restored vision, sensory restriction
Experience shapes our visual perception
People have grown up without vision
but then have surgically gained sight
in adulthood. They learned to
interpret depth, motion, and figure-
ground distinctions, but could not
differentiate shapes or even faces.
Animals raised at an early age with
restrictions, e.g. without seeing
horizontal lines, later seem unable to
learn to perceive such lines.
We must practice our perception skills
during a critical period of
development, or these skills may not
develop.
Being blind between
ages 3 and 46 cost
Mike his ability to
learn individual faces.
53. Perceptual Adaptation
After our sensory
information is
distorted, such as by a
new pair of glasses or by
delayed audio on a
television, humans may
at first be disoriented but
can learn to adjust and
function.
This man could learn
eventually to fly an
airplane wearing these
unusual goggles, but
here, at first, he is
disoriented by having his
world turned upside
down.
54. The Nonvisual Senses
There’s more to Sensation and
Perception than meets the eye
Hearing: From sound to ear to
perceiving pitch and locating sounds.
Touch and Pain sensation and
perception
Taste and Smell
Perception of Body Position and
Movement
55. Hearing How do we take a
sensation based on sound
waves and turn it into
perceptions of
music, people, and
actions?
How do we distinguish
among thousands of
pitches and voices?
56. Hearing/Audition: Starting with Sound
Height or
intensity of
sound wave;
perceived as
loud and soft
(volume)
Perceived as
sound quality
or resonance
Length of the
sound wave;
perceived as
high and low
sounds
(pitch)
57. Sound Waves Reach The Ear
The outer ear
collects sound
and funnels it
to the eardrum.
In the middle ear, the sound waves hit
the eardrum and move the
hammer, anvil, and stirrup in ways that
amplify the vibrations. The stirrup
then sends these vibrations to the oval
window of the cochlea.
In the inner
ear, waves of fluid
move from the
oval window over
the cochlea’s
“hair” receptor
cells. These cells
send signals
through the
auditory nerves to
the temporal lobe
of the brain.
58. The Middle and Inner Ear
Conduction Hearing Loss:
when the middle ear isn’t
conducting sound well to the
cochlea
Sensorineural Hearing Loss:
when the receptor cells aren’t
sending messages through the
auditory nerves
59. Preventing
Hearing Loss
Exposure to sounds that
are too loud to talk over
can cause damage to
the inner ear, especially
the hair cells.
Structures of the middle
and inner ear can also
be damaged by disease.
Prevention methods
include limiting
exposure to noises over
85 decibels and treating
ear infections.
60. Treating Hearing Loss
People with conduction
hearing loss may be helped
by hearing aids. These aids
amplify sounds striking the
eardrum, ideally amplifying
only softer sounds or
higher frequencies.
People with sensorineural
hearing loss can benefit
from a cochlear implant.
The implant does the work
of the hair cells in
translating sound waves
into electrical signals to be
sent to the brain.
61. Loudness refers to
more intense sound
vibrations. This
causes a greater
number of hair cells
to send signals to
the brain.
Soft sounds only
activate certain hair
cells; louder sounds
move those hair
cells AND their
neighbors.
Sound Perception: Loudness
62. Sound Perception: Pitch
Frequency theory
At low sound frequencies, hair
cells send signals at whatever
rate the sound is received.
Place theory
At high sound frequencies,
signals are generated at
different locations in the
cochlea, depending on pitch.
The brain reads pitch by
reading the location where the
signals are coming from.
How does the inner ear turn sound
frequency into neural frequency?
Volley Principle
At ultra high
frequencies, receptor cells fire in
succession, combing signals to
reach higher firing rates.
63. Sound Perception: Localization
How do we seem to know the location of the source
of a sound?
Sounds usually
reach one of our
ears sooner, and
with more
clarity, than they
reach the other
ear.
The brain uses this
difference to
generate a
perception of the
direction the
sound was coming
from.
64. Other Senses
We may not have all of the
sensory abilities of the shark
(such as sensing the electric
fields of others) or migratory
birds (such as orienting by the
earth’s magnetic field).
But we do have senses of:
smell and taste.
four different components of the sense of
touch.
body/kinesthetic awareness.
65. Touch
Touch is valuable…
for expressing
and sensing
feelings.
for sharing
affection, comfort
, and support.
for detecting the
environment in
multiple
ways, such as
pressure, warmth
, cold, and pain.
66. Four Components
of Touch
Stroking adjacent
pressure spots
creates a tickle.
Adjacent cold and
pressure sensations
feel wet.
Adjacent warm and
cold feels searing hot.
Warmth
PainCold
Pressure
67. Pain...what is it good for?
Pain tells the body
that something has
gone wrong. Pain
often warns of severe
injury, or even just to
shift positions in a
chair to keep blood
flowing.
Not being able to feel
pain, as in Ashley’s
case, means not being
able to tell when we
are injured, sick, or
causing damage to
our bodies.
68. Biological Factors in Pain Perception:
The Pain Circuit
Nociceptors are sensory receptors whose
signals are interpreted by the brain as pain.
The pain circuit
refers to signals
that travel to the
spinal cord, up
through small
nerve
fibers, which then
conduct pain
signals to the
brain.
69. Gate-Control Theory
This theory hypothesizes that the spinal cord contains a
neurological “gate” that blocks pain signals or allows
them to pass on to the brain. Stimulating large nerve
fibers in the spinal cord through
acupuncture, massage, or electrical stimulation seems
to close that gate.
Endorphins
These hormones can be released by the body to reduce
pain perception.
Phantom Limb Sensation
As the brain produces false sounds (tinnitus, ear
ringing) and sights (aura, lights with migraines), it can
produce pain or other perception of amputated/missing
arms or legs.
Biological Factors in Pain Perception
70. Psychological Influences on Pain
Distraction, such as
during intense
athletic competition,
can limit the
experience of pain.
Pain and Memory
Memories of pain
focus on peak
moments more
than duration.
Tapered pain is
recalled as less
painful than
abruptly-ended
pain.
71. Social and Cultural Influences
on Pain Perception
Social contagion
We feel more pain if other people are experiencing
pain. This occurs either out of
empathy/mirroring, or a shared belief that an
experience is painful.
Cultural influences
We may not pay attention as much to pain if we
see a high level of pain endurance as the norm for
our family, peer group, or culture.
72. Controlling/Managing/Reducing Pain
Pain can be reduced through drugs, acupuncture, electrical
stimulation, exercise, hypnosis, surgery, relaxation
training, and distraction.
Even the placebo effect has real influence on pain
perception. When we think we are taking pain killers or
receiving acupuncture, our bodies can release endorphins.
Distraction with virtual reality immersion (below) has
helped burn victims manage intense pain.
75. Neurochemistry of Taste
There are no regions of the tongue,
just different types of taste
receptor cells projecting hairs into
each taste bud’s pore.
These cells are easily triggered to
send messages to the temporal
lobe of the brain.
Burn your tongue? Receptors
reproduce every week or two. But
with age, taste buds become less
numerous and less sensitive.
Top-down processes still can
override the neurochemistry;
expectations do influence taste.
76. Smell: Odor Receptors
Humans have a poor sense of smell for an animal. Even
so, humans have 350 different types of smell receptors
allowing us to detect about 10,000 different odors.
77. Smell: The Shortcut Sense
Sensations of smell take a
shortcut to the
brain, skipping the trip
through the “sensory
switchboard” (thalamus)
made by all the other
senses.
Information from the nose
goes not only to the
temporal lobe but also to
the limbic
system, influencing
memory and emotion.
Smell links lovers, parent
and child, and other
creatures to each other
78. Sensing Body Position and Movement
Kinesthesis (“movement
feeling”): sensing the
movement and position of
individual body parts relative
to each other.
How it works: sensors in the
joints and muscles send
signals that coordinate with
signals from the
skin, eyes, and ears
Without kinesthesis, we
would need to watch our
limbs constantly to
coordinate movement.
79. Sensing Body Position and Movement
Vestibular sense: the ability to sense
the position of the head and body
relative to gravity, including the sense
of balance.
How it works: fluid-filled chambers in
the inner ear (vestibular sacs and
semicircular canals) have hairlike
receptors that send messages about
the head’s position to the cerebellum
Vestibular sense serves as the human
gyroscope, helping us to balance and
stay upright.
80. Mixing the different senses together
Sensory interaction occurs
when different senses
influence each other.
For example:
a burst of sound makes a
dim light source more
visible.
flavor is an experience not
only of taste, but also of
smell and texture.
seeing text or lip
movement, or even
feeling the puff of air from
consonants, affects what
words we hear.
456789
Synaesthesia is a condition
when perception in one
sense is triggered by a
sensation in a DIFFERENT
sense.
Some people experience
synaesthesia all the
time, reporting that, “the
number 7 gives me a salty
taste” or “rock music seems
purple.”
81. Embodied Cognition
holding a warm mug promotes social warmth.
social rejection looks like pain reception in the brain.
words on a heavy clipboard seem… weighty.
being ignored (cold shoulder) makes a room seem
colder.
leaning left physically leaning left politically.
in a foul smelling room, people were more likely to
suspect bad intentions (foul play) by others.
It’s no coincidence that we use sensation words to describe
feelings. Studies seem to show that:
Embodied cognition refers to the effect of
body experience on feelings, attitudes,
thoughts, and judgments.
82. Extrasensory Perception (ESP)
Extrasensory Perception (ESP) can defined, literally, as
perception without sensation.
Believers in ESP think that it involves getting accurate
information directly to the mind, skipping the known
senses.
Types of ESP include:
telepathy (“reading” messages from other minds).
clairvoyance (“seeing” remote events).
precognition (“knowing” the future).
The evidence for ESP is anecdotal and controversial;
people seem to notice times when predictions come true
and perceptions match reality, but tend to disregard the
times when they do not.
Click to reveal shortened definition; click again to reveal rest of animation.
Click to reveal definitions for bottom-up and top-down processing.
Click to reveal answer and to circle the dolphins.Answer to the question: Top-down processing by children uses different experiences and different models; they are likely to have seen more images of dolphins than images of a nude embrace. Adults also do more top-down processing, and are more likely to “see” objects that aren’t fully there. This shows that “seeing” involves the process of perception, not just the process of our eyes taking in information.
Click to reveal sidebar and hints one by one.
Automatic animation.Psychophysics refers to the study of the psychological effects of the forms of energy (heat, light, sound) that we can detect.
No animation.Instructor: You could first present this question using a specific sense, such as “How loud does a sound have to be before you can detect it?”
No animation.For example, parents of newborns can detect a faint baby’s cry that for others would not stand out from background noise.
Click to reveal bullets and example.Research seems to show that: 1) we can sense something without being aware of it. 2) we can be briefly primed, but not enduringly influenced, by subliminal stimuli.
No text animation, but the background color on the right side of the screen changes very slightly (and slowly) a couple of times. Ask students to raise their hand if they see a difference in color in the background of this slide.On a click, you can change the color again, and another click changes it back to the original color.
Click to reveal bullets.To prepare for this slide, at the beginning of class you could ask students to tuck a pen behind one ear, and by the time they get to this slide, ask if they feel it.Or ask whether they feel the cell phone in their pockets, and then ask them to switch to the opposite pocket and see if they notice it more.
Click to reveal second picture.
Click to reveal second picture.Instructor: if you used this extra example, you can ask one half the class to focus on the image on the left, the other to look right. Then click and the ambiguous image appears, and the class can raise hands about which of the two images they see, to see if priming influenced their perception.
The text at the bottom of the screen will appear on click, and is mean to appear only AFTER you do the “spelling” test below. Instructor: The point of the test is to demonstrate how context, affected/primed by the previous word you stated, can affect which word they perceived.You can state to students, “Six word spelling test! You cannot ask questions; just take a guess and listen for the next word. Write these words down:Double. Pear. (Students may, if “double” gives them context, write “pair.”)Apple. Payor. (Students may, when primed by “apple”, write “pear.”)Payee. Pair. (Here, students might be confused, or some may write “payor.”)
Click to reveal bullets. After reading the last bullet, click again to zoom the banana split.
No animation.
No animation.
Click to reveal second illustration.
Click to reveal bullets.
Click to zoom cross section of retina. Click again to remove it.Instructor: You can point the sequence of what the retina does with light. The white arrows show light going in, triggering a reaction in the rods and cones (more about that in a couple of slides). The black arrows show neural impulses generated in the bipolar cells and gathered by the ganglion cells to be funneled into the optic nerve “pipeline” of nearly one million ganglion cell axons. That’s a lot of potential information that can be shipped to the brain! By comparison, the auditory nerve is made up of only ten thousand axons/fibers.
Click to reveal bullets.Instructor: you can ask students to speculate, “Why aren’t we aware of having a blind spot?” Answer: Our eyes keep moving so we don’t miss information; also, the brain fills in the missing information. Click to reveal activity. Based on the size of your screen and classroom, even if students walk up the center of the room from the back, none of the phones may appear to disappear, partly because it’s hard to keep the eye focused on the dot. However, students who have texts with them can open their books and use the example on page 229. See who can announce first: with the left eye closed, which car (or phone) should disappear?Answer: the one on the right.
Click to reveal bullets and example.Instructor: have students see if they can guess which objects in the picture are cones and which are rods; the shape implied by the names should be a big hint.
No animation.Instructor: the first bullet point can be demonstrated by the activity suggested on page 230 of the text (closing eyes, turning eyes to the left, pressing on the right corner of they eyelid). It can also be demonstrated by mentioning, “Maybe this is why people are said to “see stars” when they get punched hard in the head.”
Click to reveal bullets and example.Instructor: damage to these areas of the brain appears to make it difficult to see certain kinds of objects; most striking is those who have face blindness. Those with these conditions can often see the features, but not integrate them into a whole.
Click to reveal bullets and example.
No animation.
No animation.Instructor: you could start by saying that we see the color of an orange because it absorbs all light except the wavelengths that our brain interprets as orange.You could note that the red, green and blue don’t actually refer to the appearance of the cones; they are the colors to which these three cones react.
Click to reveal text boxes.Instructor: you could add, “Some people say that dogs have “black and white” vision. In fact, they are lacking red receptors, so their vision has simpler color perception, dichromatic, not monochromatic.”Feeling superior to animals? Note that many birds and insects can sense ultraviolet and infrared that you can’t see.
Instructor: Tell the students: “Stare at the center dot for 30 seconds; if you’re doing it well, the flag will start to disappear. If it does, keep staring at the dot.” Further narration as they stare at the dot: “If opponent-process theory is correct, then fatiguing our perception of one will make a blank slide look like the opposite color… and the opponent processes are white vs. black, red vs. green, and yellow vs. blue.” Click to make flag disappear.What do you see?Question for students: “Besides opponent-process theory, what else are we demonstrating here?”...(sensory adaptation).After our color receptors for green become fatigued, an empty white background will briefly seem red, just as plain water might taste salty or strange after eating a lot of intensely sweet candy to the point of fatiguing our tongue.There have been versions of this circulating online in which our receptors get fatigued just by some dots near the center dot, and a B&W picture turns to full color when we look at a blank space.
Click to reveal bullets.This is a summary slide for this upcoming section, listing the major concepts and not the section headings.
Click to reveal bullets, BUT before any bullets appear, see how many different visual perceptions students can come up with.To nudge the discussion, note the little ‘x’ near the center of the picture; ask if it looks like it’s inside a blue hole, or at the back and bottom of a cube that opens up and to the left…
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Click to show a different perspective on each image.Instructor: perhaps you can get students to bring out the definitions of the concepts in these pictures (as you click to reveal the animations).“Proximity” means we tend to see objects that are close together as being part of the same object.
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No animation.Instructor: see if students can notice one other monocular cue for depth perception evident in this picture...interposition. The flowers in the very front (bottom of the frame) partially block the view of other flowers, and the whole hill of flowers appears to block the view of the hill in the background.
Click to bring bottom line up.The way our brain changes the perception of length in this case is called the Ponzo illusion, first demonstrated by Italian psychologist Mario Ponzo in 1913.The two [rods/bars/logs] are the same size on screen, but our eyes tend to see one as larger because linear perspective makes its location on the train tracks seem farther away.
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Click to invert the image and show the hollow as a hill.
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No animation.A great animated example can be found at http://psych.hanover.edu/krantz/motionparallax/motionparallax.html.This depth perception cue is often referred to as motion parallax. It is used by many animals that don’t have the benefit of binocular cues because their eyes are on the sides of their heads. It is called “relative motion”; when we are moving, the objects we pass can appear to be moving in the opposite direction, and the farther objects don’t move as fast.
No animation.Instructor: you can use this narrative to tie things together after the definition--“Because this means perceiving sameness even when receiving different sensory information, this means that we use this top-down process to change what colors, shapes, sizes and objects we think we see, depending on the context.”
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Instructor: you could ask students an intentionally ambiguous question...“What shapes do you see outlined in red?” If they say “rectangle,” ask again, no longer referring to the doors. “Tell us the names of the red shapes.” Then click to fade the doors and reveal that the second and third red shapes are trapezoids.
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Click for Frequency sequence; click for Amplitude sequence.Amplitude, or loudness, is measured relative to the threshold for human hearing (set at zero decibels). The rustling of leaves you heard measures at about 20 decibels, my voice (and most conversation) measures at about 40 to 60 decibels. You’ll find out more about the decibels of common sounds a little later in this presentation, but here’s an important decibel tip: enough exposure to a sound above 85 decibels can cause hearing damage. Click for Complexity sequence.We distinguish the same note played by a piano and any other instrument due to the complexity of the sound wave and our perception of timbre. Each human voice has its own complexity; for instance, can you describe what it is about the voice of a friend that allows you to recognize that person on the phone? Of these properties, frequency provides most of the information we need to identify sounds. It is measured in cycles per second, or hertz (Hz), and perceived by humans as pitch (high and low sound). Both amplitude and frequency will be demonstrated further in the next slide.
Click to show details about outer, middle, and inner ear.
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Click to reveal bullets.Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as partial sound barrier, creating a “shadow” in which sounds are delayed and not as loud (and possibly missing some higher frequencies). Instructor: you could do an experiment showing that when sounds are directly behind or in front of us, it is harder to locate the sound. However, some people may have learned to use the shape of the ear to make even this distinction.
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Click to reveal bullets.At the other end of the perspective from people like Ashley are those who feel pain all the time, without proportional external stimulus to trigger it; they might even feel pain in limbs that aren’t there.
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Click to reveal bullets.Instructor: gate control might explain why scratching relieves an itch sensation, or why creams made from hot peppers relieve arthritis pain--they send a signal through the “gate” which blocks the pain signal to the brain.
Click to reveal bullets.Not mentioned in the book: some medication and meditation techniques allow people to reduce the anguish/suffering associated with pain, reducing pain to just another sensation to be noticed fleetingly.
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No animation.Instructor: this is a brief summary of biopsychosocial perspectives on pain experience and can be used as a summary at the end, or in place of the more detailed slides.
Click to show labels.Tastes may exist to attract humans to energy and protein-rich foods that are typically sweet or “umami,” and to avert them from potentially toxic or harmful substances that are often bitter or sour. Umami is a recently identified, savory taste that is associated with monosodium glutamate, meats, mushrooms, seaweed, and aged cheeses (such as Parmesan). Salty tastes also attract humans to replenish essential salts.
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Click to reveal bullets.Instructor: The final point on the slide links to two concepts from elsewhere in this course--falsely perceiving order in random events, and the availability heuristic.