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Sensation
and
Perception
PowerPoint®
Presentation
by Jim Foley
Chapter 6
What we’ll sense and perceive…
in this chapter:
 Sense:
 especially vision and hearing
 smell, taste, touch, pain, and
...
Basic Principles of
Sensation and
Perception
Your brain will interpret, perceive
these topics as they enter your
sense org...
Sensation vs. Perception
“The process by which our
sensory receptors and
nervous system receive and
represent stimulus ene...
Making sense of the world
What am I
seeing?
Is that
something I’ve
seen before?
Bottom-up
processing:
taking sensory
infor...
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
some...
Top-down
Processing
You may start
to see
something in
this picture if
we give your
brain some
concepts to
apply:
“tree”
“s...
From Sensory Organs to the Brain
The process of sensation can
be seen as three steps:
Reception--
the stimulation
of senso...
Thresholds
The absolute threshold: the
minimum level of stimulus
intensity needed to detect a
stimulus half the time.
Anyt...
When Absolute Thresholds
are not Absolute
10
Signal detection theory
refers to whether or not we
detect a stimulus, especi...
Subliminal Detection
 Although we cannot learn complex
knowledge from subliminal
stimuli, we can be primed, and this
will...
 Difference threshold: the minimum difference (in
color, pitch, weight, temperature, etc) for a person to
be able to dete...
 To help detect novelty in our
surroundings, our senses
tune out a constant stimulus,
such as:
 a rock in your shoe
 th...
Perceptual Set
Perceptual set is what we expect to see, which influences
what we do see.
Perceptual set is an example of t...
Perceptual set can be “primed.”
Old
woman
Young
woman
Ambig
uous
Context Effect on Perception
Spelling test answers:
In which picture does the center dot look larger?
Perception of size d...
Effect of Emotion, Physical State, and
Motivation on Perception
Experiments show that:
 destinations seem farther
when yo...
Vision, and Perceptual Organization
and Interpretation
And: ESP, Perception without Sensation
Vision (Sensation):
 The Ey...
The
Visible
Spectrum
We encounter waves
of electromagnetic
radiation.
Our eyes respond to
some of these waves.
Our brain t...
Color/Hue and
Brightness
We perceive the
wavelength/frequency of
the electromagnetic
waves as color, or hue.
We perceive t...
 Light from the candle passes through the cornea and the
pupil, and gets focused and inverted by the lens. The
light then...
The Retina
The Blind
Spot
 There is an area of missing information
in our field of vision known as the blind
spot. This occurs becau...
Photoreceptors: Rods and Cones
 When light reaches the back of the retina, it triggers
chemical changes in two types of r...
Visual Information Processing
The images we
“see” are not
made of light;
they are made of
neural signals
which can be
prod...
Turning Neural Signals into Images
 In the visual cortex are neurons called feature
detectors: they respond to certain vi...
Parallel Processing
 Turning light into the mental act of seeing:
light waveschemical reactionsneural impulsesfeatures...
Visual Processing
Color Vision
Young-Helmholtz Trichromatic
(Three-Color) Theory
According to this theory, there are
three types of color re...
Color Blindness
People missing red cones or green
cones have trouble differentiating red
from green, and thus have trouble...
Opponent-Process Theory Test
The dot, the dot, keep staring at the dot in the center…
Turning light waves into mental images/movies...
Visual Perceptual Organization
We have perceptual processes for enabling ...
The Role of
Perception
Our senses take in the blue
information on the right.
However, our perceptual
processes turn this i...
Figure-Ground Perception
 In most visual scenes, we pick out objects and figures,
standing out against a background.
 So...
Grouping: How We Make Gestalts
“Gestalt” refers to a meaningful
pattern/configuration, forming a “whole” that is more tha...
Grouping Principles
Which ones influence perception here?
Visual Cliff: A Test of Depth Perception
Babies seem to develop this ability at crawling age.
Even newborn animals fear th...
Perceiving Depth: Binocular Methods
Unlike other animals, humans have
two eyes in the front of our head.
This gives us ret...
Monocular Cue: Interposition
Interposition:
When one object appears
to block the view of
another, we assume that
the block...
Monocular Cue:
Relative Size
We intuitively know to
interpret familiar objects (of
known size) as farther away
when they a...
Monocular Cues:
Linear Perspective and Interposition
The flowers in the
distance seem
farther away
because the rows
conver...
Tricks Using
Linear
Perspective
 These two
red lines
meet the
retina as
being the
same size
 However, our
perception of
...
Monocular Cue: Relative Height
 We tend to perceive
the higher part of a
scene as farther away.
 This scene can look lik...
Monocular Cues: Shading Effects
Shading helps our
perception of
depth.
Does the middle
circle bulge out or
curve inward?
H...
Light and shadow create depth cues.
Monocular Cues: Relative Motion
When we are
moving, we can tell
which objects are
farther away because it
takes longer to ...
Perceptual Constancy
Our ability to see objects as appearing the same
even under different lighting conditions, at
differe...
Color Constancy
 This ability to see a
consistent color in changing
illumination helps us see
the three sides as all bein...
Brightness Constancy
On this screen, squares A
and B are exactly the
same shade of gray.
You can see this when
you connect...
Shape Constancy
Shape constancy refers to the ability to perceive objects
as having a constant shape despite receiving dif...
Size Constancy
 We have an ability to use distance-related context
cues to help us see objects as the same size even if
t...
Visual Interpretation: Restored vision, sensory restriction
Experience shapes our visual perception
 People have grown up...
Perceptual Adaptation
 After our sensory
information is
distorted, such as by a
new pair of glasses or by
delayed audio o...
The Nonvisual Senses
There’s more to Sensation and
Perception than meets the eye
 Hearing: From sound to ear to
perceivin...
Hearing  How do we take a
sensation based on sound
waves and turn it into
perceptions of
music, people, and
actions?
 Ho...
Hearing/Audition: Starting with Sound
Height or
intensity of
sound wave;
perceived as
loud and soft
(volume)
Perceived as
...
Sound Waves Reach The Ear
The outer ear
collects sound
and funnels it
to the eardrum.
In the middle ear, the sound waves h...
The Middle and Inner Ear
Conduction Hearing Loss:
when the middle ear isn’t
conducting sound well to the
cochlea
Sensorine...
Preventing
Hearing Loss
 Exposure to sounds that
are too loud to talk over
can cause damage to
the inner ear, especially
...
Treating Hearing Loss
 People with conduction
hearing loss may be helped
by hearing aids. These aids
amplify sounds strik...
 Loudness refers to
more intense sound
vibrations. This
causes a greater
number of hair cells
to send signals to
the brai...
Sound Perception: Pitch
Frequency theory
At low sound frequencies, hair
cells send signals at whatever
rate the sound is r...
Sound Perception: Localization
How do we seem to know the location of the source
of a sound?
 Sounds usually
reach one of...
Other Senses
We may not have all of the
sensory abilities of the shark
(such as sensing the electric
fields of others) or ...
Touch
Touch is valuable…
 for expressing
and sensing
feelings.
 for sharing
affection, comfort
, and support.
 for dete...
Four Components
of Touch
 Stroking adjacent
pressure spots
creates a tickle.
 Adjacent cold and
pressure sensations
feel...
Pain...what is it good for?
 Pain tells the body
that something has
gone wrong. Pain
often warns of severe
injury, or eve...
Biological Factors in Pain Perception:
The Pain Circuit
Nociceptors are sensory receptors whose
signals are interpreted by...
 Gate-Control Theory
This theory hypothesizes that the spinal cord contains a
neurological “gate” that blocks pain signal...
Psychological Influences on Pain
Distraction, such as
during intense
athletic competition,
can limit the
experience of pai...
Social and Cultural Influences
on Pain Perception
 Social contagion
We feel more pain if other people are experiencing
pa...
Controlling/Managing/Reducing Pain
 Pain can be reduced through drugs, acupuncture, electrical
stimulation, exercise, hyp...
Biopsychosocial Influences on
Pain Perception
Examples of each
influence:
 gate control
 selective
attention
 empathy p...
Sweet:
energy source
Sour:
potentially toxic
acid
Umami:
(savoriness)
proteins to grow
and repair
tissue
Salty: sodium
ess...
Neurochemistry of Taste
 There are no regions of the tongue,
just different types of taste
receptor cells projecting hair...
Smell: Odor Receptors
Humans have a poor sense of smell for an animal. Even
so, humans have 350 different types of smell r...
Smell: The Shortcut Sense
 Sensations of smell take a
shortcut to the
brain, skipping the trip
through the “sensory
switc...
Sensing Body Position and Movement
 Kinesthesis (“movement
feeling”): sensing the
movement and position of
individual bod...
Sensing Body Position and Movement
 Vestibular sense: the ability to sense
the position of the head and body
relative to ...
Mixing the different senses together
Sensory interaction occurs
when different senses
influence each other.
For example:
...
Embodied Cognition
 holding a warm mug promotes social warmth.
 social rejection looks like pain reception in the brain....
Extrasensory Perception (ESP)
Extrasensory Perception (ESP) can defined, literally, as
perception without sensation.
Belie...
Summarizing the Senses
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PSY 150 403 CHAPTER 6 SLIDES

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  • Click to reveal all bullets.
  • No animation.
  • 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…
  • Click to reveal bullets and two examples.
  • 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.
  • Click to reveal second text box.
  • No animation.
  • No animation.
  • 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.
  • Click to show bullets and example.
  • Click to invert the image and show the hollow as a hill.
  • No animation.
  • 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.”
  • Click to reveal bullets and animate example.
  • 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.
  • Click to reveal bullets and to show explanation.
  • Click to reveal bullets.
  • Click to reveal bullets.
  • No animation.
  • Click to reveal bullets.
  • 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.
  • No animation.
  • Click to reveal bullets.
  • Click to reveal bullets.
  • Click to reveal bullets.
  • Click to reveal three text boxes.
  • 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.
  • Click to reveal bullets.
  • Click to reveal bullets.
  • Click to reveal bullets.
  • 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.
  • No animation.
  • 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.
  • Click to reveal bullets.
  • Click to reveal bullets.
  • 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.
  • Click to reveal bullets.
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  • Click to reveal bullets and definition.
  • 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.
  • No animation.
  • Transcript of "PSY 150 403 CHAPTER 6 SLIDES"

    1. 1. Sensation and Perception PowerPoint® Presentation by Jim Foley Chapter 6
    2. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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?
    15. 15. Perceptual set can be “primed.” Old woman Young woman Ambig uous
    16. 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. 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. 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. 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. 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. 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
    22. 22. The Retina
    23. 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. 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. 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. 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. 27. Parallel Processing  Turning light into the mental act of seeing: light waveschemical reactionsneural impulsesfeaturesobjects 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:
    28. 28. Visual Processing
    29. 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. 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.
    31. 31. Opponent-Process Theory Test The dot, the dot, keep staring at the dot in the center…
    32. 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. 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. 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. 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.
    36. 36. Grouping Principles Which ones influence perception here?
    37. 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. 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
    39. 39. Monocular Cue: Interposition Interposition: When one object appears to block the view of another, we assume that the blocking object is in a position between our eyes and the blocked object.
    40. 40. Monocular Cue: Relative Size We intuitively know to interpret familiar objects (of known size) as farther away when they appear smaller.
    41. 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. 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. 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. 44. Monocular Cues: Shading Effects Shading helps our perception of depth. Does the middle circle bulge out or curve inward? How about now?
    45. 45. Light and shadow create depth cues.
    46. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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.
    73. 73. Biopsychosocial Influences on Pain Perception Examples of each influence:  gate control  selective attention  empathy pain
    74. 74. Sweet: energy source Sour: potentially toxic acid Umami: (savoriness) proteins to grow and repair tissue Salty: sodium essential to physiological processes Bitter: potential poisons Taste Our tongues have receptors for five different types of tastes, each of which may have had survival functions.
    75. 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. 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. 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. 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. 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. 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. 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. 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.
    83. 83. Summarizing the Senses
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