Unit 3:
Sensation and Perception
MrGalusha.org
3.1 Principles of Sensation
Sensation (Bottom-up processing)
Perception (Top-down processing)
Transduction
Absolute Threshold
Signal Detection Theory
Sensory Adaptation
Difference Threshold
Weber’s Law
What do you see vs. What do you perceive?
What do you see vs. what do you perceive?
What do you see vs. what do you perceive?
What do you see vs. what do you perceive?
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External Stimuli
Something from the world outside of your brain/nervous system.
In sensation, stimuli comes in the form of physical energy
What are sensation and perception?
sensation
The process by which
our sensory receptors and nervous system receive and represent
stimulus energies from our environment.
perception
The process of
organizing and interpreting
sensory information, enabling us
to recognize meaningful objects and events.
So what does that actually mean?
sensation
Your nose, eyes or other sensory organs bring in information…. a smell… a color… a tall, blond boy with freckles…
perception
Your brain makes sense of that information… oh.. that is my granddad’s rhubarb pie, that turquoise shirt is stunning, hey… is that my brother?
Does this image represent sensation or perception?
How do you know?
For each of the senses below, provide an example of how sensing differs from perceiving.
vision
audition (hearing)
gustation (tasting)
touch, temperature and pain
How does processing of stimuli work?
bottom-up processing
Starting with the sensory input, the brain attempts to understand/make sense.
You see a long, slim, slithering creature on the ground… you process… ah! A snake!
top-down processing
Guided by experience and higher-level processes, we see what we expect to see.
An experienced hiker, you expect to see snakes on your hike so windy stick, lizards, etc. all seem like snakes.
In the image below, what can we detect through bottom-up processing? Top down processing?
Did you see it?
Our sensory and perceptual processes work together to help us sort out complex images, including the hidden couple in Sandro Del-Prete’s drawing,
The Flowering of Love.
What are the three steps involved in �sensation and what is transduction?
Transduction:
conversion of one form of energy, such as light waves, into another form, like neural impulses that our brain can interpret
STEP ONE
receive
STEP TWO
transform
STEP THREE
deliver
What is the difference between �absolute threshold and difference threshold?
absolute threshold
The minimum stimulation
needed to detect a particular stimulus 50 percent of the time.
difference threshold
The minimum difference between two stimuli required for detection 50 percent of the time.
This is termed the just noticeable difference or JND.
How do we test for absolute threshold in a sense like audition?
A hearing specialist exposes both of your ears to varying sound levels.
For each tone the test defines the pitch at which you can detect the tone 50% of the time.
So you can see the light…but how can you tell when it gets brighter?
Have you ever been in a crowd of families, like at a waterpark or amusement park, and you yell “Dad!” to get your father’s attention? How does YOUR Dad know to turn around?
How does a musician know when they are playing a little flat or sharp of their intended note?
How can you tell when just the slightest note of irritation is in your friend’s voice?
What is Weber’s Law?
To be able to tell the difference between degrees of stimulation, two stimuli must differ by a constant minimum percentage.
How will I notice the difference?
How does Weber’s Law help explain the �just noticeable difference (jnd) ?
The difference threshold is the minimum difference between two stimuli required for detection
50 percent of the time.
We experience the difference threshold as a just noticeable difference (or jnd).
Weber’s law tells us that the difference must vary by a constant percentage (as shown on the last slide), not a constant amount.
Why are some people better at detecting signals than others?
A theory predicting how and when we detect the presence of a faint stimulus amid background stimulation
What is the signal detection theory?
the strength of the signal
(how loud the sound is, how bright the light, how heavy the touch….)
our psychological state
(our experience, our expectations, our motivation, and how alert we are)
Depends on two conditions:
How many lines are required for you to experience a just noticeable difference (jnd)?
What are subliminal stimuli and �how are we affected by them?
Subliminal stimuli are not detectable 50% of the time. They are below your absolute threshold.
You may not notice subliminal stimuli at all if they are weak.
What is sensory adaptation?
Sensory adaptation is diminished sensitivity to stimuli as a consequence of constant stimulation.
Evolutionary psychologists suggest that once we notice and evaluate a new stimuli as non-threatening, we can pay less attention to it.
This saves our attention for new incoming stimuli, or changes in the existing stimuli. This could be adaptive for survival.
Stop and talk. Has this happened to you?
Ever notice how your friend’s home has a certain….smell? And have you noticed that it “goes away” after you have been there a few minutes? Why?
Do you ever look all around for your cell phone only to realize it is in your pocket?
Has a family member fallen asleep in front of the TV and to be kind, you turn off the TV and cover them with a blanket? Do they wake up? Why?
So why does sensory adaptation occur?
3.2 Principles of Perception
Selective Attention
Inattention Blindness
Change Blindness
Subliminal
Perceptual Set
What is selective attention?
The first step in Perception is Attention
Has this happened to you?
YOUR name…and you HEAR it!!
Do you text or talk on your cell phone while driving your car?
Selective attention and accidents
Let’s consider the research on selective attention…
fMRI scans show a 37% decrease in brain activity in areas vital to driving when a driver is listening to a conversation. (Just et al., 2008)
University of Sydney researchers found that cell phone users were four times more at risk of a car crash.
(McEvoy et al., 2005, 2007)
The National Safety Council found that 28% of traffic accidents occur when drivers are chatting on cell phones or texting. (NSC, 2010)
It is not about the cell phone.. it’s about distracting your attention!
Using a cell phone (even a hands-free set)
carries a risk 4 times higher than normal—
equal to the risk of drunk driving
(McEvoy et al., 2005, 2007).
Inattentional blindness: ��failing to see visible objects when our attention or focus is directed elsewhere
Viewers of this basketball drill are asked to count the number of passes between white-shirted players.
An umbrella toting woman saunters across the screen.
Only 21% reported the presence of the woman.
(Neisser, 1979)
Change blindness:��failing to notice changes in the visual environment
While a white-haired man provides directions to a construction worker…
two researchers rudely pass between
them interrupting his vision…
the original worker switches places with another person. 67% failed to notice the change.
Subliminal
Subliminal Messages?
…You Decide
Could 1/30th of a second really influence impressions of Al Gore?
Types of Subliminal Messages?
Vicary’s Study
Except . . . .
Maybe Backmasking works?
Not the last of it…
Why? Perceptual Set!!!
This is not to say that sex isn’t used in ads.
Product Placement = Not subliminal!
Product Placement
Product Placement
We are not obedient to Subliminal Messages
Perceptual Set Activity
Group A
Group B
In the picture was there . .
Conclusion
Priming
Extrasensory Perception
Ganzfeld Procedure
scientific support
3.3 Visual Anatomy-
Cornea
Pupil
Iris
Lens
Retina
Fovea
Rods
Cones
Optic Nerve
Blind Spot
Feature detectors
Young-Helmholtz Trichromatic Theory
Color Blindness
Opponent-process Theory
Afterimage effect
Can People In Libraries Read
1
2
3
4
5
What is the cornea?
The cornea is the eye’s clear, protective outer layer covering the pupil and iris.
Light enters the eye first through the cornea.
What is the pupil?
The pupil is a small adjustable opening in the center of the eye through which light passes.
What is the iris?
The iris is a ring of muscle tissue that
forms the colored portion of the
eye around the pupil and controls
the size of the pupil opening by expanding and contracting over the pupil.
What is the lens?
The lens is the transparent structure
behind the pupil that changes shape
to help focus images on the retina.
How does the lens change shape?
To focus the rays, the lens changes its curvature and thickness in a process called accommodation.
If the lens focuses the image on a point in front of the
retina, you see near objects clearly but not distant objects. This nearsightedness—myopia—
can be remedied with glasses, contact lenses, or surgery.
Hyperopia- farsightedness – is a result of the lens focusing light past the retina.
What is the retina?
The retina is the light-sensitive inner
surface of the eye, containing
the receptor rods and cones plus
layers of neurons that begin the
processing of visual information.
Where is the retina located?
The retina is along the back of the eye and contains the sense receptor cells (rods and cones) that will receive the incoming light waves.
What is the fovea?
The fovea is the central focal point in
the retina, around which the eye’s
cones cluster.
This is the area of greatest visual acuity… or sharpness of focus.
What happens in the retina?
Light waves are transduced into neural impulses by the rods and cones, then passed to the bipolar cells and the ganglion cells.
What are rods?
The rods are retinal photoreceptors that detect black, white, and gray, and are sensitive to movement.
Rods are necessary
for peripheral and twilight vision, when cones don’t respond.
What are some characteristics of rods?
Rods are located along the retina’s outer periphery.
Rods remain sensitive in dim light, and they enable
black-and-white vision.
Rods have no hotline to the brain…they share connections to a single bipolar cell sending a combined message to the brain.
Rods are sensitive to faint light and peripheral motion.
What are cones?
Cones are retinal photoreceptors that are
concentrated near the center of the retina and function in daylight or in well-lit conditions.
Cones detect fine detail and create color sensations.
What are some characteristics of cones?
Cones cluster in and around the fovea.
In dim light, cones become unresponsive and we are unable to see color.
Many cones have their own hotline to the brain: One
cone transmits its message to a single bipolar cell, which relays the message to the visual cortex (where a large area receives input from the fovea).
How many dots do you see at once?
Look at or near any of the twelve black dots and you can see them, but not in your peripheral vision.
What is the �optic nerve?
The optic nerve is comprised of the axons of the ganglion cells.
It leaves through the back of the eye and carries the neural impulses from the eye to the brain.
What is the �blind spot?
The optic disk is the point at which the
optic nerve leaves the eye, creating
a “blind” spot because no receptor
cells (rods or cones) are located there.
Can you find the blind spot of your eye?
Close your left eye, look at the spot, and move your face away until one of the cars disappears. Repeat with your right eye closed. Did the other car disappear? Can you explain why?
What happens to the neural impulse after it exits the eye?
The optic nerve carries the impulse to the thalamus and on to the visual cortex of the occipital lobes.
What are feature detectors and �where are they located?
Feature detectors are nerve cells located in the visual cortex of the occipital lobe that respond to a scene’s edges, lines, angles and movements.
But what do feature detectors do?
Feature detectors receive information from individual ganglion cells in the retina and
pass it to other cortical areas, where
supercell clusters respond to more complex patterns.
Color Vision:
2 theories at work
Rods and Cones
Trichromatic Color Theory
Color blindness
Color Blindness
Dichromatic Problems with reds and greens
Dichromatic Problems with Blues and Greens
Color Blindness Tests
What about people who cannot see color?
The photo on the left shows how people with red-green deficiency perceived a 2015 Buffalo Bills versus
New York Jets football game.
“Everyone looks like they’re on the same team,”
said one color-blind fan.
The photo on the right shows how the game looked
for those with normal color vision.
What are some characteristics of �color blindness?
About one person in 50 is color blind.
Males are more affected since the defect is
genetically sex-linked.
Most people are not actually blind to all colors. They simply lack functioning red- or green-sensitive cones, or sometimes both.
Vision is monochromatic (one color) or dichromatic
(two-color) and seems ‘normal’ to them.
How does color blindness prove Trichromatic Theory
AP® Exam Tip 2
There is typically a question about color blindness on
the AP ® Exam.
It is important to remember that color blindness is most prevalent in males and that the red-green cone deficiency is the most common form of color blindness.
Mantis Shrimp
12 different cones!
Mantis Shrimp
Mantis Shrimp Debunked!
Opponent Process Theory
Opponent Process theory helps us explain the after-image effect
How does after image prove Opponent Process?
Neuroscience of ghosts!
Alas poor Yorick it was an after-image!
So… how does color processing occur?
1
The retina’s red, green, and blue cones respond in varying degrees to different color
stimuli, as the Young-Helmholtz trichromatic theory suggested.
2
The cones responses are then processed by opponent-process cells, as Hering’s
opponent-process theory proposed.
3.4 Visual Perception
Gestalt
Figure Ground
Depth Perception
Visual Cliff
Binocular Cues
Retinal Disparity
Convergence
Monocular Cues
Phi Phenomenon
Perceptual Constancy
Color Constancy
Our brains are meaning machines
Gestalt Psychology
How did the Gestalt psychologists �understand perceptual organization?
Early in the twentieth century, a group of German psychologists noticed that people who are given a cluster of sensations tend to organize them into a gestalt, a German word meaning a “form” or a “whole.”
Gestalt psychologists believe that in perception,
the whole may exceed the sum of its parts.
How is perception understood �by the Gestaltists?
Underlying Gestalt principles is a fundamental truth:
Our brain does more than register information
about the world.
Perception is not just opening a shutter and letting a picture print itself on the brain. We filter incoming
information and construct perceptions. Mind matters.
How does the Necker cube illustrate a Gestalt?
The individual elements of this figure, called a Necker cube, are really nothing but eight blue circles, each containing three converging white lines.
When we view these elements all together, however, we see a cube that sometimes reverses direction.
AP® Exam Tip 1
The Necker cube is an excellent vehicle for understanding the distinction between sensation and perception.
The only visual stimuli are the blue wedges. (sensation)
The circles, lines, and cube are all the products of your mind and not on the page. (perception)
What is figure-ground?
the organization
of the visual field into objects (the figures) that stand out from their
surroundings
(the ground)
How do the Gestaltists apply rules for grouping to perception?
Our mind brings order and form to stimuli by following certain rules for grouping, also identified by the Gestalt psychologists.
These rules, which we apply even as infants and
even in our touch perceptions, illustrate how the perceived whole differs from the sum of
its parts, rather as water differs from its hydrogen and oxygen parts.
First step in visual PERCEPTION
Examples of figure-ground
What you make the figure and what you back the background determines your perception
Examples of figure-ground
Figure-ground
Figure-ground examples
We organize by closure
Closure
What is closure?
A Gestalt law of grouping that states we fill in gaps to create a complete, whole object. Thus we assume that the
circles on the left are complete but partially blocked by the (illusory) triangle. Add nothing more than little line segments to close off the circles and your brain stops
constructing a triangle.
Continuity
What is continuity?
A Gestalt law of grouping that states we perceive smooth, continuous patterns rather than discontinuous ones.
This pattern could be a series of alternating semicircles, but we perceive it as two continuous lines—one wavy, one straight.
We organize by Proximity
Proximity
What is proximity?
A Gestalt law of grouping that states we group nearby figures together.
We see not six separate lines, but three sets
of two lines.
Proximity and Closure
We organize by Similarity
Similarity
We organize by similarity
They are predictable and therefore they can be exploited.
What is depth perception and how have we tested for it?
Depth perception is the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance.
Eleanor Gibson and Richard Walk (1960) designed a series of experiments in their Cornell University laboratory using a visual cliff—a model of a cliff with
a “drop-off” area that was actually
covered by sturdy glass.
What did the visual cliff demonstrate?
6- to 14-month-old infants were placed on the edge of the “cliff” and coaxed by their mothers to crawl out onto the glass.
Most infants refused to do so, indicating that they could perceive depth.
What are binocular cues and how do �they help us judge depth?
Binocular cues are depth cues, such
as retinal disparity and convergence, that depend
on the use of two eyes.
As an object becomes closer or father, both binocular depth cues operate to help us judge distance.
What is convergence?
To focus on close objects, the eyes must point inward. Muscles monitor the angle. The greater the angle and the great the tension in those muscles, the closer the object.
convergence
Hold your textbook or other written material out at arm’s length and focus on the words on the page. While maintaining your focus (you may have to blink!), slowly bring the book closer and closer to your eyes.
Do you feel the slight pain/tightening around your eyes?
As the four muscles surrounding the eye work to move the eye to focus, they send signals to the brain that the object in front of you is getting closer.
How does retinal disparity work?
By comparing retinal images from the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.
What are monocular cues and how do �they help us judge depth?
How do we judge whether a person is
10 or 100 meters away?
Retinal disparity won’t help us here, because there won’t be much difference between the images cast on our right and left retinas.
At such distances, we depend on monocular cues (depth cues available to each eye separately).
What is relative size?
If we assume two objects are
similar in size, most people perceive the one
that casts the smaller retinal image as farther
away.
What is interposition?
If one object partially blocks
our view of another, we perceive it as closer.
The deer block the tree trunk…so the tree trunk seems farther.
Monocular Cues
Relative Clarity: Because light from distant objects passes through more light than closer objects, we perceive hazy objects to be farther away than those objects that appear sharp and clear.
What is relative motion?
As we move, objects
that are actually stable may appear to move. If while riding on a bus you fix your gaze on some point—say, a house—the objects beyond the fixation point will appear to move with you.
Objects in front of the point will appear to move backward.
The farther an object is from the fixation point, the faster it will seem to move.
What is linear perspective?
Parallel lines appear to meet in
the distance.
The sharper the angle of convergence,
the greater the perceived distance.
How does the brain perceive depth using linear perspective cues?
The yellow sign and the car, which are farther away from where the two parallel lines of the road seem to come together are perceived as close.
The car in this image is closer to where the two parallel lines seem to come together and is perceived as farther away.
AP® Exam Tip 2
The illustrations in the previous slides provide you with excellent opportunities to practice identifying
monocular depth cues.
To really demonstrate your understanding,
look for these cues in other drawings, photographs and real life.
There are almost always cues to identify and often more than one monocular cue will be present in an image.
This practice will help you master the terms for the
AP® exam.
What is stroboscopic movement and �the phi phenomenon?
Our brain perceives a rapid series of slightly varying images as continuous movement (a phenomenon called stroboscopic movement).
We construct that motion in our heads, just as we construct movement in blinking marquees and holiday lights.
We perceive two adjacent stationary lights blinking on and off in quick succession as one single light moving back and forth. Lighted signs exploit this phi phenomenon with a succession of lights that creates the impression of, say, a moving arrow.
What is a perceptual constancy?
Perceptual constancy is a top-down process that recognizes objects without being deceived by changes in their color, brightness, shape, or size.
Regardless of the viewing angle, distance, and illumination, we can identify people and
objects quite quickly.
Even if the image on our retina seems changing, our brain can keep it constant.
What is brightness constancy?
We
perceive an object as having a constant brightness even as its illumination varies. This perception
of constancy depends on relative luminance—the amount of light an object reflects
relative to its surroundings.
What is color constancy?
perceiving
familiar objects as having consistent color, even if changing
illumination alters the wavelengths
reflected by the object
What is shape constancy?
We perceive an object as having an unchanging shape, even while
our distance from it varies.
What is size constancy?
We perceive an object as having an unchanging size
even while our distance from it varies.
We assume a car is large enough to carry people, even when we see its tiny image from two blocks away.
So…to our eyes…it appears an object
(a car, a friend…) moving away from us
is getting smaller.(sensation)
But our brain understands that friends and cars don’t shrink like that and interprets the visual input as an increase in distance. (perception)
3.5 Auditory Sensation and Perception-
Frequency
Pitch
Middle Ear
Cochlea
Inner Ear
Place Theory
Frequency Theory (Volley Principle)
Sensorineural Hearing Loss
Conduction Hearing Loss
Cochlear Implant
What are characteristics of �sound waves?
frequency (wavelength)
amplitude (height)
Pitch -
How do air pressure waves �become sound?
Draw a bow across a violin, and you will unleash the energy of sound waves.
Air molecules, each bumping into the next, create waves of compressed and expanded air, like the ripples on a pond circling out from a tossed stone.
As we swim in our ocean of moving air molecules,
our ears detect these brief air pressure changes.
What information do sound waves �give us?
What pitch am I hearing?
How loud is the sound I am hearing?
Would you expect long or short �wavelengths…
1
…when a soprano sings an aria?
2
…when a baritone sings along?
AP® Exam Tip 1
Note that both light and sound travel in waves.
In each case, the amplitude and length of the waves
are important to learn for the AP® exam.
What is audition?
the sense or act of hearing
What are the three divisions of the ear?
The ear is divided into outer, middle and inner sections.
How does the ear transform sound �into neural messages?
Passing through accessory structures to sense receptors, vibrating air triggers nerve impulses that the
brain decodes as sounds.
What is the auditory canal?
the channel located in the outer ear that funnels sound waves from the pinna to the tympanic membrane
(ear drum)
What is the ear drum (tympanic membrane)?
The ear drum, or the tympanic membrane, is a thin layer of tissue that vibrates in response to sound waves.
What are the ossicles?
The ossicles, made up of the three smallest bones in the human body, the incus, the malleus and the stapes, transfer the sound wave vibrations from the tympanic membrane to the oval window of the cochlea.
What is the oval window?
The oval window is the membrane-covered opening of the cochlea. It vibrates when it receives the sound waves and causes the fluid inside the cochlea to move.
What is the cochlea?
The cochlea is a coiled, bony, fluid-filled tube in the inner ear.
Sound waves traveling through the cochlear
fluid trigger
nerve impulses.
Can you trace the path of sound �through the ear so far?
Use the terms you just learned to label each structure.
How does the sound wave move �through the inner ear?
Accessory structures move the sound wave to the sense receptors(stereocilia) in the inner ear where the wave energy undergoes transduction to neural energy that the brain can interpret.
How does transduction �occur in the inner ear?
The motion of the sound vibration against the oval window of the cochlea causes ripples in the basilar membrane,
bending the hair cells lining its surface,
AP® Exam Tip 3
Although the basilar membrane is not considered a key term in your text, it is considered a key term on the AP® exam.
Free-Response Questions (FRQs) and multiple choice questions frequently ask about the basilar membrane.
Make sure to learn about the way sound waves are transduced into neural impulses via the cilia on the basilar membrane.
How does the nerve impulse �move out of the ear?
The hair cell (cilia) movements in turn trigger impulses in adjacent nerve cells, whose axons
converge to form the auditory nerve.
How does the message carry to the brain?
The auditory nerve carries the neural messages to your
thalamus and then on to the auditory cortex in
your brain’s temporal lobes.
Trace the path of sound through the ear.
Put it all together and label the process.
How does the brain detect loudness?
A soft, tone activates only the few hair cells attuned to its frequency.
Given louder sounds, neighboring hair cells also respond.
Thus, the brain interprets loudness from the number of activated hair cells.
What is one theory of how the �brain detects pitch?
What is the frequency theory?
How does the volley principle explain �hearing higher frequency sounds?
can alternate firing.
How do the two theories work together to explain how we hear pitch?
Place theory best explains how we sense
high pitches.
Frequency theory, extended by the volley principle, also explains how we sense low pitches.
Finally, some combination of place
and frequency theories likely explains how we sense pitches in the intermediate range.
How do we locate sounds?
Sound waves strike one ear sooner and more intensely than
the other. From this information, our nimble brain can compute the sound’s location.
What are two types of hearing loss?
sensorineural
Damage to the cochlea’s hair cell receptors or the auditory nerve can cause
sensorineural hearing loss.
With auditory nerve damage, people
may hear sound but have trouble discerning what someone is saying.
conduction
Damage to the mechanical system—the eardrum and middle ear bones—that conducts sound waves to the cochlea can cause conduction hearing loss. It is less common than sensorineural hearing loss.
How much sound is too much sound?
As a general rule, any noise we cannot talk over (loud machinery, fans screaming
at a sports event, music blasting at maximum volume) may be harmful, especially if prolonged
and repeated.
(Roesser, 1998)
What is the problem with headphones?
Headphones direct all of the sound waves into the auditory canal and bombard the basilar membrane.
In the open air, sound waves disperse and are not all directed to one location.
What is a cochlear implant?
a device for
converting sounds into electrical
signals and stimulating the
auditory nerve through electrodes
threaded into the cochlea
How does a cochlear implant work?
Cochlear implants work by translating sounds into electrical signals that are
transmitted to the cochlea and, via the auditory nerve, relayed to the brain.
3.6 Chemical Senses
Gustation (taste)
Olfaction (smell)
What are the two chemical senses?
taste (gustation)
On the top and sides of your tongue are 200 or more taste buds, each containing a pore that catches food chemicals.
Smell (olfaction)
We smell something when molecules of a substance
carried in the air reach a tiny cluster of receptor cells at the top of each nasal cavity.
What are the five basic tastes we can detect?
Tastes exist for more than our pleasure.
What food can you think of that is….
sweet
salty
bitter
sour
umami
How do we actually taste food?
In each taste bud pore, 50 to 100 taste receptor cells project antenna-like hairs that sense food molecules. This is where the chemicals in food are transduced to neural messages for the brain.
Some receptors respond mostly to sweet-tasting molecules, others to salty-, sour-, umami-, or bitter-tasting ones.
Each receptor transmits its message to a matching partner cell in your brain’s temporal lobes.
How does our sense of smell operate?
These 20 million olfactory receptors
respond selectively—to the aroma of a cake baking, to a wisp of smoke, to a friend’s fragrance.
This is where odors are transduced to neural messages for the brain.
Instantly, they alert the brain through their axon fibers.
The process of olfaction (smell)
What happens next?
Sniffing swirls air up to the receptors, enhancing the aroma.
The receptor cells send messages to the brain’s olfactory bulb, and then onward to the temporal lobe’s primary smell cortex and to the parts of the limbic system involved in memory and emotion.
AP® Exam Tip
The sense of smell (olfaction) is the only one of the five senses that does not pass neural information through the thalamus.
This is often a question on the AP® exam.
How are taste, smell and memory related?
Information from the taste buds (yellow arrow) travels to an area between the frontal and temporal lobes of the brain.
This information registers near where the brain receives input from our sense of smell, which interacts with taste. 90% of our experience of food is from smell!
In what other way are taste, smell and �memory related?
The brain’s circuitry for smell (red area) also connects with areas involved in memory storage, which helps explain why a smell can trigger a memory.
Let’s look at the research on the relationship…
When put in a foul-smelling room, people expressed harsher judgments of other people and of immoral acts.
(Inbar et al., 2011; Schnall et al., 2008)
Exposed to a fishy smell, people became more suspicious.
(Lee et al., 2015).
And when riding on a train car with the citrus scent of a cleaning product, people have left behind less trash.
(de Lange et al., 2012)
3.7 Body Senses
Kinesthetic Sense
Vestibular Sense
Biopsychosocial View of Pain
Gate Control Theory
Synesthesia
How do we sense our body’s �position and movement?
vestibular sense
Fluid-filled semicircular canals and a pair of calcium crystal-filled vestibular sacs located in the ears monitors the body’s overall position.
How do we sense our body’s �position and movement?
kinesthetic sense
Position and motion detectors in muscles, tendons and joints sense the position and movement of body parts.
How do we sense touch?
Our “sense of
touch” is a mix of four basic and distinct skin senses, pressure, warmth, cold, and pain.
How does the somatosensory cortex help us sense touch?
We discussed the somatosensory cortex in Module 12. This section of the brain receives incoming sensory information from our skin, as well as other senses.
How is pain best understood?
Our experience of pain reflects both bottom-up sensations and top-down cognition.
Pain is a biopsychosocial event.
As such, pain experiences vary widely, from
group to group and from person to person.
How is pain a biopsychosocial event?
How is pain biological?
Sensory receptors called nociceptors—mostly in your skin, but also in your muscles
and organs—detect hurtful temperatures,
pressure, or chemicals.
What is a pain circuit?
Sensory receptors (nociceptors)
respond to potentially damaging stimuli by sending an impulse to
the spinal cord, which passes the message to the brain, which
interprets the signal as pain.
What is the gate-control theory?
The gate-control theory states that the spinal cord contains a neurological “gate” that blocks
pain signals or allows them to pass on to the brain.
The “gate” is opened by the activity of pain
signals traveling up small nerve fibers and is closed by activity in larger fibers (such as massage) or
by information coming from the brain
(such as distracting thoughts).
What is phantom-limb pain?
The brain can create pain, as it does in phantom limb sensations after a limb amputation.
Without normal sensory input, the brain may misinterpret and amplify spontaneous but irrelevant
central nervous system activity.
7 in 10 such people feel pain or movement in nonexistent limbs.
(Melzack, 1992, 2005)
How is pain psychological?
Pain is impacted by how much attention we give to it. If we distract our minds with other thoughts, the pain feels as if it has diminished.
How else is pain psychological?
Our memories of pain may be edited from the actual pain we felt.
People overlook a pain’s duration and recall two moments: pain’s peak moment and how much pain is
felt at the end.
How is pain social-cultural?
We tend to perceive more pain when others seem to be
experiencing pain.
How else is pain social-cultural?
We get cues on how to perceive pain from our culture’s views on pain.
Think of a recent pain event in your life…
…what were the biological causes?
…what were the psychological causes?
… what were the social-cultural causes?
What are some methods for controlling pain?
Pain control therapies may include drugs, surgery,
acupuncture, electrical stimulation, massage, exercise, hypnosis, relaxation training, meditation, and thought distraction.
How might placebos reduce pain?
In an experiment, researchers pitted two placebos—fake pills and pretend acupuncture—
against each other.
People with persistent arm pain received either fake acupuncture (with trick needles that
retracted without puncturing the skin)
or
blue cornstarch pills that looked like a medication often prescribed for strain injury.
What were the results?
After two months, both groups were reporting less pain, with the fake acupuncture group reporting the greater pain drop.
A quarter of those receiving the nonexistent needle pricks and 31 percent of those receiving the fake pills even complained of side effects, such as painful
skin or dry mouth and fatigue.
(Kaptchuk et al., 2006)
How might distraction reduce pain?
For burn victims undergoing painful skin repair, an escape
into virtual reality can powerfully distract attention, thus reducing pain and the brain’s response to painful stimulation.
What is synesthesia?
In a few select individuals, the brain circuits for two or more senses become joined in a phenomenon called synesthesia, where the stimulation of one sense (such as hearing sound)
triggers an experience of another
(such as seeing color).
Synesthetes may hear music as colors or
experience numbers as tastes.