UNIT 3: Sensation and Perception
Learning Targets
25-1 Describe the sense of touch.
25-2 Discuss the biological, psychological, and social-cultural influences that affect our experience of pain and explain how placebos and distraction help control pain.
25-3 Compare and contrast our senses of taste and smell.
25-4 Explain how we sense our body’s position and movement.
25-5 Discuss how sensory interaction influences our perceptions, and explain the concept of embodied cognition.
How do we sense touch?
Our “sense of
touch” is a mix of four basic and distinct skin senses, pressure, warmth, cold, and pain and our other skin
sensations are variations of 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 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.
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)
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.
vestibular sense
Fluid-filled semicircular canals and a pair of calcium crystal-filled vestibular sacs located in the ears monitors the head’s (and body’s) movements.
1. What Would You Answer?
Which of the following is the best example of your kinesthetic sense?
B. Maintaining balance in your chair.
C. Detecting both sweet and sour in a beverage.
D. Smelling the soup your dad is cooking for dinner.
How do our senses interact?
Our senses can influence each other.
we close our nose.
with a visual cue.
What is an example of sensory interaction?
We can hear soft sounds better when they are paired with a visual cue.
Seeing the speaker forming the words, which Apple’s FaceTime video-chat feature allows, makes those words easier to understand
for hard-of-hearing listeners.
(Knight, 2004)
What is embodied cognition?
the influence of bodily sensations,
gestures, and other states on
cognitive preferences and judgments
What does research show about �embodied cognition?
After holding a warm drink rather than a cold one, people were more likely to rate someone more warmly, feel closer to them, and behave more generously.
(IJzerman & Semin, 2009; Williams & Bargh, 2008).
After being given the cold shoulder by others, people
judged the room to be colder than did those who had been treated warmly.
(Zhong & Leonardelli, 2008).
Sitting at a wobbly desk and chair makes others’ relationships, or even one’s own romantic relationship, seem less stable.
(Forest et al., 2015; Kille et al., 2013).
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.
2. What Would You Answer?
Ester is walking to class when she notices someone
in the distance suddenly duck into a dark doorway.
As she chases the figure, she misjudges the distance
and runs into the door and falls down. She laughs
when she discovers that the mystery person is her
roommate, who was avoiding Ester, because she
had borrowed Ester’s favorite sweater without permission and was afraid Ester might be angry.
Question on next page…
2. What Would You Answer? cont.
Use the following terms to explain the perceptual
processes involved in Ester’s scenario:
Learning Target 25-1 Review
Describe the sense of touch.
Our sense of touch is actually several senses—pressure, warmth, cold, and pain—that combine to produce other sensations, such as hot.
Learning Target 25-2 Review
Discuss the biological, psychological,
and social-cultural influences that
affect our experience of pain.
Learning Target 25-2 Review cont.
Discuss the biological, psychological,
and social-cultural influences that
affect our experience of pain.
Learning Target 25-2 Review, part III
Explain how placebos and distraction
help control pain.
Learning Target 25-3 Review
Compare and contrast our senses of
taste and smell.
Learning Target 25-4 Review
Explain how we sense our body’s
position and movement.
Learning Target 25-5 Review
Discuss how sensory interaction
influences our perceptions.
Learning Target 25-5 Review cont.
Explain the concept of
embodied cognition.
The brain circuits that process physical sensations may interact with brain circuits responsible for cognition, leading to embodied cognition: the influence of our body sensations on our cognitive preferences and judgments.