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12
MODULE
The Other Senses
MODULE PREVIEW
Although vision is probably our most important sense, the other senses are vital to our ability to
function. In hearing, sound waves are transmitted to the fluid-filled cochlea, where they are converted to neural messages and sent to the brain. We locate sounds by differences in the timing and
loudness of the sounds received by each ear. The sense of touch is actually four senses—pressure,
warmth, cold, and pain—that combine to produce other sensations such as “hot.” Taste, a chemical
sense, is a composite of sweet, sour, salty, bitter, and umami sensations and of the aromas that
interact with information from the taste buds. Smell, also a chemical sense, does not have basic
sensations as there are for touch and taste. Our effective functioning also requires a kinesthetic
sense and a vestibular sense, which together enable us to detect body position and movement.
MODULE GUIDE
Hearing
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Exercise: Auditory Demonstrations on CD
Lectures: Synesthesia; Recognizing Our Own Voice
PsychSim 5: The Auditory System
Transparencies: 64 The Intensity of Some Common Sounds; 65 Hear There: How We Transform Sound Waves Into
Nerve Impulses That Our Brain Interprets
1. Describe the auditory process, including the stimulus input and the structure and function of the
ear.
Audition, or hearing, is highly adaptive. The pressure waves we experience as sound vary in
amplitude and frequency and correspondingly in perceived loudness and pitch. Decibels are the
measuring unit for sound energy.
The visible outer ear channels the sound waves through the auditory canal to the eardrum, a tight
membrane that vibrates with the waves. Transmitted via the bones of the middle ear (the hammer,
anvil, and stirrup) to the fluid-filled cochlea in the inner ear, these vibrations create movement in
tiny hair cells on the basilar membrane, triggering neural messages to be sent (via the thalamus)
to the auditory cortex in the brain. Damage to the hair cells accounts for most hearing loss.
ä Exercise: Locating Sounds
ä Transparency: 66 How We Locate Sounds
2. Describe how sounds are located.
Sound waves strike one ear sooner and more intensely than the other ear. We localize sounds by
detecting the minute differences in the intensity and timing of the sounds received by each ear.
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Module 12 The Other Senses
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Touch
ä Lecture: The Amazing Capabilities of Touch
ä Exercises: Two-Point Thresholds; Warm Plus Cold Equals Hot; Touch Localization
3. Describe the sense of touch.
Our sense of touch is actually four senses—pressure, warmth, cold, and pain—that combine to
produce other sensations, such as “hot.” There is no simple relationship between what we feel and
the type of specialized nerve ending found there. Only pressure has identifiable receptors.
Pain
ä Lectures: Cultural Differences in Pain; Pain Control
ä Exercise: The Revised Reducer–Augmenter Scale
ä Videos: Modules 20 and 21 of The Mind series, 2nd ed.: Phantom Limb Pain and Treating Chronic Pain; Programs 4
and 9 of Moving Images: Exploring Psychology Through Film: Brain Reorganization: Phantom Limb Sensations and
Firewalking: Mind Over Matter?
ä Transparency: 67 Biopsychosocial Approach to Pain
4. Explain the basis for pain.
Pain is an alarm system that draws our attention to some physical problem. Pain experiences vary
greatly, depending on our physiology, our experiences and attention, and our surrounding culture.
There is no one type of stimulus that triggers pain, and there are no special receptors for pain. At
low intensities, the stimuli that produce pain cause other sensations, including warmth or coolness,
smoothness or roughness. The gate-control theory of pain is that a “gate” in the spinal cord either
opens to permit pain signals traveling up small nerve fibers to reach the brain or closes to prevent
their passage. Pain is controlled through a combination of medical and psychological treatments.
Smell and Taste
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Lectures: Taste Preferences; Gender-Related Odors; Pheromones; Fragrance Effects
Exercises: Taste: The Basic Taste Sensations; Genetic Effects in Taste; Taste; Identifying Odors
Video: Segment 12 of the Scientific American Frontiers series, 2nd ed.: Tasters and Supertasters
Transparencies: 68 The Sense of Smell; 69 The Olfactory Brain
5. Describe the senses of taste and smell, and comment on the nature of sensory interaction.
Taste, a chemical sense, is a composite of sweet, sour, salty, bitter, and umami sensations and of
the aromas that interact with information from the taste buds. Taste buds on the top and sides of
the tongue contain taste receptor cells, which send information to an area of the temporal lobe not
far from where the brain receives olfactory information. Sensory interaction refers to the principle
that one sense may influence another, as when the smell of food influences its taste.
Smell is also a chemical sense, but without any basic sensations. The five million olfactory receptor cells recognize individual odor molecules, with some odors triggering a combination of receptors. The receptor cells send messages to the olfactory lobe, then to the temporal lobe and to parts
of the limbic system. An odor’s ability to spontaneously evoke memories is due in part to the close
connections between brain areas that process smell and those involved in memory storage.
Body Position and Movement
ä Lecture: The Remarkable Case of Ian Waterman
ä Exercises: Nystagmus; Vision and Balance
ä Video: Module 11 of The Brain series, 2nd ed.: Sensory-Motor Integration
6. Distinguish between kinesthesis and the vestibular sense.
Kinesthesis is the system for sensing the position and movement of individual body parts. Sensors
in the muscles, tendons, and joints are continually providing our brain with information. A companion vestibular sense monitors the head’s (and thus the body’s) position and movement. The biological gyroscopes for this sense of equilibrium are in the inner ear.