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Gender, age, and experience influence our
Figure 1.6-25 Processes ability to identify and remember scents. Women
Taste, smell, and memory taste
tend to have a better sense of smell, but for all of
Information from the taste buds us, the sense of smell peaks in early adulthood
travels to an area between the
brain’s frontal and temporal lobes and gradually declines thereafter ( Doty, 2001 ;
(yellow area). It registers in an Wickelgren, 2009 ; Wysocki & Gilbert, 1989 ). Phys-
area not far from where the brain ical condition also matters: Smokers and people
receives information from our with Alzheimer’s disease, Parkinson’s disease, or
sense of smell (red area), which
interacts with taste. The brain’s alcohol use disorder typically have a diminished
circuitry for smell also connects sense of smell ( Doty, 2001 ). Moreover, the smells
with areas involved in memory we detect and the ways we experience them dif-
Distributed by Bedford, Freeman & Worth Publishers. Not for redistribution.
storage, which helps explain why Processes smell
a smell can trigger a memory. (near memory area) fer, thanks to our individual genes ( Trimmer et al.,
2019 ). The scent of a flower may be different for
you than for a friend.
Copyright © Bedford, Freeman & Worth Publishers.
Body Position and Movement

1.6-15 How do we sense our body’s position and movement?
1.6-15 How do we sense our body’s position and movement?
If you did not sense your body’s position and movement, you could not put food in
your mouth, stand up, or reach out and touch someone. Nor could you perform the
“simple” act of taking one step forward. That act requires feedback from, and instruc-
tions to, some 200 muscles, and it engages brain power that exceeds the mental activity
involved in reasoning. Millions of position and motion sensors in muscles, tendons, and
joints all over your body, called proprioceptors, provide constant feedback to your brain.
This enables your sense of kinesthesis which keeps you aware of your body parts’ posi-

,

tion and movement. Twist your wrist one degree and your brain receives an immediate
update.
If you are able to experience sight and sound, you can momentarily imagine being
blind and deaf by closing your eyes and plugging your ears to experience the dark silence.
But what would it be like to live without touch or kinesthesis — without being able to sense
the positions of your limbs when you wake during the night? Ian Waterman of Hampshire,
England, knows. At age 19, Waterman contracted a rare viral infection that destroyed the
nerves enabling his senses of light touch and of body position and movement. People with
this condition report feeling disembodied, as though their body is dead, not real, not theirs
( Sacks, 1985 ). With prolonged practice, Waterman learned to walk and eat — by visually
focusing on his limbs and directing them accordingly. But if the lights went out, he would
crumple to the floor ( Azar, 1998 ).
Vision interacts with kinesthesis for you, too. If you are able, stand with your right heel
in front of your left toes. Easy. Now close your eyes and try again. Did you wobble?

A companion vestibular sense monitors your head’s (and thus your body’s) position
and movement. The biological gyroscopes for this sense of equilibrium are two structures in
kinesthesis [kin-ehs-THEE- your inner ear. The first, your fluid-filled semicircular canals, look like a three-dimensional

sis] our movement sense; our pretzel ( Figure 1.6-18a ). The second structure is the pair of calcium-crystal–filled vestibular
system for sensing the position sacs. When your head rotates or tilts, the movement of these organs stimulates hair-like

and movement of individual receptors, which send nerve signals to your cerebellum at the back of your brain, enabling
body parts.
you to sense your body position and maintain your balance.
vestibular sense our balance If you twirl around and then come to an abrupt halt, neither the fluid in your semicir-
sense; our sense of body
movement and position that cular canals nor your kinesthetic receptors will immediately return to their neutral state.
enables our sense of balance. The dizzy aftereffect fools your brain with the sensation that you’re still spinning. This
illustrates a principle that underlies perceptual illusions: Mechanisms that normally give

152 Unit 1 Biological Bases of Behavior

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