Invitation to Psychology

COn

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ept Map

Chapter 6 Sensation and Perception 225

Chapter 6

Sensation and

p

erception

Other Senses

Taste Smell

Taste (gustation) is a

chemical sense.

• Papillae on the
  tongue contain taste
  buds, which contain
  taste receptors.


• The basic tastes are
  each produced by a
  different type of
  chemical: salty, sour,
  bitter, and sweet.
  Some consider umami
  to be a fifth basic
  taste, but this is
  controversial because
  in most foods its taste
  is not perceptible.


• Genetic and cultural
  differences influence
  responses to a
  particular taste.

Pain

Pain is both a skin sense and an internal sense.

• The gate-control theory holds that the experience of pain depends on
  whether neural impulses get past a “gate” in the spinal cord and reach
  the brain.


• In the gate theory, the brain can generate pain even in the absence of
  signals from sensory neurons, because an extensive matrix of neurons
  in the brain gives us a sense of our own bodies. When the matrix
  produces abnormal activity, the result is pain.

A leading explanation of phantom pain is that the brain has reorganized

itself, incorrectly interpreting messages from certain neurons as coming

from a nonexistent body part.

The Environment

Kinesthesis tells us where

our body parts are located.

Equilibrium tells us the

orientation of the body as

a whole, and relies on

three semicircular canals

in the inner ear.

Smell (olfaction) is also

a chemical sense.

• There are up to 1,000
  different kinds of
  receptors.


• Distinct odors activate
  unique combinations
  of receptors.


• Cultural and indivi-
  dual differences affect
  people’s responses to
  odors.

Senses of the Skin

These senses include

touch (pressure),

warmth, cold, and pain

and variations such as

itch and tickle.

“Gate” closed by

incoming

impulses from

large fibers or

from the brain;

opened by

impulses from

smaller fibers

If “gate” is open,

then pain

impulses reach

the brain

Input from

spinal cord

Memories

Emotions

Expectations

Attention

Signals from

brain centers

Abnormal patterns

of activity in a

neural matrix

Perceptual Powers

Inborn Abilities Psychological

Influences

on Perception

• Visual cliff experiments
  show that even at 6
  months, babies have
  depth perception.


• Without certain
  experiences during
  critical periods,
  perception is
  impaired.
  
  
  • Psychological
    influences on
    perception include
    needs, beliefs,
    emotions, and
    expectations (which
    produce perceptual
    sets).
  
  
  • These influences are
    affected by culture.
  
  
  
  

Perception Without Awareness

• In studies of subliminal perception, a person is exposed to explicit or subliminal information and is later tested to see whether
  the information affects behavior or performance.


• When simple stimuli are used, exposure to subliminal stimuli in the laboratory can influence various behaviors, judgments,
  and motivational states.


• However, no evidence of subliminal persuasion has been found with commercially marketed subliminal ads and recordings.

Pain