Invitation to Psychology

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ept Map

224 Chapter 6 Sensation and Perception

Chapter 6

Sensation and

p

erception

Measuring the Senses

Sensation is the detection and direct experience of physical energy as a result of

environmental or internal events.

Perception is the process by which sensory impulses are organized and interpreted.

• Sensation begins with the sense receptors, which convert the energy of a
  stimulus into electrical impulses that travel along the nerves to the brain.


• Anatomical codes (as set forth by the doctrine of specific nerve energies)
  and functional codes in the nervous system account for separate sensations.
  In rare cases, however, sensory crossover results in synesthesia.

The stimulus for hearing (audition)

is a pressure wave or the release of

compressed air.

Measuring the Senses

What We Hear

• Intensity corresponds to the experience of
  loudness.


• Frequency corresponds to the experience
  of pitch.


• Complexity corresponds to the experience
  of timbre.

The receptors for hearing are hair cells

(topped by cilia) embedded in the basilar

membrane of the organ of Corti, in the

interior of the cochlea.

Sensory Adaptation

• Psychologists specializing
  in psychophysics have
  studied sensory sensitivity
  by measuring absolute and
  difference thresholds.


• Signal-detection theory
  holds that responses in a
  detection task consist of
  both a sensory process and
  a decision process and

The Problems With Reward

motivation, alertness, and

expectations.

• Sensory adaptation occurs
  when sensation is unchanging.


• Sensory deprivation occurs
  with too little stimulation.

Sensing Without Perceiving

• We use selective attention to avoid
  sensory overload.


• Inattentional blindness is a failure
  to consciously perceive something
  you are looking at because you are
  not attending to it.

Hearing

Vision

What We See

Visual Receptors

• Wavelength of light
  produces the experience
  of hue.


• Intensity of light
  produces the experience
  of brightness.


• Complexity of light
  produces the experience
  of saturation.

Gestalt Principles

Gestalt principles—

such as figure and

ground, proximity,

closure, similarity, and

continuity—describe

visual strategies used by

the brain to perceive

form, distance, and

depth.

Depth and Distance

Perception

• Binocular cues
  include convergence
  and retinal
  disparity.


• Monocular cues
  include light and
  shadow; interpostion;
  motion parallax;
  relative size; texture
  gradients; relative
  clarity; and linear
  perspective.

Constancies and

Illusions

• Perceptual
  constancy is the
  accurate perception
  of objects as stable
  despite changes in
  size, shape, location,
  brightness, and
  color.


• Perceptual illusions
  occur when sensory
  cues are misleading
  or we misinterpret
  them.

Visual receptors are located in the retina of the eye and send signals

to the ganglion cells and ultimately to the optic nerve.

• Rods are responsible for vision in dim light.


• Cones are responsible for color vision.


• Rods and cones take time to adjust to dim illumination, a process
  known as dark adaptation.


• Information from rods and cones is processed and communicated
  by ganglion cells, the axons of which converge to form the optic
  nerve.


• Feature-detector cells in the visual areas of the brain detect
  specific aspects of the environment, such as line orientation.


• Separate groups of brain cells are especially responsive to faces,
  places, and bodies.

Color Vision

• The trichromatic theory
  accounts for the first level of
  color processing, which occurs
  in the retina, where three types
  of cones respond to different
  wavelengths of light.


• The opponent-process theory
  accounts for the second level of
  color processing, in which
  opponent-process cells in the
  retina and thalamus respond in
  opposite fashion to short and
  long wavelengths of light.

The stimulus for vision is light,

which travels in waves.