Weitere ähnliche Inhalte
Ähnlich wie Chapter 3 (20)
Mehr von Los Angeles Southwest (20)
Kürzlich hochgeladen (20)
Chapter 3
- 1. Chapter 3
Sensation and Perception
This multimedia product and its content are protected under
copyright law. The following are prohibited by law:
Any public performance or display, including transmission of
any image over a network.
Preparation of any derivative work, including the extraction, in
whole or in part, of any images.
Any rental, lease or lending of the program.
Copyright © 2008 Allyn & Bacon
- 2. Chapter 3 Overview
The process of sensation
Vision
Hearing
Smell and taste
The skin senses
Balance and movement
Influences on perception
Principles of perception
Unusual perceptual experiences
Copyright © 2008 Allyn & Bacon
- 3. The Process of Sensation
Sensation is the process through
which the senses pick up visual,
auditory, and other sensory stimuli
and transmit them to the brain
Perception is the process by which
the brain actively organizes and
interprets sensory information
Copyright © 2008 Allyn & Bacon
- 4. What is the difference between
the absolute threshold and the
difference threshold?
What is the softest sound you can hear and
the dimmest light you can see?
How much must the volume be turned up or
down for you to notice a difference in the
loudness of music?
Researchers in sensory psychology have
performed many experiments to answer
these kinds of questions
Copyright © 2008 Allyn & Bacon
- 5. Absolute threshold
The minimum
amount of sensory
stimulation that can
be detected 50% of
the time
Copyright © 2008 Allyn & Bacon
- 6. Difference threshold
The smallest increase or decrease in a
physical stimulus required to produce a
difference in sensation that is noticeable
50% of the time
Just noticeable difference (JND) is the
smallest change in sensation that a person
is able to detect 50% of the time
Copyright © 2008 Allyn & Bacon
- 7. Weber’s Law
The JND for all senses depends on a
proportion or percentage of stimulus change
rather than on a fixed amount of change
– A 2% change is needed for a JND in a weight
you are holding
a 1 lb difference is needed for a JND in a 50 lb weight
a 2 lb difference is needed for a JND in a 100 lb weight
– Only a 0.33% change is needed for a JND in the
pitch of a sound
– Weber’s law best applies to people with average
sensitivities and to stimuli that are not too
strong or weak
Copyright © 2008 Allyn & Bacon
- 8. How does transduction enable the
brain to receive sensory
information?
Sensory receptors are highly specialized cells in
the sense organs that detect and respond to one
type of sensory stimuli and transduce (convert) the
stimuli into neural impulses
Transduction is the process through which
sensory receptors convert sensory stimulation into
neural impulses
Sensory adaptation is the process in which
sensory receptors grow accustomed to constant,
unchanging levels of stimuli over time
– e.g., Smokers grow accustomed to smell of cigarettes
Copyright © 2008 Allyn & Bacon
- 9. Vision
Our eyes respond to light in
the visible spectrum
– The band of electromagnetic
waves visible to the human
eye
Electromagnetic waves are
measured in wavelengths
– The distance from the peak of
a light wave to the peak of
the next wave
Copyright © 2008 Allyn & Bacon
- 10. How does each part of the eye
function in vision?
Cornea
– Tough, transparent
protective layer that
covers front of eye
– Bends light rays inward
through the pupil
Lens
– Transparent disk-
shaped structure behind
the iris and pupil
– Changes shape as it
focuses on objects at
varying distances
This process is called
Accommodation
Copyright © 2008 Allyn & Bacon
- 11. How does each part of the eye
function in vision?
Retina
– Contains sensory receptors
for vision
Rods
– Receptor cells that allow
eye to respond to low
levels of light
Cones
– Receptor cells that enable
us to see color and fine
detail
Fovea
– Area at center of retina
that provides the clearest
and sharpest vision
Blind spot
– Point in each retina where
there are no rods or cones
Copyright © 2008 Allyn & Bacon
- 12. What path does visual information
take from the retina to the primary
visual cortex?
Optic nerve
– Caries visual information
from each retina to both
sides of the brain
Primary visual
cortex
– Part of the brain in
which visual information
is processed
– Feature detectors
respond to specific
visual patterns, such as
lines or angles
Copyright © 2008 Allyn & Bacon
- 13. How do we detect the difference
between one color and another?
An apple’s skin looks red
because it absorbs short
wavelengths and reflects
long wavelengths
Hue
– The specific color perceived
Saturation
– The purity of a color
Brightness
– The intensity of the light
energy that is perceived as
a color
Copyright © 2008 Allyn & Bacon
- 14. What two major theories
attempt to explain color vision?
Trichromatic Theory
– Three types of cones in the retina each make a
maximal response to one of three colors- blue,
green, or red
Opponent-Process Theory
– Three kinds of cells respond by increasing or
decreasing their rate of firing when different
colors are present
Red/green cells
Yellow/blue cells
White/black cells
Copyright © 2008 Allyn & Bacon
- 16. Hearing
Sound requires a medium, such as air
or water, through which to move
First demonstrated by Robert Boyle in
1660
– Watch in a jar experiment
Copyright © 2008 Allyn & Bacon
- 17. What determines the pitch and
loudness of sound, and how is each
quality measured?
Frequency
– The number of cycles completed by a sound wave in one
second
– Determines the pitch of a sound
– Frequency is measured in hertz (Hz)
Amplitude
– The loudness of sound
– Amplitude is measured in decibels (dB)
Timbre
– The distinctive quality of a sound that distinguishes it from
other sounds of the same pitch and loudness
– Example: A piano and guitar sound different when playing
the same note
Copyright © 2008 Allyn & Bacon
- 18. Decibel levels of various sounds
Figure 3.5
The loudness of a sound (its
amplitude) is measured in
decibels. Each increase of 10
decibels makes a sound 10
times louder. A normal
conversation at 3 feet
measures
about 60 decibels, which is
10,000 times louder than a soft
whisper of 20 decibels. Any
exposure to sounds of 130
decibels or higher puts a
person at immediate risk for
hearing damage, but levels as
low as 90 decibels can cause
hearing loss if one is exposed
to them over long periods of
time.
Copyright © 2008 Allyn & Bacon
- 19. How do the outer ear, middle ear,
and inner ear function in hearing?
Outer ear
– Visible part of the ear,
consisting of the pinna and
auditory canal
Middle ear
– Contains the ossicles, which
connect the ear drum to the
oval window and amplify
sound waves
Inner ear
– Cochlea: Fluid filled chamber
that contains the basilar
membrane and hair cells
– Hair cells: Sensory receptors
for hearing
Copyright © 2008 Allyn & Bacon
- 20. What two major theories
attempt to explain hearing?
Place theory
– Each individual pitch is determined by the
particular location along the basilar membrane
of the cochlea that vibrates the most
– Provides a good explanation of how we hear
sounds with frequencies higher than 1000 Hz
Frequency theory
– Hair cell receptors vibrate the same number of
times per second as the wave sounds that reach
them
– Provides a good explanation of how we hear
low-frequency sounds
Copyright © 2008 Allyn & Bacon
- 21. Smell and Taste
Olfaction
– The sense of smell
Gustation
– The sense of taste
Copyright © 2008 Allyn & Bacon
- 22. What path does a smell message
take from the nose to the brain?
Olfactory epithelium
– Two 1-inch square patches
of tissue, one at the top of
each nasal cavity, which
contain olfactory
neurons
Olfactory bulbs
– Two structures above the
nasal cavity where smell
sensations first register in
the brain
Orbitofrontal cortex
– Receives messages from
olfactory bulbs via the
thalamus
Copyright © 2008 Allyn & Bacon
- 23. What are the primary taste
sensations, and how are they
detected?
Traditionally, four primary taste sensations
have been recognized
– Sweet
– Sour
– Salty
– Bitter
Recent research suggests that there is a
fifth taste sensation
– Umami
– This sensation is triggered by glutamate
Copyright © 2008 Allyn & Bacon
- 24. What are the primary taste
sensations, and how are they
detected?
Taste sensations are detected by receptor cells in the taste buds
Specialized receptors are activated by each flavor (sweet, sour,
etc.)
– These receptors send separate messages to the brain
Copyright © 2008 Allyn & Bacon
- 25. The Skin Senses
Include the senses of touch and pain
These senses are critical for survival
Copyright © 2008 Allyn & Bacon
- 26. How does the skin provide
sensory information?
When an object touches and depresses the
skin it stimulates receptors in the skin
These receptors send messages through
nerve connections to the spinal cord,
through the brainstem and midbrain, and to
the somatosensory cortex
Areas on the skin vary in sensitivity to
touch, as measured by the two-point
threshold
– Areas with greater sensitivity are more densely
packed with touch receptors
Copyright © 2008 Allyn & Bacon
- 27. What is the function of pain, and how is
pain influenced by psychological factors,
culture, and endorphins?
Pain serves as an early warning system for many
potentially deadly situations
Pain can be influenced by several psychological
factors
– Focusing attention elsewhere reduces pain
– Placebo effect reduces pain
– Negative thoughts increase pain
– Some cultures encourage individuals to suppress, or
exaggerate, emotional reaction to pain
Endorphins are the body’s natural painkillers
– They block pain and produce a sense of well-being
Copyright © 2008 Allyn & Bacon
- 28. Balance and Movement
The kinesthetic and vestibular
senses provide information about
where the parts of the body are and
where the body is located relative to
the physical environment
Copyright © 2008 Allyn & Bacon
- 29. What kinds of information do the
kinesthetic and vestibular senses
provide?
The kinesthetic sense provides
information about the position of body parts
in relation to each other and the movement
of the entire body or its parts
This information is detected by receptors in
the joints, ligaments, and muscles
Copyright © 2008 Allyn & Bacon
- 30. What kinds of information do the
kinesthetic and vestibular senses
provide?
The vestibular sense detects movement and the body’s orientation in space
The vestibular sense organs are located in the semicircular canals and
vestibular sacs in the inner ear
– These organs sense rotation of the head
Copyright © 2008 Allyn & Bacon
- 31. Influences on Perception
Perception is the process through
which the brain assigns meaning to
sensations
Perception is influenced by a number
of factors, including
– Attention
– Prior knowledge
– Cross-modal perception
Copyright © 2008 Allyn & Bacon
- 32. What is gained and what is lost
in the process of attention?
Attention is the process of sorting through
sensations and selecting some of them for further
processing
When attention is focused on some sensations,
others are missed altogether or misperceived
– Inattentional blindness occurs when attention is
shifted from one object to another and we fail to notice
changes in objects not receiving direct attention
– The cocktail party phenomenon shows that we focus
attention on information that is personally meaningful
Copyright © 2008 Allyn & Bacon
- 33. How does prior knowledge
influence perception?
Bottom-up processing
– Information processing in which individual bits of
data are combined until a complete perception is
formed
Top-down processing
– Information processing in which previous
experience and knowledge are applied to
recognize the whole of a perception
– Perceptual set is an expectation of what will
be perceived that can affect what is perceived
Copyright © 2008 Allyn & Bacon
- 34. How does information from
multiple sources aid perception?
Cross modal perception
– The process by which the brain integrates
information from more than one sense
– Cross modal perception is used to process
complex stimuli such as speech
Copyright © 2008 Allyn & Bacon
- 36. What are the principles that govern
perceptual organization?
Gestalt principles of perceptual organization
– Similarity: Objects that have similar characteristics are perceived as a unit
– Proximity: Objects that are close together are perceived as belonging together
– Continuity: Figures or objects are perceived as belonging together if they appear
to form a continuous pattern
– Closure: Figures with gaps in them are perceived as complete
F
Copyright © 2008 Allyn & Bacon
- 37. What are some of the binocular
and monocular depth cues?
Depth perception
– The ability to perceive the visual world in three
dimensions and to judge distances accurately
Binocular depth cues depend on both
eyes working together
– Convergence
– Binocular disparity
Monocular depth cues can be perceived
by one eye alone
Copyright © 2008 Allyn & Bacon
- 38. Binocular disparity
Enables most of us to see 3-D images in stereograms
Copyright © 2008 Allyn & Bacon
- 40. How does the brain perceive
motion?
The brain perceives real motion by
comparing the movement of images
across the retina to reference points
that it assumes to be stable
Autokinetic illusion
– An unmoving light in a dark room appears
to move
Your eyes are moving, not the light
In the dark, the brain has no stable reference
point to determine what is moving
Copyright © 2008 Allyn & Bacon
- 41. What are three types of
puzzling perceptions?
Ambiguous figures
– The perceptual system tries to resolve the uncertainty by
seeing the figure first one way and then another
Impossible figures
– May not seem unusual until you examine them closely and
see the impossibility
Copyright © 2008 Allyn & Bacon
- 42. What are three types of
puzzling perceptions?
Illusions
– False perceptions or misperceptions of an actual stimulus in the
environment
Figure c shows the Müller-Lyer illusion
Figure d shows the Ponzo illusion
Copyright © 2008 Allyn & Bacon
- 43. Unusual Perceptual
Experiences
Subliminal perception
– The capacity to perceive and respond to
stimuli that are presented below the
threshold of awareness
Extrasensory perception (ESP)
– Gaining information about objects,
events, or another person’s thoughts
through means other than known sensory
channels
Copyright © 2008 Allyn & Bacon
- 44. In what ways does subliminal
perception influence behavior?
Research suggests that subliminal
information can influence behavior to
some degree
– But it appears to be ineffective at
persuading people to buy products or
vote in certain ways
Copyright © 2008 Allyn & Bacon
- 45. What have studies of ESP
shown?
Some studies have suggested that ESP
exists
But, in almost all cases, attempts to
replicate these studies have failed
– So most psychologists remain skeptical
about existence of ESP
Copyright © 2008 Allyn & Bacon