Transcript Sensation and Perception

Essentials of Psychology,
by Saul Kassin
CHAPTER 3:
Sensation and Perception
©2004 Prentice Hall Publishing
Sensation and Perception
Measuring the Sensory Experience
Sensation
Perception
Extrasensory Perception
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Sensation and Perception
• Sensation
– The processes by which our sense organs
receive information from the environment.
• Transduction
– The process by which physical energy is
converted into sensory neural impulses.
• Perception
– The processes by which people select,
organize, and interpret sensations.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Processes of Sensation & Perception
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Measuring Sensory Experience
Research and Theory
• Psychophysics
– The study of the relationship between
physical stimulation and subjective
sensations.
• Signal-Detection Theory
– The theory that detecting a stimulus is
jointly determined by the signal and the
subject’s response criterion.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Measuring Sensory Experience
Thresholds
• Absolute Threshold
– The smallest amount of stimulation that can
be detected.
• Just Noticeable Difference (JND)
– The smallest amount of change in a stimulus
that can be detected.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Measuring Sensory Experience
Absolute Sensory Thresholds
• Vision: A single candle flame from 30 miles on a
dark, clear night
• Hearing: The tick of a watch from 20 feet in total
quiet
• Smell: 1 drop of perfume in a 6-room apartment
• Taste: 1 teaspoon sugar in 2 gallons of water
• Touch: The wing of a bee on your cheek, dropped
from 1 cm
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Sensation
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Vision
Hearing
Other Senses
Keeping the Signals Straight
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
The Electromagnetic Spectrum
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
Structures of the Human Eye
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
Structures of the Human Eye
• Cornea
– Clear outer membrane that bends light to
focus it in the eye.
• Pupil
– The hole in the iris through which light
passes.
• Lens
– The structure that focuses light on the retina.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
The Retina
•The rear
of the eye
where
rods and
cones
convert
light into
neural
impulses.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
Visual Pathways
Optic Nerve
• Pathway that
carries visual
information
from the eyeball
to the brain.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
Hubel & Wiesel’s Experiment
• Hubel and Wiesel’s experiment measured the activity of
cells in a cat’s visual cortex.
• Cells in the visual cortex that respond only to certain
types of visual information, for example, a diagonal line
moving up and down, are called feature detectors.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
Trichromatic Theory
• T. Young (1802) & H.
von Helmholtz (1852)
both proposed that the
eye detects three
primary colors: red,
blue, & green.
• All other colors can be
derived by combining
these three.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
The Color Wheel
• Spectral colors vary
from violet-blue to red
– 470 to 700 nanometer
wavelength
• Opponent colors are
directly across from each
other on the wheel.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
Test of Color Deficiency
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Vision
Opponent-Process Theory
– Color vision is derived from three pairs
of opposing receptors. The opponent
colors are blue and yellow, red and
green, and black and white.
• This theory explains afterimages (a visual
sensation that persists after prolonged
exposure to and removal of a stimulus)
and color deficiency.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Hearing
The Human Ear
Audition
•The
sense of
hearing
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Hearing
Auditory Localization
– The ability to judge
from which direction a
sound is coming
• Sounds from different
directions are not identical
as they arrive at left and
right ears.
• The brain calculates a
sound’s location by using
differences in timing and
intensity.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Hearing
Common Sounds and the Noise They Produce
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Hearing
Hearing Disabilities
• Conduction Hearing Loss
– Caused by damage to the eardrum or bones
in the middle ear.
• Sensorineural Hearing Loss
– Caused by damage to the structures of the
inner ear.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Other Senses
Olfactory System
•Structures
responsible
for the
sense of
smell
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Other Senses
Taste
• Taste buds
– Nets of taste-receptor
cells
• This is a photograph of the
tongue’s surface (top), magnified
75 times.
• 10,000 taste buds line the tongue
and mouth.
• Children have more taste buds than
adults do.
• There are four primary tastes:
sweet, salty, sour, and bitter.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Other Senses
Temperature
• The Thermal Grill
When a person grasps
two braided water pipes
– one with cold water
running through it and
one with warm water –
the sensation is “burning
hot” and painful.
• There are two separate
pathways for warmth and
cold.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Other Senses
Pain
• Gate-control Theory
– Theory that the spinal cord contains a
neurological “gate” that blocks pain signals
from the brain when flooded by competing
signals.
• Psychological control
– Mind over sensation, distraction
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Other Senses
Coordination
• Kinesthetic System
– Structures distributed throughout body that
sense position and movement of body parts.
• Vestibular System
– The inner ear and brain structures that
afford a sense of equilibrium.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Keeping the Signals Straight
• Synesthesia
– Rare condition in which stimulation in one
sensory modality triggers sensations in
another sensory modality.
• Each sensory system is designed to operate
separately from the others.
• Sensory Adaptation
– A decline in sensitivity to a stimulus as a
result of constant exposure.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Perception
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Perceptual Organization
Perceptual Constancies
Depth and Dimension
Perceptual Set
The World of Illusions
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Perceptual Organization
Reversible Figures
– Drawings that one can
perceive in different
ways by reversing
figure and ground.
• Gestalt Psychology
– School of thought
rooted in the idea that
the whole is different
from the sum of its
parts.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Perceptual Organization
Gestalt Laws of Grouping
• Proximity
– Seeing 3 pair of lines in A
• Similarity
– Seeing columns of orange
and red dots in B
• Continuity
– Seeing lines that connect 1
to 2 and 3 to 4 in C
• Closure
– Seeing a horse in D
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Perceptual Organization
Identifying Objects
• Geons (geometric
icons) are simple 3D
component shapes.
• A limited number
are stored in
memory.
• Geons are combined
to identify essential
contours of objects.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Perceptual Constancies
• Size Constancy
– The tendency to view an object as constant
in size despite changes in the size of the
retinal image.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Depth and Dimension
• Depth Perception
– The use of visual cues to estimate depth and
distance.
• Convergence
– A binocular cue involving the turning
inward of the eyes as an object gets closer.
• Binocular Disparity
– A binocular cue whereby the closer an object
is, the more different the image is in each
retina.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Depth and Dimension
Monocular Depth Cues
– Distance cues that enable the perception of
depth with one eye.
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Relative Image Size
Texture Gradient
Linear Perspective
Interposition
Atmospheric Perspective
Relative Elevation
Familiarity
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Depth and Dimension
The Visual Cliff
• Devised by Eleanor
Gibson and Richard Walk
to test depth perception in
infants and animals.
• Provides visual illusion of
a cliff.
• Caregiver stands across
the gap.
• Babies are not afraid until
about the age that they
can crawl.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Perceptual Set
• What is seen in the center figures depends on the
order in which one looks at the figures:
– If scanned from the left, a man’s face is seen.
– If scanned from the right, a woman’s figure is seen.
• This demonstrates the effects of one’s perceptual set.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Perceptual Set
Context Effects
• The same physical
stimulus can be
interpreted differently
depending on
perceptual set, e.g.,
context effects.
• When is the middle
character the letter B
and when is it the
number 13?
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
The World of Illusions
The Müller-Lyer Illusion
– Illusion in which
the perceived
length of a line is
altered by the
position of other
lines that enclose it
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
Extrasensory Perception
• The Case for ESP
• The Case against ESP
• The Continuing Controversy
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
The Case for ESP
• Extrasensory Perception (ESP)
– The ability to perceive something without
ordinary sensory information.
– This has not been scientifically demonstrated.
• Parapsychologists distinguish between three
types of ESP:
– Telepathy – Mind-to-mind communication
– Clairvoyance – Perception of remote events
– Precognition – Ability to see future events
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
The Case against ESP
ESP Cards
• J. B. Rhine conducted many experiments on ESP
using stimuli such as these.
• Rhine believed that his evidence supported the
existence of ESP, but his findings were flawed..
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing
The Continuing Controversy
• The ganzfield procedure
• Researchers disagree about the reliability of
studies done to replicate the ganzfield test.
• Visit www.randi.org/ for information about
the James Randi Educational Foundation’s
million-dollar paranormal challenge.
Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing