Sensation and Perception
Chapter 3
Sensation
The process of detecting a physical stimulus,
such as light, sound, heat, or pressure.
Perception
The process of integrating, organizing, and
interpreting sensation.
Sensory Receptors
Specialized cells unique to each sense organ
that respond to a particular form of sensory
stimulation
Transduction
The process by which a form of physical
energy is converted into a coded neural
signal that can be processed by the nervous
system
Absolute Threshold
The smallest possible strength of a stimulus
that can be detected half the time.
Difference Threshold
The smallest possible difference between two
stimuli that can be detected half the time;
also called just noticeable difference.
Weber’s Law
A principle of sensation that holds the size of
the just noticeable difference will vary
depending on its relation to the strength of
the original stimulus
Sensory Adaption
The decline in sensitivity to a constant
stimulus
Subliminal perception
The perception of stimuli that are below the
threshold of conscious awareness
Wavelength
The distance from on wave peak to another
Cornea
A clear membrane covering the visible part of
the eye that helps gather and direct
incoming light
Pupil
The opening in the iris that change size to let
in different amounts of light
Iris
The colored part of the eye, which is the
muscle that controls the size of the pupil
Iridology
A pseudoscience based on the unproven
notion that the physical and psychological
functioning of an individual is represented
in marking of the iris
Lens
A transparent structure located behind the
pupil that actively focuses, or bends, light as
it enters the eye
Accommodation
The process by which the lens changes shape
to focus incoming light so that it falls on the
retina
Retina
A thin, light-sensitive membrane located at
the back of the eye that contains the sensory
receptors for vision.
Rods
The long, thin light-sensitive membrane
located at the back of the eye that contains
the sensory receptors for vision and night
vision
Cones
The short, thick, pointed sensory receptors of
the eye that detect color and are responsible
for color vision and visual acuity
Fovea
A small area in the center of the retina,
composed entirely of cones, where visual
information is most sharply focused.
Optic Disk
Area of the retina without rods or cones where
the optic nerve exits the back of the eye
Blind spot
The point at which the optic nerve leaves the
eye; producing a small gap in the field of
vision
Ganglion cells
In the retina, the specialized neurons that
connect to the bipolar cells, the bundled
axons of the ganglion cells form the optic
nerve
Bipolar cells
In the retina, the specialized neuron that
connects the rods and cones with the
ganglion cells.
Optic nerve
The thick nerve that exits from the back of the
eye and carries visual information to the
visual information to the visual cortex in the
brain
Optic Chiasm
Point in the brain where the optic nerve fibers
from each eye meet and partly cross over to
the opposite side of the brain
Trichormatic theory of color
vision
The theory that the sensation of color results
because of the cones in the retina are
especially sensitive to either red light, green
light,or blue light
Color blindness
One of several inherited forms of color
deficiency or weakness in which an
individual cannot distinguish between
certain colors
Afterimage
A visual experience that occurs after the
original source of stimulation is no longer
present
Opponent-process theory of color
vision
The theory that color vision is the product of
opposing pairs of color receptors, red/green,
blue/yellow, and black/white; when one
member of color pair is stimulated the other
is not
Audition
The technical term for hearing
Loudness
The intensity (or amplitude) of a sound wave,
measured in decibels
Amplitude
The intensity or amount of energy of a wave,
reflected In the height of the wave; the
amplitude of a sound determines loudness
Decibel
The unit of measurement for loudness
Pitch
The relative highness or lowness of a sound,
determined by the frequency of a sound
wave.
Frequency
The rate of vibration, or the number of sound
waves per second
Timbre
The distinctive quality of a sound, determined
by the complexity of a sound wave
Outer Ear
The part of the ear that collects sound waves;
consists of the pinna, the ear canal, and the
eardrum
Eardrum
A tightly stretched membrane at the end of the
ear canal that vibrates when hit by sound
wave
Middle ear
The part of the ear that amplifies sound
waves, consist of three small bones, the
hammer, the anvil, and the stirrup
Inner Ear
The part of the ear where sound is transduced
into neural impulses; consist of the cochlea
and semicircular canals
Cochlea
The coiled, fluid-filled inner-ear structure that
contains the sensory receptors for sound
Basilar Membrane
The membrane within the cochlea of the ear
that contains the hair cells
Hair cells
The hair like sensory receptors for sound,
found in the basilar membrane of the
cochlea
Frequency theory
The view that the basilar membrane vibrates
at the same frequency as the sound wave
Place theory
The view that different frequencies cause
larger vibrations at different locations along
the basilar membrane
Olfaction
Technical name for the sense smell
Gustation
Technical name for the sense of taste.
Olfactory bulb
The enlarged ending of the olfactory cortex at
the front of the brain where the sensation of
smell is registered
Pheromones
Chemical signals released by an animal that
communicates information and affect the
behavior of other animals of the same
species
Taste buds
The specialized sensory receptors for taste
that are located on the tongue and inside the
mouth and throat
Pain
The unpleasant sensation of physical
discomfort or suffering that can occur in
varying degrees of intensity
Gate-control theory
The theory that pain is a product of both
physiological and psychological factors that
cause spinal gates to open and relay patterns
of intense stimulation to the brain, which
perceives them as pain.
Substance P
A neurotransmitter that is involved in the
transmission of pain messages to the brain
Kinesthetic sense
The technical name for the sense of location
and position of body parts in relation to one
another
Proprioceptros
Sensory receptors, located in the muscles and
joints, that provide information about body
position and movement.
Vestibular sense
The technical name for the sense of balance,
or equilibrium.
ESP (extrasensory perception)
Perception of information by some means
other than through the normal process of
sensation
Parapsychology
The scientific investigation of claims of
paranormal phenomena and abilities
Bottom-up processing
Information processing that emphasizes the
importance of the sensory receptors in
detecting the basic features of a stimulus in
the process of recognizing a whole pattern;
also called data-driven processing
Top-down processing
Information processing that emphasizes the
importance of the observer’s knowledge,
exceptions, and other cognitive processes,
in arriving at meaningful perception;
analysis that moves from the whole parts;
also called conceptually driven processing
Gestalt psychology
a school of psychology founded in Germany
in the early 1900s that maintained that our
sensations are actively processed according
to consistent perceptual rules that result in
meaningful whole perceptions
Figure-ground relationship
A Gestalt principle of perceptual organization
that states that we automatically separate
the elements of a perception into the feature
that clearly stands out and its less distinct in
the background
Depth perception
The use of visual cues to perceive the distance
or three-dimensional characteristics of
objects
Monocular cues
Distance or depth cues that can be processed
by either eye alone
Binocular cues
distances or depth cues that require the use of
both eyes
Perceptual cues
The tendency to perceive objects, especially
familiar objects, as constant and unchanging
despite changes in sensory input
Size constancy
The perception of an object as maintaining the
same shape regardless of the image
produced on the retina
Shape constancy
The perception of an object as maintaining the
same shape regardless of the image
produced on the retina
Brightness constancy
The perception that the brightness of an object
remains the same even though the lighting
conditions change
Perceptual illusion
The misperceptions of the true characteristics
of an object or an image
Muller-Lyer Illusion
A famous visual illusion involving the
misperception of the identical length of two
lines, one with an arrow pointed inward,
one with an arrow pointed outwards
Moon illusion
A visual involving the misperception that the
moon is larger when it is on the horizon
than when is directly overhead
Perceptual set
the influence of prior assumptions and
exceptions on perceptual interpretations.
KEY PEOPLE
Karl Duncker
German Gestalt psychologist who is best
known for his studies on the perception of
motion; also studies the perception of pain
and the effect of past experience on
perception.
Max Wertheimer
German psychologist who founded Gestalt
psychology in the early 1900s, immigrated
to the United States in 1933, studied the
optical illusion of apparent movement, and
described principles of perception