Transcript SENSATION - Ms. Kelly's AP Psychology Website

The process by which our sensory
systems receive stimuli from our
environment .
 Bottom-up processing – information
that enters our senses (eyes, ears, nose)
vs
 Top-down processing – information
processing which draws on our
experiences & expectations to interpret
incoming sensations. (Perception)
 Is the study of how the physical properties
of stimuli relate to people’s experience of
stimuli
 MEASURING THE SENSES
 1. The absolute threshold – is the
minimum amount of stimulation needed to
detect a stimulus 50% of the time.
 2. The difference threshold is the smallest
difference in stimulation that can be
detected 50% of the time (also called
jnd-just noticeable difference)
 The size of the just noticeable difference is
proportional to the strength of the original
stimulus.
Signal detection Theory
is used to predict when a weak signal
will be detected. A new theory that
assumes there is no absolute
threshold. Detection of a stimulus
depends on a combination of actors:
stimulus intensity, background
noise, a person’s level of experience,
motivation & physical condition.
 3.
 Diminished sensitivity as a result of
constant stimulation. You just get used to
the stimulus and don’t notice it anymore.
 SELECTIVE ATTENTION
Focusing our conscious awareness on a
particular stimulus (one stimulus at a time)
to the exclusion of others.
“the cocktail party effect”
 The visual system transduces light waves into
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neural impulses that the brain processes into what
we consciously see.
1. Cornea-transparent, protective outer membrane
of the eye.
2. Pupil-The small opening in the middle of the iris,
which changes size to let in different amounts of
light.
3. Iris-the colored part of the eye is a ring of muscle.
4. Lens-is located behind the pupil & iris and
adjusts its shape to focus light from objects near or
far away.
Retina is the light sensitive membrane
at the back of the eye. The retina contains
receptor cells called rods: allow you to
see black & white
 Cones: allow you to see color
 Bi-polar cells – neurons that connect the
rods & cones to the ganglion cells
 Ganglion cells – connect to the bipolar
cells. The bundled axons form the optic
nerve.
 Blind spot – the point where the optic
nerve leaves the eye & there are no rods or
cones.
 5.
 The optic nerve carries visual information to
the brain’s visual cortex, which lies in the
occipital lobe in the back of the brain.
 1. Tri-chromatic or Three color theory
 There are 3 primary colors: red, green &
blue. Any color we see is a combination of
the waves of these 3 colors.
 2. The opponent process theory
 Color processing works in the cones. There
are opposing pairs of red-green, blackwhite, blue-green Used to explain
afterimages
Depends on the presence of sound waveswhich are changes in pressure generated by
vibrating molecules.
Loudness depends on amplitude or height of
the sound wave.
Pitch depends on frequency of sound wavewhich is the number of times per second a
sound wave cycles from the highest to the
lowest point. The higher the frequency the
higher the pitch.
Place TheoryStates that sound waves of different
frequencies trigger receptors at
different places on the basilar
membrane. The brain figures out the
pitch of sound by detecting the
position of hair cells that send the
neural signal.
FREQUENCY THEORY
Sound waves of different frequencies
make the basilar membrane vibrate at
different rates & causes neural
impulses to be sent at different rates.
Pitch is determined by how fast the
neural signals move along to the
brain.
 CONDUCTION DEAFNESS - loss of
hearing as a result of structural
damage.
 NERVE DEAFNESS – damage to the
cochlea, hair cells,. This damage may
result from disease or prolonged
exposure to loud noise.
 The 5 tastes are: salty, sweet, sour,
bitter. & umami.
 Gustation refers to taste
 Smell occurs when chemicals are
inhaled into the nose. Smell receptors
send impulses along the olfactory
nerve to the brain.
 Kinesthesis is the sense &
movement of body parts.
 The vestibular sense is your sense
of equilibrium or body orientation.
 Touch-the sense of touch is a collection
of several senses
 Cold
 Pressure
 Warmth
 Pain
Warmth + Cold = Hot
 The theory that the spinal cord
contains a “gate” that blocks pain
signals or allows them to pass onto the
brain. The “gate” is opened by the
activity of pain signals traveling up
small nerve fibers and is closed by
activity in larger fibers or by
information coming from the brain.