Transcript Sensation and Perception

Sensation
Sensation: your window to the world
Perception: interpreting what comes
in your window.
Sensation
 Our sensory
and
perceptual
processes
work
together to
help us sort
out complex
processes
Sensation
 Bottom-Up Processing
 analysis that begins with the sense receptors and
works up to the brain’s integration of sensory
information
 Top-Down Processing
 information processing guided by higher-level
mental processes
Sensation- Basic Principles
 Psychophysics
 study of the relationship between physical
characteristics of stimuli and our
psychological experience of them
 Light- brightness
 Sound- volume
 Pressure- weight
 Taste- sweetness
Sensation- Thresholds
 Absolute Threshold
 minimum stimulation needed to detect a
particular stimulus 50% of the time
 Difference Threshold
 minimum difference between two stimuli
required for detection 50% of the time
 just noticeable difference (JND)
Sensation- Thresholds
 Signal Detection Theory
 predicts how and when we detect the presence of a
faint stimulus (signal) amid background stimulation
(noise)
 assumes that there is no single absolute threshold
 detection depends partly on person’s
 experience
 expectations
 motivation
 level of fatigue
Signal Detection Theory
• Absolute thresholds are
not really absolute.
• Things like motivation or
physical state can effect
what we sense.
• False Positives
• False Negatives
My wife could sleep through a war, but if
of our dog barks, she is up!!!
Sensation- Thresholds
100
Percentage
of correct
detections
 Subliminal
75
50
Subliminal
stimuli
25
0
Low
Absolute
threshold
Intensity of stimulus
Medium
 When stimuli are
below one’s
absolute threshold
for conscious
awareness
Sensation- Thresholds
 Weber’s Law- to perceive as different, two
stimuli must differ by a constant minimum
percentage
 light intensity- 8%
 weight- 2%
 tone frequency- 0.3%
 Sensory adaptation- diminished sensitivity
as a consequence of constant stimulation
Weber’s Law
• Computes the Just
Noticeable Difference
(JND)
• The change needed is
proportional to the original
intensity of the stimulus.
• The more intense the
stimulus the more change is
needed to notice the
difference.
• 8% for vision.
Transduction
• Transforming signals
into neural impulses.
• Information goes
from the senses to
the thalamus , then
to the various areas
in the brain.
Remember Ethan in Sky High. He
changes his body to slime. Solid
form to liquid form. Change from
one form of energy to another.
Click the picture to watch power
placement.
Sensory Adaptation
• Decreased
responsiveness to
stimuli due to
constant stimulation.
Do you feel your underwear all day?
Energy v. Chemical senses
Energy Senses
Chemical Senses
Vision
• Our most dominating
sense
• Visual Capture
Phase One: Gathering Light
• The height of a wave gives us it’s intensity
(brightness).
• The length of the wave gives us it’s hue (color).
• The longer the wave the more red.
• The shorter the wavelength the more violet.
Phase Two: Getting the light in
the eye
Phase Three: Transduction
Transduction Continued
• Order is Rods/Cones to
Bipolar to Ganglion to
Optic Nerve.
• Sends info to thalamusarea called lateral
geniculate nucleus (LGN).
• Then sent to cerebral
cortexes.
• Where the optic nerves
cross is called the optic
chiasm.
Phase Four: In the Brain
• Goes to the Visual
Cortex located in
the Occipital Lobe
of the Cerebral
Cortex.
We have specific cells that see
the lines, motion, curves and
other features of this turkey.
These cells are called feature
detectors.
• Feature Detectors.
• Parallel Processing
Color Vision
Two Major Theories
Trichromatic Theory
Three types of cones:
• Red
• Blue
• Green
• These three types of
cones can make millions
of combinations of
colors.
• Does not explain
afterimages or color
blindness well.
Opponent-Process theory
The sensory receptors
come in pairs.
• Red/Green
• Yellow/Blue
• Black/White
• If one color is
stimulated, the other
is inhibited.
Afterimages
Hearing
Our auditory sense
We hear sound WAVES
• The height of the wave gives us the amplitude of the
sound.
• The frequency of the wave gives us the pitch if the sound.
The Ear
Transduction in the ear
• Sound waves hit the eardrum then anvil
then hammer then stirrup then oval
window.
• Everything is just vibrating.
• Then the cochlea vibrates.
• The cochlea is lined with mucus called
basilar membrane.
• In basilar membrane there are hair cells.
• When hair cells vibrate they turn vibrations
into neural impulses which are called
organ of Corti.
• Sent then to thalamus up auditory nerve.
Pitch Theories
Place Theory and Frequency Theory
Place Theory
• Different hairs vibrate
in the cochlea when they
different pitches.
• So some hairs vibrate
when they hear high and
other vibrate when they
hear low pitches.
Frequency Theory
• All the hairs vibrate
but at different
speeds.
Deafness
Conduction Deafness
• Something goes wrong
with the sound and the
vibration on the way to
the cochlea.
• You can replace the
bones or get a hearing
aid to help.
Nerve (sensorineural)
Deafness
• The hair cells in the cochlea
get damaged.
• Loud noises can cause this
type of deafness.
• NO WAY to replace the hairs.
• Cochlea implant is possible.
Touch
• Receptors located in
our skin.
• Gate Control Theory
of Pain
Taste
• We have bumps on our
tongue called papillae.
• Taste buds are
located on the papillae
(they are actually all
over the mouth).
• Sweet, salty, sour and
bitter.
Vestibular Sense
• Tells us where our
body is oriented in
space.
• Our sense of
balance.
• Located in our
semicircular canals
in our ears.
Kinesthetic Sense
• Tells us where our
body parts are.
• Receptors located in
our muscles and
joints.
Without the kinesthetic sense
you could touch the button to
make copies of your buttocks.