Transcript Sensation and Perception

Sensation and Perception
Sensation: your window to the world
Perception: interpreting what comes
in your window.
Transduction
• Transforming
signals into
neural
impulses.
• Information
goes from the
senses to the
thalamus ,
then to the
various areas
in the brain.
Sensory Adaptation
• Decreased
responsivene
ss to stimuli
due to
constant
stimulation.
Do you feel your underwear
all day?
Cocktail-party phenomenon
• The cocktail party
effect describes the
ability to focus one's
listening attention on a
single talker among a
mixture of
conversations and
background noises,
ignoring other
conversations.
• Form of selective
attention.
Energy v. Chemical senses
Energy Senses
Chemical Senses
Phase One: Gathering Light
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The height of a wave gives us it’s intensity (brightness).
The length of the wave gives us it’s hue (color).
ROY G BIV
The longer the wave the more red.
The shorter the wavelength the more violet.
Phase Two: Getting the light in
the eye
Vision
• Our most dominating
sense.
• Visual Capture: refers to our
tendency to allow visual images to
dominate our perception. For
example, when we watch a movie in
a theater, we tend to think that the
voices we hear come from the
moving images on the screen,
rather than from the speakers that
could be located all around the
theater.
Path of light through the eye
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Cornea When light first enters the eye, it passes through the cornea,
which is a protective clear covering over the pupil and the iris. The light
bends as it passes through and begins to make an image.
Pupil The light then passes through the pupil, a dark HOLE in the center
of the iris (IRIS IS A MUSCLE), which is the colored portion of the eye.
The pupil regulates light entry into the inner eye and brings objects into
focus.
Lens The light continues to travel through to the lens of the eye. The
lens is a clear, flexible structure that focuses the image onto the retina.
It is flexible so that it can focus images that are close up or far
away….misshapen lens = you need glasses
Retina The light and images are then focused on the retina, which is a
layer of light-sensitive cells at the back of the eye. It is made up of two
kinds of photoreceptor cells: cones/color and rods. The cones respond
to bright light and color and also transmit sharp images. The
concentration of cones is low on the sides of the retina and increases as
the cones approach the center of the retina. The rods are more
sensitive to light and are more numerous than cones.
0ptic Nerve The image is then sent to the optic nerve at the back of the
eye. The optic nerve receives the signals from the retina, then sends
them to the brain.
Phase Three: Transduction
Transduction Continued
Order is:
1. Rods/Cones to
2. Bipolar to
3. Ganglion to
4. Optic Nerve.
Sends info to thalamusThen sent to cerebral
cortex
• 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 process by which specialized
nerve cells in the brain
respond to specific features of
a visual stimulus, such as lines,
edges, angle, or movement .
• Parallel Processing - ability
of the brain to simultaneously
process incoming stimuli of
differing quality
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.
• The trichromatic color theory began in the 18th
century, when Thomas Young proposed that color
vision was a result of three different
photoreceptor cells.
• Hermann von Helmholtz later expanded on
Young's ideas using color-matching experiments
which showed that people with normal vision
needed three wavelengths to create the normal
range of colors.
Opponent-Process theory
The sensory receptors
come in pairs.
• Red/Green
• Yellow/Blue
• Black/White
• If one color is stimulated,
the other is inhibited.
Since one color produces an excitatory
effect and the other produces an
inhibitory effect, the opponent colors are
never perceived at the same time (the
visual system cannot be simultaneously
excited and inhibited).
• While the trichromatic theory defines the
way the retina of the eye allows the
visual system to detect color with three
types of cones, the opponent process
theory accounts for mechanisms that
receive and process information from
cones
Afterimages – result of cones
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.
2Then 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
• Sent then to thalamus up auditoryIt is all about the vibrations!!!
nerve.
Path of sound
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Sound waves enter through the outer ear/pinna
Sound waves move through the ear canal
Next sound waves strike the eardrum, causing it to vibrate
Vibrations enter the middle ear
Hammer picks up the vibrations, vibrations are passed to the
anvil, to the stirrup
Vibrations are now in the inner ear
V vibrations are channeled to the cochlea, lined with cilia
Then nerve cells detect vibrations and convert them to
electrical impulses
These electrical impulses are transmitted to the brain
The brain, through the thalamus, and temporal/auditory
association cortex interprets electrical impulses as sound.
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 would not know you are
sitting in a chair which is on the
ground.