Download How do we see in color?

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.
Your Senses
Vision, Hearing,
Smell, Taste, Touch
and Body Position
Touch
Touch (Somatosensation)
• Touch receptors are on
the skin
• Four basic skin senses
are
– Pain, warmth, cold,
and pressure
• All skin sensations are a
combination of these
four basic senses
• Burning = warmth +
cold + pain
Pain
• Why do we experience pain??
– Your body’s way of telling you something has
gone wrong
• Biopsychosocial Perspective on Pain
Biological Influence
• Activity in spinal cord
• Genetic differences in
endorphin production
• The brain’s interpretation
of CNS activity
Social-Cultural Influences
• Presence of others
• Empathy for others’ pain
• Cultural expectations
Psychological Influences
• Attention to pain
• Learning based on experience
• Expectations
Personal
Experience
Of Pain
Why do we feel Pain?
Gate-control Theory of Pain
• Pain messages travel on one set of nerve
fibers containing pain gates.
• The gates are open when pain is felt.
• Other sensory messages go through
another set of fibers.
• The nonpain fibers can close the pain
gates to stop the sense of pain.
Body Senses
Kinesthetic Sense
• The system for sensing the position and
movement of individual body parts
• Relies on receptor cells from the
muscles and joints
• One’s leg “falling asleep” is a disruption
of the kinesthetic sense
Vestibular Sense
• The system for sensing body orientation
and balance
• Relies on fluid in the semicircular canals
of the inner ear
• Spinning in circles disrupts the fluid.
Vision
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The Visual System
• Far more of the brain is devoted to vision
than to any other sense modality. Why?
– Enormous importance to our lives – more
than any other sense
– Human visual system is engaged in complex
processing activities
Vision
• Photoreceptors in our eyes
gather light
• Convert its physical energy
into neural messages
• And send it to the occipital
lobe in the brain for decoding
and analyzing
That’s basically
it….
Why Two Eyes?
• Produces binocular disparity
–Constructing three dimensional
world out of two dimensional retinal
images
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Vision
• How does our material
body construct our
conscious visual
experience?
• How do we transform
particles of light energy
into colorful sights?
Transduction
Conversion of one form of energy to
another.
Stimulus energies changed to neural impulses.
Light
Eyes
Transduction
Neural messages
How is this important when
studying sensation?
For example:
Light energy to vision.
Chemical energy to smell and taste.
Sound waves to sound.
What you
consciously see
We only use light energy to see.
What makes up a light wave?
Wavelength
• The distance from the peak of
one light wave to the peak of the
next.
•The distance determines the hue
(color) of the light we perceive.
Intensity
The amount of energy in a light wave.
Determined by the height of the wave.
The higher the wave the more intense
the light is. (brightness)
How do we see in color?
What color is this dragon?
Color
• The dragon is anything but red.
• The dragon rejects the long
wavelengths of light that to us are
red- so red is reflected of and we see
it.
• Also, light has no real color.
• It is just energy turned into color by
our eyes
• It is our mind that perceives the color.
What enables you to
perceive color??
Two major color theories
Young-Helmholtz Trichromatic
(three color) Theory
•Guessed that we have 3 different types of
photoreceptor cells in our eyes.
•Each with differing sensitivities to different
light wavelengths
• Realized that any color can be created by
combining the light waves of three primary colors
•Most colorblind people simply lack cone receptor cells for one
or more of these primary colors. – Not really blind – just limited in
what colors they can see
Click here to simulate color blindness
Opponent-Process Theory
• The visual system has receptors that
react in opposite ways to three pairs of
colors (red-green, blue-yellow, and
white-black).
– These are antagonist/ opponent colors.
– Light that stimulates one half of the pair
inhibits the other half
– Produces afterimages
Afterimages – colors perceived
after other, complementary colors
are removed
Afterimage Effect
Parallel Processing
• The processing of several aspects of a
problem simultaneously.
Color
Motion
Form
Depth
Feature Detection
The concept that specific nerve
cells in the brain respond to specific
features of the stimulus, such as
shape angle or movement.
Other Vision
Concepts
Hue
• The color of light as determined by the
wavelength of the light energy
• Includes: red, orange, yellow, green,
blue, indigo and violet (ROY G BIV)
• The eye can detect 7 million separate
hues
Amplitude
• The brightness of
light as determined
by height of the
wave
• The taller the wave,
the brighter the color
THE EYE
THE EYE- inside
Cornea
• The clear bulge on the front of the
eyeball
• Begins to focus the light by bending it
toward a central focal point
• Protects the eye
Parts of the Eye – Cornea
Iris
• A ring of muscle tissue that forms the
colored portion of the eye; creates a hole
in the center of the iris (pupil)
• Regulates the size of the pupil by
changing its size--allowing more or less
light to enter the eye
Parts of the Eye - Iris
Pupil
• The adjustable opening in the center of
the eye that controls the amount of light
entering the eye (surrounded by the iris)
• In bright conditions the iris expands,
making the pupil smaller.
• In dark conditions the iris contracts,
making the pupil larger.
Parts of the Eye - Pupil
Lens
• A transparent structure behind the pupil;
focuses the image on the back of the eye
(retina)
• Muscles that change the thickness of the
lens change how the light is bent
thereby focusing the image
• Glasses or contacts correct problems in
the lens’ ability to focus.
Parts of the Eye - Lens
Retina
• Light-sensitive surface with cells that
convert light energy to nerve impulses
• At the back of the eyeball
• Made up of three layers of cells
– Receptor cells
– Bipolar cells
– Ganglion cells
Parts of the Eye - Retina
Receptor Cells
• These cells are present in every sensory
system to change (transduce) some other
form of energy into neural impulses.
• In sight they change light into neural
impulses the brain can understand.
• Visual system has two types of receptor
cells – rods and cones
Rods
• Visual receptor cells located in the
retina
• Can only detect black and white
• Respond to less light than do cones
Cones
• Visual receptor cells located in the
retina
• Can detect sharp images and color
• Need more light than the rods
• Many cones are clustered in the
fovea.
Rods and Cones
Fovea
• The central focal point of the retina
• The spot where vision is best (most detailed)
Types of
Vision
Processing
Bipolar Cells
• Gather information
from the rods and
cones and pass it on
to the ganglion cells
• Cells that form the
middle layer in the
retina
Ganglion Cells
•Pass the information
from the bipolar cells
through their axons
•Together these cells
form the optic nerve.
•The top layer of the
cells in the retina
Visual Processing in the Retina
Visual Processing in the Retina
Visual Processing in the Retina
Visual Processing in the Retina
Optic Nerve
• The nerve that carries visual information
from the eye to the occipital lobes of the
brain
Parts of the Eye – Optic Nerve
Blind Spot
• The point at which the optic nerve
travels through the retina to exit the eye
• There are no rods and cones at this
point, so there is a small blind spot in
vision.
Parts of the Eye – Blind Spot
Hearing
Aka: Audition
Why do we have two ears?
Sound
• Sound, like light, comes in waves
• Sound is vibration
• Features of sound include:
– Pitch
– Hertz
– Decibels
Pitch
• A sound’s highness or lowness
• Dependent on the frequency of the
sound wave
• Is measured as hertz (Hz)
Hertz (Hz)
• A measure of the number of sound wave
peaks per second; measures “frequency”
• Determines the pitch of the sound
• Human hearing goes from 20 Hz to
20,000 Hz
Decibel (dB)
• A measure of the height of the sound
wave
• Determines the loudness of the sound
• Sometimes called amplitude
Amplitude is how loud the sound is. The higher
the crest of the wave is the louder the sound is. It
is measured in decibels.
Hearing:
The Structure of the
Auditory System
Parts of the Ear – Sound Waves
Auditory Canal
• The opening through which sound
waves travel as they move into the ear
for processing
• Ends at the tympanic membrane
(eardrum)
Parts of the Ear – Auditory Canal
Tympanic Membrane (eardrum)
• The tissue barrier that transfers sound
vibration from the air to the tiny bones
of the middle ear
• Can be damaged by objects in the ear or
exceptionally loud noises
Parts of the Ear – Tympanic
Membrane
Ossicles
• Three tiny bones that transfer sound
waves from the eardrum to the cochlea
• Hammer, anvil and stirrup
Parts of the Ear - Occicles
Cochlea
• A hearing organ where sound waves are
changed into neural impulses
• The major organ of hearing
• Filled with fluid; a snail shaped body tube
Cochlear
Implant
Parts of the Ear - Cochlea
Hair Cells
• The receptor cells for hearing in the
cochlea that change sound vibrations
into neural impulses
• Similar to the rods and cones within the
eye
Parts of the Ear - Hair Cells
Auditory Nerve
• The nerve that carries sound information
from the ears to the temporal lobes of
the brain
Parts of the Ear – Auditory Nerve
Semicircular Canals
• Organs in the inner ear used in sensing
body orientation and balance (vestibular
sense)
• Relies on fluid in the canals
• Spinning in circles disrupts the fluid.
Parts of the Ear – Semicircular Canals
Divisions of the Ear
• Ear’s structure can be divided into:
– The outer ear
– The middle ear
– The inner ear
Divisions of the Ear
Divisions of the Ear
Divisions of the Ear
How do we perceive
differences in pitch?
There are two theories……..
Place Theory
• We hear different
pitches because
different sound
waves trigger activity
at different places
along the cochlea’s
basilar membrane.
Frequency Theory
• We sense pitch by the basilar membrane
vibrating at the same rate as the sound.
• But this theory has trouble explaining high
pitch sounds because our hairs cannot
vibrate at certain speeds.
What about above our
absolute threshold??
Fact or Fiction??
Hearing loss
• Conduction Hearing Loss: caused by
damage to mechanical system of ear.
•Sensorinueral hearing loss: caused by
damage to cochlea’s receptor cells or to
auditory nerves.
Cochlea Implant
Smell and Taste
Why do we study smell and taste
together?
• SENSORY INTERACTION: the principle
that one sense may influence another.
Taste
• Taste is a chemical sense.
• Receptor cells are located primarily on
the tongue and in the mouth.
• Four different tastes:
– Salty, sweet, sour and bitter
• Damaged taste receptor cells are
replaced within a few days.
How do we taste?
•Taste (and smell) are
chemical senses.
What is the central muscle
involved in taste?
Taste Buds
Map out the tongue
Papillae
• Those bumps on our
tongue are called
Papillae.
• Papillae help grip
food while your teeth
are chewing.
• They also have
another special job they contain your
taste buds
TASTE
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PTC Strips
Supertasters
• People with an abundance of taste
receptors
• Approximately 25% of the population
Nontasters
• People with a minimum of taste
receptors
• Taste with less intensity than the rest of
the population
• Approximately 25% of the population
But what about smell?
Can our sense of smell
be biologically based?
Smell
• Smell is a chemical sense.
• Olfactory cells in the upper nasal
passages detect molecules in the air.
• Taste and smell interact to produce
flavor.
Olfactory Cells
• The chemical receptor cells for smell
• Located in the nasal passages
Gender related odors
• Can you smell the difference between?
So can we smell the difference?
• Well….yes and no.
Pheromones
•Chemical messengers that are picked up
through our sense of smell.
•Founded in the early 1930’s by studying
silkworms.
•Jury is still out on whether they exist in
humans.
The End