Download Vision Transduction Sensory system converts energy into neural

Vision
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Transduction
○ Sensory system converts energy into neural
messages.
● Wavelength
○ Distance form wave peak to next wave peak
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Hue
○ Color we see
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Amplitude
○ Height of wave peak
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Intensity
○ Amount of energy in light waves. (influences
brightness)
● The retina
● Light travels through outer cells to buried inner cells
called rods and cones
● Rods and cones create neural signals to alert next
layer of cells the bipolar cells
● Bipolar cells activate ganglion cells that converge to
create optic nerve which carries all information to the
brain
● Optic nerve leaving the eye creates “blind spot” where no receptor cells can be
located
● Where image is focused on retina is called the fovea where only cones are
present
Rods
Cones
-Sensitive to dim light
-Many have own bipolar
-periphery of retina
cells
-120 million
-color vision
-Don’t have own bipolar
-6 million
cells
-centered in retina
-low sensitivity in dim light
● Visual processing
● Feature detectors
○ Certain cortical neurons that receive
visual info and respond to certain features of scene
● Parallel processing
○ Brains capability to process visual components at the same time (face
rather than just an eye or nose) –breaks down vision into subdimensions like color, depth, movement, and form.
● Color vision
● Young-Hemholz Trichromatic Theory
● Retina uses 3 color receptors, sensitive to green, red, or blue. When
combined we see other colors.
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● Herring: Opponent Process Theory
After leaving receptor cells visual info analyzed by opponent colors.
(red/green; blue/yellow; black/white)
Touch
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● 3 types of skin receptors
Mechanoreceptors: Respond to skin deformation
○ Skin indentation, vibration, hair movement
Thermoreceptors: Respond to change in temperature.
Nocioreceptors: Respond to painful stimuli
○ Mechanical or thermal stimuli near levels that can cause
tissue damage
Kinesthetic
● The kinesthetic senses relay specific information about muscle movement,
changes in posture, and strain on muscles and joints. They rely on feedback from
two sets of specialized nerve endings: stretch receptors, which are attached to
muscle fibers, and Golgi tendon organs, which are attached to the tendons.
● (Hint: The reason you can touch your fingers together with your eyes closed.)
Vestibular
● The vestibular senses control equilibrium and create an awareness of body
position. The receptors for these senses are located in the vestibular organs in
the inner ear. The sensation of body rotation stems from the three semicircular
canals of the inner ear. The sensation of gravitation and movement forward and
backward, as well as up and down, arises in the two vestibular sacs that lie
between the semicircular canals and the cochlea.
● (Hint: it sounds like the word stable and it helps keep your body balanced.)
Smell
● Molecules of substances diffused in air swirl into nasal
passage
● Odorants bind to receptors in the nostrils
● Olfactory cells are activated sending electric signals
toward olfactory bulb
● Signals transmitted to brain through olfactory bulb and
nerve
● Remarkable memory for certain smells
● Smell plays an integral role in the finer sense of taste
Hearing
● Converts objective stimuli of vibrating
airwaves into sounds
● Amplitude of waves determine loudness
● Frequency of waves determine pitch
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○ Short= high pitch , Long= low pitch
Vibrations enter ear canal and hit eardrum (tympanic membrane)
Eardrum moves hammer, anvil, and stirrup
Stirrup vibrates oval window, forcing fluid in cochlea to flow
Fluid in cochlea flows past hair cells lining basilar membrane
Hair cells convert fluid movements into nerve impulses
Nerve impulses are brought to brain by auditory nerve
Ear is split into outer, middle, and inner ear
Outer ear: Contains ear canal and pinna
Middle ear: Contains bones of middle ear and eardrum
Inner ear: Contains cochlea and auditory nerve
Place Theory: Different pitches caused by sound waves triggering certain areas
of cochlea
Frequency Theory: Different pitches caused by brain reading frequency of
neural impulses traveling along auditory nerve
Conduction Hearing Loss: Hearing loss due to problems with mechanical
system, causing vibration conduction to diminish
Sensorineural Hearing Loss: Hearing loss due to damage to cochlea’s hair cell
receptors or associated nerve cells
Cochlear implant translates sounds to electric signals to help restore hearing
Taste
● Taste is the body’s ability to react to different flavors of objects.
● There are five basic flavors: Sweet Salty Bitter Sour Umami
● Taste is detected and determined by cluster of cells on the tongue called taste
buds.
● Different tastes are detected on different areas of the tongue.
● Our desire for good tasting foods has evolutionary benefit. Because our
ancestors acquired a taste for protein and energy rich food this served as a
natural way for humans to develop a healthy diet. Conversely, the aversion to the
bitter tastes of certain foods served as a way to keep early humans from eating
poisonous or harmful foods.
● Taste is also heavily influenced by smell. This is why it helps to plug your nose
before eating a food you don’t like.
● Taste is influenced by our expectations as well. If told that a food is bad people
are more likely to taste it this way. Also if people are told that wine is more
expensive than it really is makes it taste better.
Thresholds
● Absolute threshold- The minimum stimulation necessary to detect a particular
stimulus
○ Stimulus needed to detect stimulation 50% of the time
● Signal detection theory- no single absolute threshold but our senses adapt to
environment
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Example women react more easily to crying baby in the night than other sounds
because crying baby is more important.
Difference Thresholds- minimum difference person can detect between any two
stimuli 50% of the time.
Webers law difference threshold not constant amount but proportion of stimulus.
○ lights must differ by an intensity of 8% for difference to be detected
Much attention has been drawn to the idea of subliminal stimulation whether it
can be used in advertisement or if it used to send messages in songs played
backwards.
○ People can unconsciously process information however it does not
manipulate or control us.
Sensory adaptation- after a certain amount of time people sense a stimulus less
than they did before.
This allows us to focus on stimuli that actually changes.
Cale- Smell and hearing
Jake- Vision and touch
Tommy- Kinesthetic and vestibular
Ryan- Taste, thresholds, and compiling