Sensation- Day 2

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Sensation- Day 2

• Review Questions
• Define sensation and perception, and discriminate
  between the two.
• What is the retina, and what happens there?
• Describe the basic idea behind the Trichromatic
  Theory of color vision?
• Distinguish between bottom-up processing and
  top-down processing, and give an example of each.

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Hearing

• Aka Audition

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Why do we have two ears?
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Sound

• Sound, like light, comes in waves
• Sound is vibration
• Features of sound include
• Pitch
• Hertz
• Decibels

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Pitch

• A sounds highness or lowness
• Dependent on the frequency of the sound wave
• Is measured as hertz (Hz)

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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

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Decibel (dB)

• A measure of the height of the sound wave
• Determines the loudness of the sound
• Sometimes called amplitude

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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.
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Hearing The Structure of the Auditory System
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Auditory Canal

• The opening through which sound waves travel as
  they move into the ear for processing
• Ends at the tympanic membrane (eardrum)

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Parts of the Ear Auditory Canal
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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

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Parts of the Ear Tympanic Membrane
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Ossicles

• Three tiny bones that transfer sound waves from
  the eardrum to the cochlea
• Hammer, anvil and stirrup

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Parts of the Ear - Occicles
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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
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Parts of the Ear - Cochlea
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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

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Parts of the Ear - Hair Cells
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Auditory Nerve

• The nerve that carries sound information from the
  ears to the temporal lobes of the brain

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Parts of the Ear Auditory Nerve
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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.

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Parts of the Ear Semicircular Canals
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Divisions of the Ear

• Ears structure can be divided into
• The outer ear
• The middle ear
• The inner ear

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Divisions of the Ear
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Divisions of the Ear
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Divisions of the Ear
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How do we perceive differences in pitch?

• There are two theories..

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Place Theory

• We hear different pitches because different sound
  waves trigger activity at different places along
  the cochleas basilar membrane.

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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.

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Hearing loss

• Conduction Hearing Loss caused by damage to
  mechanical system of ear.

• Sensorinueral hearing loss caused by damage to
  cochleas receptor cells or to auditory nerves.

Cochlea Implant
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Smell and Taste
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Why do we study smell and taste together?

• SENSORY INTERACTION the principle that one sense
  may influence another.

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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.

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Tongue
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Taste Buds
Map out the tongue
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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

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TASTE
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PTC Strips
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But what about smell?

• Can our sense of smell be biologically based?

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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.

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Olfactory Cells

• The chemical receptor cells for smell
• Located in the nasal passages

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So can we smell the difference?
Pheromones

• Chemical messengers that are picked up through
  our sense of smell between males and females
• Founded in the early 1930s by studying
  silkworms.
• Jury is still out on whether they exist in
  humans.

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Body Senses
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Kinesthetic Sense

• Tells us where our body parts are.
• Receptors located in our muscles and joints.

Without the kinesthetic sense you could not touch
the button to make copies of your buttocks.
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Kinesthetic Sense

• The system for sensing the position and movement
  of individual body parts
• Relies on receptor cells from the muscles and
  joints
• Ones leg falling asleep is a disruption of the
  kinesthetic sense

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Vestibular Sense

• Tells us where our body is oriented in space.
• Our sense of balance.
• Located in our semicircular canals in our ears.

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Parallel Processing

• The processing of several aspects of a problem
  simultaneously.

Motion
Form
Color
Depth
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Feature Detection

• The concept that specific nerve cells in the
  brain respond to specific features of the
  stimulus, such as shape, angle, or movement.

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The End