Sensation- Day 2
Review Questions:
1. Define sensation and perception, and
discriminate between the two.
2. What is the retina, and what happens
there?
3. Describe the basic idea behind the
Trichromatic Theory of color vision?
4. Distinguish between bottom-up
processing and top-down processing, and
give an example of each.
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
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.
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.
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
http://bookworm.com.sg/e-book-preview/e-science-10-senses-pg05-pic04b.gif
PTC Strips
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
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 1930’s by studying
silkworms.
•Jury is still out on whether they exist in
humans.
Body Senses
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.
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
• Tells us where our
body is oriented in
space.
• Our sense of balance.
• Located in our
semicircular canals in
our ears.
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.
The End