Sensation- Day 2Sensation- Day 2Review 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?

SoundSound

• Sound, like light, comes in waves

• Sound is vibration

• Features of sound include:

– Pitch

– Hertz

– Decibels

PitchPitch

• 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)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 CanalAuditory 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)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

OssiclesOssicles

• Three tiny bones that transfer sound waves from the eardrum to the cochlea

• Hammer, anvil and stirrup

Parts of the Ear - Occicles

CochleaCochlea

• 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 CellsHair 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 NerveAuditory Nerve

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

Parts of the Ear – Auditory Nerve

Semicircular CanalsSemicircular 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 EarDivisions 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 TheoryPlace Theory

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

Frequency TheoryFrequency 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.

TasteTaste

• 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

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PTC Strips

But what about smell?

Can our sense of smell be biologically based?

SmellSmell

• 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 CellsOlfactory 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 SenseKinesthetic 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 SenseKinesthetic 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 SenseVestibular 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