sensation_and_perception

Bellringer

• Why do you believe that people

put so much more trust in

evidence we have

seen

than

evidence we have

heard

? Give at

Vision

Main Objective:

Light:

• Light is electromagnetic energy.

– Humans can only see small parts of this spectrum.

• Described in wavelengths.

• Light can be broken down into a prism.

– Red (longest wavelength)

– Orange

– Yellow – Green

– Blue

– Indigo

The Eye:

• Light enters eye. Amount of light

determined by size of

pupil

.

What accounts for differences in size

of pupil???

• In bright light:

– Smaller…since bright enough that only need

small amount of light.

• In dark:

– Larger, since need to let in as much light as possible.

FYI:

• Studies show that most people usually feel

that the

wider open the pupils

, the

friendlier a person looks.

• This is because

interest in another person

Then What’s Next??

• Light then encounters the

lens

– Adjusts to the distance of objects by changing its thickness.

Read the following OUTLOUD! (REMAIN IN YOUR SEAT)

• Changes in lens project image onto the

retina

:

– Sensitive surface in the eye that acts like a the film in a camera.

– The “film” consists of neurons that are called

photoreceptors:

Overall Path of Vision:

Write on Eye Diagram

• In the human eye, light travels

through the pupil to the lens and is

then reflected onto the retina. The

optic nerve sends the visual

The Blind Spot:

• Blind spot

:

Demonstration

:

– Take out piece of paper and draw 2 circles (about size of dime) 4 inches apart.

– Hold your drawing at arm’s length, cover your

left eye, and stare at the circle on the left with your right eye.

– Then, move your drawing slowly towards your face until the circle on the right seems to

vanish.

– Reverse this experiment by covering your

right eye and stare at the circle on the right

Rods and

C

o

n

e

s

:

• Two kinds of photoreceptors

:

– Rods & Cones

– Rods:

• Sensitive to only brightness of light • Allow us to see in black and white

– EX: Movie theater, objects lose color before outlines

fade from view.

– Cones:

Eye/Brain trick warmup

What do you think???

• How many different shades of color can

the average person with normal color

Answer

!

• About a million!!!

Did you Know??

• Western cultures:

– Black associated with evil; death

• Egypt:

– Black has positive connotations

• Japan:

– Coffins draped with white and mourners wear white.

• Buddhist:

– Yellow is color of death

• Germans & Americans:

– Find blue soothing

• Spaniards:

Dark & Light Adaptation:

• Dark Adaptation

:

– Adjustment to lower lighting.

– EX: Entering a dark movie theater.

• Improves up to 45 minutes.

• Light Adaptation

:

– Adjustment to bright light.

• EX: Turning lamp on in the

Visual Acuity:

•

Visual Acuity:

– The sharpness of vision.

– Snellen Vision Chart

• Nearsighted:

– Cannot see objects far away.

• Farsighted:

– Cannot see objects close up.

Color Vision:

• Color Circle

– Colors across from each other are

complementary:

• If LIGHT is mixed, then form gray.

• If pigments, paints/crayons,

Cones and Color Vision:

• Cones are sensitive to

:

– Blue

– Green

– Red

• When more than one color stimulated at

same time, then perceive other colors.

Afterimages:

• Afterimage

:

Color Blindness:

• Due to absence of, or malfunction in, the

cones.

• Total color blindness

: VERY RARE!

– See in black and white

• Partial color blindness

:

– Red-green color blindness is common!

Bellringer

• How accurate would you rate your hearing

on a scale of 1 to 10?

• Do you listen to loud music in your car?

Headphones?

Hearing

Main Objective:

Hearing:

Vibrations are called a

Every sound has its own

pitch

and

loudness

:

• Pitch

:

– How high or low the sound is.

– The higher the frequency, the higher the pitch.

• EX: Women’s voices are higher in pitch due to

• Loudness

:

– The height or amplitude of sound waves. – Higher the amplitude, the louder the sound. – Measured in decibels (dB)

• Absolute threshold:

– Zero dB: ticking of watch 20 feet away in quiet room.

Path of Sound Waves:

• Eardrum

vibrates when sound strikes it.

• As it vibrates, it transmits the sound to 3

small bones in middle ear: the

hammer

,

the

anvil

, the

stirrup

(smallest bone in

body)…these bones vibrate and transmit

sound to

inner ear

, which consists of the

cochlea

.

– A bony tube that contains fluids as well as neurons that move in response to the

Path of Sound Waves (cont’d)

• Movement generate neural impulses that

are transmitted to the brain via the

auditory nerve

.

Locating Sounds:

• You can use information from vision and

other cues in locating the source of

sounds.

Deafness:

• About

2 million Americans

are deaf.

Conductive Deafness:

• Occurs because of damage to middle ear.

– Middle Ear: Amplifies sound

• Prevents people from hearing sounds that

are

not

loud enough!

Sensorineural Deafness:

• Deafness that results from damage to the

auditory nerve…damage to

inner ear

.

• Usually, neurons in cochlea are destroyed.

– Disease

– Prolonged exposure to very loud sounds.

Can you help Sensorineural

Deafness??

• Cochlear implants

or “

artificial ears

”

contain microphones that sense sounds

and stimulates

auditory nerve

.

– However, if auditory nerve damaged, then

cannot help.

A Cochlear

Implant story…

Deafness in the World Today

:

• Heather Whitestone

(1995 Miss America)

– http://www.youtube.com/watch?v=pyLBF6w900Q

• Interpreters

Other Senses:

Bellringer

• What are some ways that you cope with

physical pain?

• How high would you rate your pain

tolerance 1-10?

Main Objective:

What other senses???

• Smell

• Taste

Smell

:

• Dogs

:

– Use 7x of cerebral cortex for smell.

Smell (cont’d)

• Receptors

high in

each

nostril

.

– Receptors send information about the odors to the brain via the olfactory nerve.

• The nerve that transmits information about odors from olfactory receptors to the brain.

Taste:

• Neat fact

:

– Dogs can taste sweetness, and cats cannot!

• 4 basic taste qualities

:

– Sweet, sour, bitter, salty.

• OLD PEOPLE

:

• Taste is sensed through receptor neurons

on

taste buds

on tongue.

– If low sensitivity: Add sugar to food/drinks.

• Can be inherited.

• Burned your tongue???

– Kill taste cells BUT usually reproduce within a week!

The Skin Senses:

Pressure

Temperature

Pressure:

• Hairs on body

:

– Sensory receptors located around the roots of hair cells fire when skin is touched.

• More sensitive areas of body

:

– Fingertips, lips, nose, cheeks.

• WHY????

• Adaptation to pressure

:

Temperature

:

• Normal body temperature:

– 98.6*F

• Receptors are found

just below the skin

.

• Adaptation to temperature:

Pain

:

• It’s adaptive

:

– Motivates us to STOP!

• Some areas of body more sensitive to

others

:

– More pain receptors, then more sensitive to pain.

Pathway of Pain:

1.

Pain originates at the

point of contact

.

2.

Pain messages then to

spinal cord

to

thalamus

in brain.

3.

Then, projected to

cerebral cortex

,

when person registers

location

and

severity

of pain.

• Prostaglandins: Chemicals that help body

transmit pain messages to brain.

• Aspirin/ibuprofen help reduce

• Simple remedy to reduce pain:

– Scratching; Rubbing

• Why do we do this???

– Gate Theory: The suggestion that

only a certain amount of information can be processed by the nervous system at a given time.

– Rubbing/scratching area transmits sensations to brain that compete with pain messages.