SENSATIONProcess of taking in stimuli from the

environment

Smallest amount of stimulus that can detected at least half the time

Vision:1 candle flame,30 miles away on a dark night

Hearing: tick of watch at 20 feetTaste:1 teaspoon of sugar in 2 gallons of waterSmell:1 drop of perfume in a 3-room apartmentTouch: wing of bee, on your cheek from 1 cm.

ABSOLUTE THRESHOLD:

WOULD YOU NOTICE ONE CANDLE 30 MILES AWAY ON A DARK NIGHT?

http://commons.wikimedia.org/wiki/File:Einzelne_Kerze.JPG

Signal Detection Theory:No absolute thresholds, because it is affected by other factors like attention, expectations, motivations, emotions

Smallest difference between 2 stimuli that a person can detect at least 50% of the time

Just-noticeable difference (jnd)

Weber’s Law: the difference threshold increases in proportion to the original stimuli

Vision: 8%8 more candles to 100 candles to notice that

it’s brighter

DIFFERENCE THRESHOLD:

Decreasing sensitivity to unchanging stimuli-can focus attention on what’s important-lose delicious smell at the coffee shop after a while

http://commons.wikimedia.org/wiki/File:HK_Central_Mid-Level_Caine_Road_Starbucks_Coffee_Shop.JPG

SENSORY ADAPTATION:

Converting environmental stimuli into neural impulses

-senses gather energy/chemicals from environment

-must be converted into electrochemical energy so that neurons can carry the information to the brain to be processed

TRANSDUCTION:

Vision-light waves

Hearing-sound waves

Touch-pressure, temperature, pain

ENERGY SENSES:

-light waves

Most important sense for humans-rely

on it the most

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Visual capture: tendency for vision to dominate other senses

VISION:

PROCESS OF VISION:

http://commons.wikimedia.org/wiki/File:Anatomy_and_physiology_of_animals_How_light_travels_from_the_object_to_the_retina_of_the_eye.jpg

THE EYE:

http://upload.wikimedia.org/wikipedia/commons/2/27/Retinal_anatomy.jpg

LIGHT IS REFLECTED OFF OF

OBJECTS AND ENTERS THE EYE

IT PASSES THROUGH THE PROTECTIVE

COVERING OF THE CORNEA

IT ENTERS THROUGH THE PUPIL (BLACK

OPENING) WHICH IS CONTROLLED BY

THE IRIS (COLORED MUSCLE)

LIGHT IS FOCUSED (ACCOMODATION) ON THE RETINA BY

THE LENS ACCORDING TO

DISTANCE

RETINA RECEIVES THE LIGHT UPSIDE

DOWN AND INVERTED

TRANSDUCTION OCCURS IN THE

RETINA

Photoreceptors: cells sensitive to light 3 Layers in retina:1.-Rods: black/white/nighttime vision-in

peripheral vision -Cones: color vision, best acuity,

concentrated in fovea (center of retina)2. Bipolar cells: activate 3rd layer3. Ganglion cells: connect to optic nerve=Transduction (light to neural impulse)

RETINA:

Optic nerve carries

messages into the brain-where leaves the brain

is blind spot

Optic chiasm: half of each optic

nerve goes to the opposite hemisphere

Thalamus: routes the visual information to

the visual cortex in the occipital

lobe

http://commons.wikimedia.org/wiki/File:Constudeyepath.gif

ROY G BIV- VISIBLE SPECTRUM-determined by light’s wavelength

Theories:1.Trichromatic theory: 3 types of

photoreceptors: red, green, blue2. Opponent-process theory: colors come in

opposite pairs (afterimages, colorblindness)

COLOR VISION:

http://commons.wikimedia.org/wiki/File:Spectrummasthead.jpg

HEARING (Audition):

-sound wavesPitch=frequency of wavesLoudness=amplitude of waves

http://commons.wikimedia.org/wiki/File:HumanEar.jpg

Outer ear

collects and

amplifies

sounds

Tympanic membra

ne (eardrum) vibrates with the sound waves

Ossicles (3 bones in middle

ear) vibrate

and activate the Oval Window

Oval window vibrates

the cochlea (transduction happens

here)

Hair cells inside

cochlea activate the

auditory nerve which

carries messages to the thalamus

Thalamus sends

message to auditory cortex in

the occipital

lobe

Conduction deafness: loss of hearing due to inability to carry sound to inner ear (punctured eardrum, ossicles)-hearing aid

Sensorineural deafness: loss of hearing due to damage in the cochlea or auditory nerve-cochlear implant

DEAFNESS:

-sensitive to tactile sensations: pressure, warmth, cold, pain

-all other sensations are combination of these 4

-transductionhappens in skin receptors locatedall over the body

TOUCH (SOMATOSENSATION):

http://commons.wikimedia.org/wiki/File:LeftHand_2.png

Parietal lobe Sensitivity of body part=larger section of

cortex-is also inverted, top

controls the bottom of the body

SOMATOSENSORY CORTEX:

http://commons.wikimedia.org/wiki/File:Sensory_Homunculus.png

-associated with substance P-natural pain killers are endorphins-adaptive=causing damage, stop it

Gate-control theory: theory to explain pain-must go through gate in spinal cord-only most important pains go through-scratch=no longer itch

PAIN:

TASTE (GUSTATION): tastebud receptors-5 tastes: sweet, salty, sour, bitter, umami-supertasters: most tastebuds

SMELL (OLFACTION): receptors in nostril-only sense to not travel to thalamus 1st

-goes to limbic system=memory and emotion

Sensory interaction: work together to create sensation

CHEMICAL SENSES:

Kinesthesis: body position sense-know where body parts are and movements

Vestibular sense: sense of balance-in inner ear-semicircular canals

BODY SENSES:

http://upload.wikimedia.org/wikipedia/commons/2/23/Balance_beam_GMM.jpg