Process 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 feet Taste:1 teaspoon of sugar in 2 gallons of water Smell:1 drop of perfume in a 3-room apartment Touch: wing of bee, on your cheek from 1 cm.

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

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

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

 Vision-light waves  Hearing-sound waves  Touch-pressure, temperature, pain

- light waves Most important sense for humans-rely on it the most  Visual capture: tendency for vision to dominate other senses

my_and_physiology_of_animals_How_light_trave ls_from_the_object_to_the_retina_of_the_eye.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 3 rd layer 3. Ganglion cells: connect to optic nerve =Transduction (light to neural impulse)

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 ile:Constudeyepath.gif

 ROY G BIV- VISIBLE SPECTRUM -determined by light’s wavelength Theories: 1.Trichromatic theory: 3 types of photoreceptors: red, green, blue 2. Opponent-process theory: colors come in opposite pairs (afterimages, colorblindness) i/File:Spectrummasthead.jpg

-sound waves Pitch=frequency of waves Loudness=amplitude of waves

Outer ear collects and amplifies sounds Tympanic membrane (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

-sensitive to tactile sensations: pressure, warmth, cold, pain -all other sensations are combination of these 4 -transduction happens in skin receptors located all over the body

 Parietal lobe  Sensitivity of body part=larger section of cortex -is also inverted, top controls the bottom of the body ki/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

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 1 st -goes to limbic system=memory and emotion Sensory interaction: work together to create sensation

Kinesthesis: body position sense -know where body parts are and movements Vestibular sense: sense of balance -in inner ear-semicircular canals media.org/wikipedi a/commons/2/23/ Balance_beam_GM M.jpg