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SENSATION. Process of taking in stimuli from the environment. ABSOLUTE THRESHOLD:. 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
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SENSATION Process of taking in stimuli from the environment
ABSOLUTE THRESHOLD: 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? 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
DIFFERENCE THRESHOLD: 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
SENSORY ADAPTATION: 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
TRANSDUCTION: 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
ENERGY SENSES: • Vision-light waves • Hearing-sound waves • Touch-pressure, temperature, pain
VISION: -light waves Most important sense for humans-rely on it the most http://commons.wikimedia.org/wiki/File:Cranach,_Lucas_d.J._-_Lucretia_-_Detail_face.JPG • Visual capture: tendency for vision to dominate other senses
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
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 layer 3. Ganglion cells: connect to optic nerve =Transduction (light to neural impulse)
COLOR VISION: • 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) http://commons.wikimedia.org/wiki/File:Spectrummasthead.jpg
HEARING (Audition): -sound waves Pitch=frequency of waves Loudness=amplitude of waves http://commons.wikimedia.org/wiki/File:HumanEar.jpg
DEAFNESS: 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
TOUCH (SOMATOSENSATION): -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 http://commons.wikimedia.org/wiki/File:LeftHand_2.png
SOMATOSENSORY CORTEX: • Parietal lobe • Sensitivity of body part=larger section of cortex -is also inverted, top controls the bottom of the body http://commons.wikimedia.org/wiki/File:Sensory_Homunculus.png
PAIN: -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
CHEMICAL SENSES: 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
BODY SENSES: Kinesthesis: body position sense -know where body parts are and movements Vestibular sense: sense of balance -in inner ear-semicircular canals http://upload.wikimedia.org/wikipedia/commons/2/23/Balance_beam_GMM.jpg