Sensation & perception 6-8%
sensation & perception 6-8%
people:
gustav fechner – fechner’s law
david hubel & torsten wiesel – vision nobel
prize, feature detectors
ernst weber – weber’s law
torsten wiesel – sensory deprivation (seeing) long term effects
sensory transduction (stimuli signals transformed into neural impulses),
sensory adaptation (decreased responsiveness), sensory habituation (how fouced we are about them), cocktail-party phenomenon (involuntarily pay attention), sensation (activation of senses like eyes & ears), perception (understanding sensations)
vision (dominant sense) –
light intensity = how bright appears
light wavelength = hue we see (longer than we can see are infrared, microwaves, radio waves; shorter are ultraviolet & x-rays) – longest to shortest – roy g. biv; objects color appearance b/c reflect that wavelength
eye – cornea (protects & helps focus the light), pupil (muscles are iris – dilate to let more light in), accomodation (process of focusing light), lens (curved & flexible to focus), image is flipped upside down and inverted & then projected on retina (screen on back of eye)
transduction – (translate incoming stimuli into neural signals – other senses as well) happens when light activates neurons in retina including cones (activated by color, more in center of retina) & rods (black & white, more 20 to 1, peripheral, night vision), fovea centralis (lots of cones, focus spot), next bipolar cells activated, then ganglion
cells fire, axons of ganglion cells = optic nerve – send impulses to thalamus part called the lateral geniculate nucleus (lgn) – then sent to visual cortex in occipital lobe, blind spot (optic nerve leaves retina – no rods or cones) optic nerve – 2 parts to diff hemispheres, optic chiasm (where nerves cross each other)
inside brain – impulses activate feature detectors (groups of neurons in visual cortex that respond to diff types of visual images) ex: vertical lines/curves/motion, visual impairment
theories of color
trichromatic -(cones detect blue, red, green),
opponent-process theory – red/green, blue/yellow, black/white sensory receptors in
pairs – if one is stimulated, its pair is inhibited from firing – explains dichromatic color blindness, monochromatic color blindness (only gray), afterimages
hearing – sound waves & transduction
amplitude – height of wave (loudness – decibels)
frequency – length of wave (pitch –
megahertz), high-pitched = high freq = waves densely packed together
ear parts – pinna (outer ear), ear canal/auditory canal, eardrum/tympanic membrane, ossicles bones (hammer/malleus, anvil/incus, stirrup/stapes), oval window, cochlea (snail shell w/fluid), basilar membrane (floor of cochlea), lined w/hair cells (connected to organ of corti – neurons activated by hair cells movement), fluid moves = hair cells move = transduction, impulses to brain via auditory nerve
pitch theories
place theory – hair cells respond to diff freq
of sound based on where located in cochlea (upper tones)
frequency theory – lower tones – rate at
which cells fire – hair cells fire at diff rate (freq) in the cochlea
deafness
conduction deafness (problem conduction sound to cochlea)
nerve/sensorineural deafness – hair cells damaged (by loud noise) – don’t regenerate
touch – some nerve endings respond to pressure, others temp, nerve ending concentrated in certain areas, if touch or temp receptors stimulated sharply then pain receptors will also fire
gate-control theory – pain messages high priority so nerve “gates” swing wide open and shut for low priority messages – allow you to focus on message, endorphins (brain pain killers) & opiates (morphine) also swing gate shut
chemical senses (taste & smell)
taste/gustation – chemicals in food absorbed by taste buds on tongue (located on papillae – bumps on tongue), types – sweet, salty, sour, bitter, & maybe umami, some taste buds respond more intensely to specific taste and more weakly to others, more densly packed taste buds = more chemicals absorbed = more intense tasting food, food flavor = combination of taste & smell
smell/olfaction – chemicals emitted by substances
nose, nostril, mucous membrane, absorbed by olfactory receptor cells, olfactory bulb straight to limbic system of brain (amygdala and hippocampus – emotion and memory = powerful trigger for memories), anosmia (burnt out receptors), pheromones (natural chemicals), context driven
body position senses
vestibular senses – how body is oriented in space by 3 semicircular canals filled w/fluid in inner ear (provide feedback on body orientation), if fluid moves so much brain receives confusing signals = dizziness & nausea
kinesthetic sense – feedback on position and orientation of specific body parts (arm, leg), receptors in muscles and joints send info to brain
perception –
psychophysics (study interaction b/w sensations receive and experience of them)
absolute threshold – smallest amount of stimulus we can detect
subliminal stimuli (below absolute threshold) – most messaging not scientifically supported
difference threshold/just noticeable difference (smallestamount of change needed in a stimulus before we detect a change)
weber’s law (computes jnd) – change needed is proportional to the original intensity of stimulus)
weber’s constants differ for senses – hearing 5%, vision 8%
perceutual theories
signal detection theory – takes into account how
motivated we are to detect certain stimuli & what expect to perceive (factors caled response criteria/receiver operating characteristics), false positive – think perceive stimulus that is not there
false negative – no perceiving stimulus that is present
top-down processing – perceive by filling in gaps in what we sense (use background knowledge to help)
schemata (mental representations of how expect the world to be) create perceptual set (predispostion of perceiving something in certain way) – backmasking (70s b/c expected bad messages); makes you vulnerable to illusions
bottom-up processing/feature analysis – use only features of the object itself to build a complete perception – put characteristics together to get perception of object – automatic process – feature detectors in visual cortex – longer but more accurate
culture & experience influence perception – perceptual set, context effects
role of attention
rules of visual perception & optical illusions
figure-ground relationship – figure vs
background
gestalt rules – perceive images as groups not isolated elements
proximity – close = group
similarity – similar = group
continuity – continuous form = group
closure – fill in gaps = group
constancy
size (closer = bigger but know same object)
shape (diff angles/diff view but know same
object)
brightness – see as being constant color even as light reflects off object diff
perceived motion
stroboscopic effect – flip books – series of pics
phi phenomenon – lights turning on/off see motion
autokinetic effect – spot on light on wall in dark room – stare at – appears to move
depth cues & depth perception
eleanor gibson & visual cliff experiment
monocular cues – linear perspective, relative size cue, interposition cue (blocks other object = must be closer), texture gradient, shadowing
binocular cues – binocular
disparity/retinal disparity (closer object more disparity b/w images from each eye), convergence (closer to face – eyes move towards each other to keep focus)
muller-lyer illusion – lines w/arrows
esp (6th sense) – no scientific proof – telepathy, clairvoyance, precognition, psychokinesis
states of consciousness 2-4%
people:
william james –
sigmumd freud
ernest hilgard
dualism vs monism (mind & body)
consciousness – awareness about
ourselves and environment – diff states not on/off , states (daydreaming, dreaming, awake, hypnosis, hallucination, meditation
freud & levels – conscious, pre, un
evidence that there are levels -- mere exposure effect, priming, blind sight
levels--conscious level, nonconscious level (heart, digestion, breathing), preconscious level (not thinking about but could be/preconscious memory), subconscious level (priming & mere exposure effect), unconscious level (psychoanalytics believe in this)
sleep – one of the states of consciousness (not unconscious), circadian rhythm (24hr metobolic &thought pattern) & sleep cycle (use eeg to examine)
sleep stages
sleep onset – falling asleep
drowsy but awake – alpha waves (mild hallucinations)
stage 1 – fall asleep
1 & 2 – theta waves (high freq, low amplitude)
stage 2 – sleep spindles (short burst of rapid brain waves)
3 & 4 – delta sleep (slow wave) – deeper & less aware of environment, important for replenishing body’s chemicals, growth, & immune
go backwards thru 3 , 2, 1
rem –intense brain activity like when awake, paradoxcal sleep, dreams (but any stage), memory, rem rebound
90 minute stages 4 to 7 times /night, close to morning less time in 3 & 4, babies more rem
sleep disorders
insomnia (10%), caffeine problem
narcolepsy (suddenly fall into rem sleep)
sleep apnea – stop breathing wake up slightly and don’t know it, overweight men
night terrors – children, stage 4 sleep
sleep walking – somnambulism – kids
dreams
freud – manifest vs latent content
activation-synthesis theory – brain
intepreting what is happening physiologically during rem
information-processing theory – dealing w/daily
stress and info during rem
hypnosis
posthypnotic amnesia—forget hypnotized
events
posthypnotic suggestions
hypnotic suggestibility --
role theory – act out role
state theory – altered state of consciousness (pain control)
dissociation theory – ernest hilgard – voluntarily divided consciousness & hidden observer level monitors what is happening – hand in ice (no pain) but lift finger if any part of them felt pain
psychotherapy
drugs – psycchoactive drugs – chemicals change chemistry of brain
agonists – mimic neurotransmitters
antagonists – block neurotransmitters
reuptake inhibitors
drug dependence
tolerance – drug takes place of natural neurotransmitter
addiction
withdrawal & symptoms
stimulants (caffeine, cocaine, amphetamines,
nicotine) – speed up processes include. ans (hr, breathing), leads to euphoria (concaine), side effects – disturbed sleep, reduce appetite, anxiety, heart problems)
depressants – slow down (alcohol, barbiturates,
anxiolytics/tranquilizers/antianxiety drugs) valium, alcohol – inhibits judgement, cerebellum (motor coordination)
hallucinogens (psychodelics) – sensory
hallucinations, identity loss, vivid fantasies (lsd, peyote, mushrooms, marijuana), remain in body for weeks – add a little – more profound effect – reverse tolerance
opiates – morphine, heroin, methadone, codeine,
opium (poppy plant), agonists for endorphins – painkillers & mood elevators, drowsiness & euphoria, very addictive b/c rapid brain chemistry change
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