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perception final :(


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active v. passive perception?
most is passive b/c cheaper and less dangerous, active is more powerful and less susceptible to changes in environmental conditions
external systems
long range (vision, audition), short range (gustation, olfaction, somatosensation)
internal systems
balance, proprioception (relation of organs)
5 sensations, perceive through heart b/c correlation btwn heart rate and sensation
everything is a reflex, seed of consciousness in brain
wilhelm wundt- 1879based on systematic observation-- observers catalogued elemntary mental states-- prob is language and consciousness
structuralist introspectionism
titchener--atoms of thought-- dies out by 1930s
seek exact quantitative relationships btwn physical parameters in outside world and qualities in mind of observer-- Gustav Theodor Fechner
methods of psychophysics
method of limits, method of adjustment, method of constant stimuli, magnitude estimation
method of limits
stimulus parameter presented in up or down order until subjects change answer and avg crossover valu = thershold. pros: quick, easy, need several trials, effective when approx response already known. cons: not very reliable, history dependent estimates(hysteresis), have to know approx range
method of adjustment
match test stimulus as close as poss to standard comparison stimulus-- pop in color psychophys or percep of space. pros: quickest & easiest, most fun. cons: most unreliable, set up biases ( motor interactions), requires trained observer
method of constant stimuli
stimuli presented in random order, samples more than parameter range to prevent hysteresis. pro: yields reliable theshold estimates, no hysteresis. cons: large # trials, under/oversampling stimulus ranges, fatigue & training effects
difference thresholds
compare stimulus against variable standard to find JND
webers laws
ratio btwn diff threshold and standard stimulus is usually constant-- t/s= constant (weber fraction)
manitude estimation
most percep doesnt occur at thresholds-- subject introduced to standard with magnitude and asked to rate test stimuli relative to standard
steven's power law
2 si= <2 pi (response compression) 2si=2 pi (linearity) 2 si= >2 pi (response expansion)
signal detection theory
how to make optimal decisions under conditions of uncertainty- fire alarm example ( alarm and no alarm vs. faire and no fire)
SDT type 1 and type 2 errors
1: claim theres an effect when there is none 2: don't see effect when there is one
our knowledge of world, mental reps of the world, and operations on those reps
basic, lower cog functions
perception, attention, memory, imagery (mem & image -> categorization)
higher cog functions
decision-making, reasoning/prob-solving
perception =?
all of lower & decision-making
saccadic eye mvmnts
3 times per sec, brain shuts of incoming info
efference copy
percepual stability- ex. tickling
negative feedback
feel less than you exert, feel more when your the victim
emission theory of vision
empedocles- ray from eye to object, ray from object to eye - ACTIVE
intromission theory
lucretios- sun to object, object to eye
criterion for curves with sdt
want curves with large diff in mean and narrow variance
ROC curve
receiver operating characteristic- sensitivity of system- hits on y axis & false alarms on x axis
difference btwn means of probability distributions )signal v. noise)-- want d' to be as high as possible!
functional magnetic resonance imaging--measures bloodflow to an area: active neaurons take up oxygen, more oxygenated the more coherent the spins picked up by the magnet, compare activity to baseline
imagery debate
do mental reps of images retain the depictive properties of image itself or is it language? fMRI proved in image area, not language (kosslyn)
pros if neuroimaging
noninvasive, assess relatively complex behaviors, cheap & available at universities
cons of neuroimaging:
limited to structure & dynamics of vascoclature, temporal resolution limited to 1 sec, nonlinear relationship btwn blood flow and neaural activity, measures inputs to area, not outpts (dendritic activity, not action potentials), blood flow levels can change without corresponding changes in neural activity
parietal lobe, temporal lobe, cerebellum, occipital lobe, frontal lobe
spacial, auditory/memory, motor learning, visual, language
central sulcus
everything behind is perceptual, everything in front is motor
the neuron
dendrites squiggly attached to cell body w/ nucleus inside, axon hillock/spike initiation zone between cell body and axon (myelin long parts, nodes of ranvier short parts), then at the end is the synaptic cleft
resting membrane potential
resting membrane potential is when diff between outside (more +) and inside is -70 mV. this is created by imbalance of ions (na+, na-, k+). at rest, most k is inside and most na is outside and k can get through the k channel and the k wants to be as far apart as possible.
action potential
electricity flows, na flows into axon through na channel, depolarizes to -40 mv (threshold where na channels open) spurring action potential, and the voltage spikes to + 40 mv. at +40 mv, na + channels inactivate (abs. refractory period) and k is pushed out until back to -60 mv, except k is outside and na is inside. after AP, pumps back to rp conditions
absolute refractory period
+40 mV, na + channels inactivate, completely unresponsive to second stimulus
put electrode next to neuron to pick up ion changing directly
3 interactions of wavelengths with matter
no interaction: transparent specular reflection: mirror, goes in straight, comes out straight, etc scattering: absorb some energy, change direction- normal object
lens- 2 types
converging & diverging
3 parts of eye that bend light
cornea (fixed lens that converges light), lens (if contracts, lens fatter, etc), vitreous body (gets dirty with age )
myopia/ hyperopia
eye too big, needs diverging lenses/ eye too short, need converging lenses
retina-- layers
transduces phys energy from light into electric signals-- gc, amacrine cell, bp, horizontal cell, pr, pe
rhodopsin is pigment, can detect single photon, responsibe for scotopic (night) vision, bleached at high light levels, more numerous
3 classes using 3 diff photopigments, resp. for photopic vision, only active at high light levels, peak in fovea
optic nerve
blindspot where all ganglion cell axons exit eye
signal processing in retina
photoreceptors transduce light into electricity, then connected to bipolar cells, which are connected to each other by horizontal cells, and bipolar cells are connected to ganglion cells. information transfer from bp to gc is modulated by amacrine cells
convergence in retina
125 mil receptors and 1 mil that send outputs-- degree of convergence diff for rods and cones
receptive field
part of visual field wherestimulus is effective in changing the electrical activity of a neuron
lateral inhibition -- in retina
neuron inhibits or suppresses its neighbors, for example a bright surface is represented by less spikes b/c it is redundant, so edges are more bright -- in retina, implemented by horizontal cells
parasol cell
retinal gang cells that recieve inputs from rods- are large & have large rfs
midget cells
retinal gang cells that recieve inputs from cones- are small and have small rfs
receptive fields of ganglion cells
have center and antagonistic surround- ON gang cells are activated by light in the center & suppresed by light in surround, OFF gang cells activated by light in the surround and suppresed int he center
suprachiasmatic nucleus
receives inputs from photosensitive gang cells, only few optic nerve fibers terminate here, regulates sleep- wake cycles according to the environment, sensitve to bright light for long periods of time-- causes insomnia in the blind
superior colliculus
some fibers of optic nerve terminate here, involved in control of saccadic eye mvmnts, could be involved in blindsight
subcortical structure at center of brain- signals from all sensory organs except smell pass through, connected to all brain areas through thalamo-cortical loops
possible functions of thalamus?
could be relay responsible for filtering info, could be involved in consciousness, could reformat signals for cortex
nucleus in thalamus where visual info passes through- has 6 layers which each receives input from one eye so each side retains info from one visual hemifield-- ci? ic, ic.
lgn layers 1-2
magnocellular- receive inputs from parasol gang cells
layers 3-6
parvocellular- inputs from midget gang cells
v1 function
extract fund. features- orientation, ocular dominance, spatial freq, motion, depth, color
v1 rfs
larger than lgn's and elongated, inhibitory surrounds a form of lateral inhibition
orientation turning curve
neuron has preference for certain orientation
population tuning curve
1 trial, many neurons, brain chooses for which neurons are most active
spatial frequency receptive field
if more lines fit into receptive field, higher freq
how is cortex organized?
hierarchical, computational columns-- each column does one feature, neighboring columns selective for similar features
cortical divergence
1 mil retinal gang cells-> 100-200 mil v1 neurons
how is v1 organized?
retinotopically- if neighboring in vis field, neighboring in cortex and more cortical space in v1 allotted to rep signals from fovea
specific legions in v1 cause complete loss of vis function in some regions of vis field
cortical blindness
complete loss of v1 function
2 streams of vision
dorsal (where?) vs ventral (what?)-- example of parallel, hierarchical processing in brain
ventral stream
dorsal stream
precise function unknown, responds to illusory contouts
responds to elementary shapes, curvature, geons
inferotemporal cortex- object perception
fusiform face area- face perception
medial temporal area- responds to visual motion and computes object velocity
frontal eye field- eye mvmnts, voluntary saccades & pursuit eye mvmnts
medial superior temporal area- optic flow fields using focus of expansion
lateral intra-parietal area- integration of motion percep/info over time and diff motion stimuli- decision making/categorization
what dimension lost in the retina?
3 kinds of depth cues
oculomotor, monocular, binocular
oculomotor depth cues
work at short dist, accomodation (lens) and convergence (object far away, eyes forward, object close, eyes converge)
9 monocular depth cues
occlusion, shadows, relative height, spatial freq, texture gradient, linear perspective, atmospheric perspective, familiar size, motion parallax
miller- leier illusion
2 lines that appear to be diff lengths cuz of arrows on ends
binocular vision
binocular disparity
calculate diff btwn 2 eyes to calculate depth-- disparity btwn positions of 2 image pts on retina
objects that fall on the horopter..
fall on corresponding pts on retinae and have 0 disparity
objects that fall off the horopter....
fall on noncorresponding pts on retina: farther away= uncrossed and closer= crossed
absolute disparity
angle btwn actual pt and corresponding pt- indicates how far from the horopter
relative disparity
diff btwn absolute disparities of 2 objects- indicates how far they are from each other
pulfrich effect
pendulum circles around, not side to side
the correspondence problem
to compute depth, all dots in one image must be matched up with dots in other image
motion parallax
close object moves opposite, far object moves same
where are neurons sensitive to absolute disparity and relative disparity found?
absolute found in early visual cortical areas/dorsal stream and relative in later areas/ ventral stream
motion-- fundamental or derived?
seperate perceptual dimension- present in most animals
evidence for motion as seperate perceptual dimension
motion after-effect, apparent motion (tv),induced motion (illusions)
reichardt detectors
in vi- integrate illuminance signals from lgn- direction and speed selective
motion rf orientation
orietned in space time (x=space, y=time), sensitive for direction and speed
motion camoflage
keep angle constant
aperture problem
if end of line not in sight, you can only see component perp. to orientation of line
IOC- intersection of constraints
velocity found by connecting origin of velocity-space to intersection of constraint lines--computes global motion/veridical object velocity
area STPa
biological motion--ex point light walker
most common color blindness--3 kinds
dichromats: protanopia AAO deuteranopia AOA tritanopia0AA
trichromatic theory of color
aka young-helmholtz theory--color is relative activity of 3 cone photoreceptors as activated by diff wavelengths, evidence is color deficiencies and color matching experiments--true in retina
physically diff, perceptually same
opponent process theory
evidence is color mixtures, afterimages, color contrasts-- colors oppose each other-- true in LGN
additive vs subtractive color mixing
additive- lights, add energy at diff wavelengths subtractive- paints, subtract energy
color-brightness constancy
illuminance biases amnt of wavelength reflected-- various processes involved
color in the cortex
color responsive neurons found in many vis. areas in ventral stream-- distributed process
adams surrounds
lined colored squares, one is attractive shift, one repulsive
object perception & memory
memory next door, once object identified, ou know more about it then you see and youll rememebr it forever
inverse projection problem
image on retina is ambiguous, could have been created by diff objects, infinite # soluions and brain must pick one
viewpoint invariance
can see same objects at diff perspectives
problems with object recognition
ambiguity, viewpoint, occlusion/incompleteness, image quality, lighting, unfamiliarity
psych functions underlying object perception
percep. segregation, percep grouping/organization, linecontinuation/ completion
principles of percep segregation
figure/ground--symmetry, smaller area, meaning, motion imply figure
percep grouping
see things easiest/ likeliest-- gestalt!
old and wrong percep grouping belief-- se little specks and put them all together
gestalt-- 8 principles
whole more than the sum of its parts- pragnanz (least assumptions), similarity, good continuation, connectedness, proximity, common fate, meaningfulness/familiarity, synchrony
line continuation
tendency to interpret lines as continuous- smoothest interpretation favored
recognized by v4- non-accidental, invariant features- straight edges, collinearity, t-junctions, etc
lesions in area it create.?
visual agnosias, probs with viewpt invariance and object segmentation
neural responses in area it
very specific to object, invariant to color orientation size texture
binocular rivalry
if you see diff stimuli in 2 eyes then brain represses 1
3 possibilities for how objects represented in area it
grandmother neurons- one neuron, one stmulus, logical conclusion of hierarchical model but doubted population code- decode peak along linear stimulus dimension- conventional barcode- key combo of activities, if true then were out of luck
plasticity & 3 time scales
central to cog function, think hapens on level of indiv neurons-- ontogenetic (dev), short term ( percep learning), ultra short term (attention, adaptaton)
unilateral parietal lesion
hemi-neglect- breakdown in spatial attention ( draw half a clock)
attention & 2 models
results from narrowing cortical architecture of less & less independent info channels (bottleneck)-- biased competition and feature similarity gain
biased competition
neuronal pool with diff tuning prefs inhibit each other and compete for higher firing rate, one has head start b/c attention
feature similarity gain
no change in fund tuning props or prefs, attention changes gain of pool-- attention and phys characteristics direct tradeoff-- evidence supports!
decision making in vis cortex
once neurons in lip reach certain threshhold, decision made
cortex columnar structure
neurons organized in cortical columns w/ similar prefs grouped together, columns compete, neural voting isnot equal but weighted by reliability
corollary discharge theory
prob- motion could be self or other generated, so motor areas send efference copies to percep areas
ebbinghaus illusion
brain takes context into account, but motor areas make up for it
time perception
might not be percep b/c no transformation of energy involved, could be what brain does anyway, interpreted.. not simple readout from pacemaker
4 modes of temporal cognition
simultaniety, temporal order, subjective present, duration
subjective present
3 seconds, evidence, necker cube changes every 3 secs, seach though in speech should be 3 secs, like saddle in time, 'indifference interval'- at 3 secs your subjective estimate of time matches objective experience
duration percep
prone to ext & int influences, changes with diff time scales, practice effects
physiological clock hypthesis
chemical? pacemaker of some sort, ev. temp (fever, ppl count faster), fatigue (when tired, count longer), drugs (anesthesia shortens time, drugs lenthen it)
cognitive clock
60s and 70s-- percep is interpretation of dynamics of mental content going on anyways, more like byproduct
time percep as change percep
if more events occur, interval judged as longer, if even is novel, interval judged as longer, if events are complex, interval judged as longer --distinguishes empty from filled
attention effects on time percep
if paying attention to passage of time, time lengthens dramatically
memory effects on time percep
in hindsight, filled intervals appear longer and empty intervals shorten
emotions effects on time percep
pain & fear drastically lengthen time, positive emotions shorten it
age & passage of time
passage of time accelerates with age-- gives rise to logtime hypothesis-- new time interval judged relative to time passed thus far, ex. 1 yr old, next year is 100% time already spent-- bad implications for subjective life expectancy!
alternate explanantions for slowing time passage with age
limited space for memory representatons, slowing metablism, lodified log hypothesis
possibilites for physiological/neuronal time percep
completely distributed (neuronal fires, refractory periods, etc), suprachiasmatic nucleus, cerebellum (process reg, precise, short timesclases like motor actions), parietal lobe (moderate timescales, gauge elasped time)
function of temporal cognition on short and long time scales
short- organize behavior as coherent goal-directed set long- organize behavior in terms of behavioral economics
the auditory system & stimulus
long-range, external, stimulus is pressure waves in air(20-20000 Hz in humans)
pure tone
sounds represented by a sine wave
1/wavelength-- higher freq= higher pitch
corresponds to sound pressure, measured in decibel
function of bouth frequency and amplitude
where is our hearing most sensitive?
300-5000 hz- conversational speech
complex sounds
many diff freq present at once, most sounds, additive synthesis (pressure waves add)
music notes
fundamental freqs added with other tones-- harmonics
fourier frequency spectrum
simple sine wave components of soundwave
produced by harmonics
frequency in vis and auditory systems
vis: hue, color aud: pitch
amplitude in vis and auditory sstems
vis: luminance aud: loudness
white light and white noise
contain all frequencies
outer ear
acts as funnel to direct sound waves towards inner structures- filled with air
middle ear
3 small bones (ossicles) that amplify sounds--filed with air
inner ear
contains structures that transduce sounds-- filled with liquid
sound waves in middle-> inner ear
make eardrum vibrate, hammer/anvil/stirrup take mass of vibrations and transfer to oval window for amplification
like funnel
equalizer system-- amplify specific freq more thanothers (ex. conversation)-- startwearing out with age
organ of corti
contains transducers to transduce mech. pressure waves into action potentials--contains basilar and tectorial membranes and hair cells, hair cells cilia move against tectorial
tonotopically organized--freqs map onrderly on length
basilar membrane
has hair cells, death starts near beginning closer to oval window,pattern of vibration of hair cells depends on freq of sound wave
place code
pattern of vibration of hair cells depends on freq of sound wave-- high freq near oval window,, low freq near apex, stiffer at base and looser at apex
place theory
each freq causes maximum displacement of basilar membrane at diff position
mechanical gating
vibrations mechanically open channels of cilia, changing voltage inside cell--vibes pull open ion channels, ions flow in, voltage potential changed in cell, changes amnt of neurotransmitter released into synapseof neuron in auditory nerve
auditory pathway to cortex
ear, auditory nerve, cochlear nucleus (brain stem), superior olivarynuclei (sound localization, crossing over info from both ears in both hemispheres), inferior colliculus (reorients attention to sound), medial geniculate nucleus, primary auditory cortex (a1, temporal lobe)
3 parts of auditory cortex
core are ( pure tones) belt area (higher order sounds, lyrics, speech) primary auditory cortex (organized tonotopically, speech freq overrepresented
auditory adaptation
cells in cortex have characteristic freq, prolonged exposure to tone of cf raises threshold of neuron -- why stop hearing ambient noise
localizing sound sources- where stream
3 ways- interaural time diff, interaural level diff, spectral cues
interaural time difference
encode sound sources-- diff in time it takes for sound waves from single source to reach r and l ear, neurons in superior olivary respond to itds, work like reichardt detectors
interaural level difference
encode sound localization-- diff in spl at each ear, ear away casts acoustic shadow, slightly quieter. mostly for high freq sounds
spectral cues
encode sound localization-- monaural, head related transfer function, ear amplifies some freqs and attenuates others, effect depends of vertical position of sound source to head
identifying sound sources
cochlea responds to simultaneous sounds from mult sources undifferentiated, stimuli must be grouped to be identified
shepards tones
in octave relationship to each other, always in equal loudness
major diff btwn vision and audition
temporal fidelity in audition better than vision b/c vision is chemical transduction, not mechanical
mcgurk effect
auditory ba, visual ga, brain guesses da
sound induced rabbot effect
think as many rabbits as there are sounds
motions bounce illusion
sound makes it unambiguous
subcortical processing-- cutaneous senses (touch, temp, pain), proprioception (acceleration/body orientation), kinesthesis (position/mvmnt of limbs), introception (thirst, satiety, nausea, bladder, etc)
'retina' of cutaneous senses b/c transducers, 3 layers - epidermis, dermis, subcutaneous)
4 touch receptor types
merkel receptor/merkel disk, ruffini cylinder/ ending, meisner corpuscle "stack", pacinian corpuscle "onion"
merkel receptor
touch receptor-- shallow, small rf, slow adapting, respond to slow pushing and fine details
ruffini cylinder
touch receptor-- deep, large rf, slow adapting, respond to sloow stretching
meisner corpuscle
touch receptor-- "stack", shallow, small rf, rapid adapting, responds to light tapping, flutter, gripping things
pacinian corpuscle
touch receptor-- "onion", deep, large rf, rapid adapting, respond to vibration, texture from motion
2 pt threshold
used to elicit absolute sensitivity of diff regions of skin to infer spacing/size of rfs, thresh lowest on face and hands, hairy skin less sensitive than hairless skin
2 ascending pathways for touch
- touch fibers enter spinal cord in dorsal root, some fibers synaps onto local interneaurons which synapse onto motor neurons (spinal reflex arc) -travel up to brain carrying info to brain stem, travels in medial lemniscal pathway, synapses in brainstem and cross to opposite side of brain, synapse in thalamus and neurons project to cortical areas
free nerve endings, cold fibers react to decrease in temp(20-45 c) and warm fibers react to increase (30-48 c), indiv fiber has preferred temp
spinothalamic tract
in spinal cord- conveys temp and pain related signals to brain
somatosensory cortex
s1 & s2-- immediately poterior to central sulcus, full sensory map of body, organized somatotopically (size scaled with amnt of sensory input)
use dependent cortical magnification
more you use things, more area they get
focal hand dystonia
musicians--crippling pain in hnds from overuse and repetition, therapy by immobilizing all fingers but one, get back one at a time
phantom limb pain
more than half of amputees, usually when amputated later in life, prob sprouting with representations of other regions invading lost limb area
insular cortex
homeostasis, thirst hunger nausea, emotions, seems to represent trust (link btwn physical and interpersonal warmth)
3 kinds of pain
neuropathic-results from damage to neural system itself nociceptive- activation of receptors (nociceptors) in skin inflammatory- due to tissue damage, release chemicals that activate nociceptors
visceral pain
organs that are in contact with outside wold have inflammatory pain (digestive system)
pain receptors- specialized for diff stimuli, free nerve endings connected to various fibers
A8 free nerve endings, C free nerve endings
a8- small, myelinated, high conductance speed, sensitive to mechanical noxious stimuli c- small, unmyelinated, slow conductance, sensitive to noxious stimuli
cortical pain processing
many regions involved, sensory aspects in somatosensory cortex, emotional distress processed in anterior cingulate cortex (active in sadness, unpleasantness, pain, social pain)
3 types of pain control
peripheral- gate control theory, pain intensity top down influenced by many factors central- endogenous opiates and corresponding receptors in brain conscious- pain control through neurofeedback (fire)
chemical senses
olfaction and gustation, short range, most ancient system available to organisms, detects presence of certain molecules in environment
macrosomatic/ microsomatic animals
macro- high reliance on olfaction micro- low reliance on olfaction
smell prism
(from top to bottom, l to r) flowers, spicy, fruity, resinous, putrid, burned
olfactory system
olfactory mucosa->olfactory bulb->pyriform cortex, orbitofrontal cortex, amygdala NO THALAMUS
entosomatic state
cribriform plate cuts receptor cells and cant smell, often leads to depression b/c smell stimulates brain
nasal passage
-> olfactory receptor cells, go through cribriform plate holes to olfactory bulb
olfactory receptor neurons
analogous to rods/cones, mouse has more types than we do (350 for humans), 10,000 of each type, membrane bound proteins located in cilia on top of ORN causes change of membrane potential
odor perception in relation to phys/chem properties
similar molecular structure doesnt lead to similar perception, combinational
olfactory bulb organization
4 zones, contains glomenulus (primary structure in bulb, receives input from 5000-10000 ORN, input is chemotopic) and mitral cells which fire action potentials-- ipsilateral (no crossing over)
neurons in olfactory bulb
many respond to variety of odorants, many multimodal, affected by behavioral/emotional context
chemicals that elicit behavioral response, animals have accessory olfactory system (vomeronasal organ), evidence for human pheremones in syncing of periods
major histocompatibility complex
females prefer odors from males with allelic matches to paternally inherited MHC genes
taste vs flavor
taste is gustatory system, flavor is taste and olfaction
gustation organ, not dedicated cuz also somatosensory, covered with papillae
papillae & 4 types
about 6 taste buds in each-- filiform (conical, entire surface, not involved in taste), fungiform (mushroom, tip &sides), foliate (folds along sides), circumvaliate (flat mounds, back)
taste buds
6 in each papillae, also in roof of mouth and gut, sweet salty sour bitter umami (all over tongue,not specific places)
gut taste receptors
carbs, fat, protein, etc b/c tongue taste receptors too small to fit
gustation pathway
3 facial nerves->NST->thalamus->insula or frontal operculum
flavor perception
oral &nasal cavities linked in nasal pharynx, thing on tongue evaporates to nasal covity, phys processes operating outside percep pathways have influence on flavor

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