Sensation & Perception Chapter 4 Flashcards
Sensory branding
esciting ads on drab product ie Tide Detergent
Sensation
simple stimulation of the sense organs - body reacting to physical world
Perception
organization & identification - interpretation of a sensation in order to form a mental representation ie light info to words - not reading directly - sensation → perception
Fechner sensation-stimulus mathematical relationship
1801-1887 “In order that the intensity of a sensation may increase in arithmetical progression - the stimulus must increase in geometrical progression.”
Vision sensory input
light reflected from surfaces - info about shape/colour/position
Audition
vibration cause Δ air pressure - move through space towards the ear
Touch
pressure of surface against the skin - shape/texture/temp
Taste and smell
molecules in air/saliva - what we do/dont want to eat
Structuralist approach to senses
Wundt & Titchener - introspection to measure perceptual experiences
Psychophysics + typical experiment
methods that measure strenght of stimulus + observerer’s sensitivity - ie yes/no response - then compared against measure
Absolute threshold
the minimal intensity to just barely detec stimulus in 50% of trials - states in question: sensing/not sensing - gradual change between them ie curve
Just noticeable difference
JND aka difference threshold - minimal change in a stimulus that can just barely be detected - NOT fixed quantity - needs standard - ie bright standard - harder to detect change
Weber’s law + example
the JND of stimulus = a constant proportion despite variations in intensity - ie 1 oz → 2 oz noticeable vs 20oz → 21oz not
Absolute thresholds vision
vision - a candle flame at 50 kilometres on a clear night
Absolute threshold hearing
tick of a watch at 6 metres(20 feet) in a quiet room
Abs threshold taste
one teaspoon of sugar in two gallons of water
Abs threshold smell
1 drop of perfume in a 3 room apartment
Abs threshold touch
the wing of a bee falling on your cheek from 1 centimetre
Is signal detection gradual
YES - all or none change in brain unlikely - ABS thresh is only perceiving 50% of time
noise
other stimuli from environment that interfere with signal detection
signal detection theory
response to stimulus depends of Person sensitivity in presence of noise & on decision criterion - yes=hit - theory allows quantify a response when noise present
signal detection experiment outcomes
hits/ misses/ false alarm/ correct rejection
Signal detection theory proposes a way to measure this
perceptual sensitivity - cuz takes into account resposne tendencies ie liberal yesses
signal detection theory applications
- Tolbert 2006: - Signal detection theory and the diagnosis of learning disabilities 2. radiologist liberally diagnoses breast cancer
explain cons of multitasking
selective attention — only perceive what’s currently relevant — texting + driving is same effect as drink/drive — hands free doesn’t help
sensory adaptation def + example
sensitivity to prolonged stimulation declines over time as adapt to current condition is blinding light in morning then better
Sensory adaptation big idea
our sensory systems respond to changes in stim rather than constant stimulation
20/20 definition
vision of normal sharpness — associated with Snellen chart — owls have better @ 20/2
visual acuity
the ability to see fine detail
wavelengths
distance between the wave peaks — light waves vary in amp & wavelength
the 3 properties of light
1 length — determines hue 2 amplitude—determines brightness 3 purity—determines saturation
cornea
transparent — bends the light wave and sends it through the pupil
pupil
hole in the coloured part of the eye
iris
coloured—translucent— circular muscle — controls size of pupil= how much light can enter eye
lens
thickness adjusts to focus light on the retina — flatter far way rounder nearby
what is the retina/how does the image appear on it
light sensitive tissue lining the back of the eyeball — image appears upside down and backwards
fovea
area of the retina where vision is clearest — no rods
retinal surface
has light sensitive receptor cells - excited or inhibited by spots of lights — go to optic nerve
optic nerve
bundled axons to the brain
blind spot
a location in the visual field that produces no sensation on the retina
accomodation
the process by which the eye maintains a clear image in the retina
presbyopia
lens cant change shape - lens hard - so image
myopia
when eyeball is too long- images in front of retina
hyperopia
eyeball is too short — farsightedness
Photoreceptors cells
light—sensitive pigments that transduce light into neural impulses
Cones 6/7 million
detect colour - operate under normal daylight conditions - allow us to focus on fine detail - packed in fovea - so peripheral vision isn’t as clear
— Rods
120 million -active under lowlight for night vision - greys
- layers of retina cells
1 photoreceptor cells innermost 2 transparent outer layer = bipolar cells - rod cone signals to to *retinal ganglion cells - send to brain - outermost (behind eyes)
- duplex theory of vision
dark adaptation & increased sensitivity to light following period of darkness
- receptive fields
area of retina that contains rods/cones which when stimulated affects firing of specific cells in visual cortex
- centre/surround arrangement (eyes)
stimulation at centre increases cell firing whereas stimulation off-centre inhibits cell firing
— Sir Isaac Newton
pointed out colour is not something “in” light
— Visible spectrum
rainbow of hues and their accompanying wavelengths
— 3 types of cones
red long// green medium // blue short = the primary colours of light
— Lighting with primary colours
res green blue looks white in stage
- Subtractive/ additive colour mixing
Subtractive Colour Mixing - removal of wavelengths of light //Additive Colour Mixing - addition of wavelengths of light
- trichromatic theory
Young-Helmholtz -three different types of colour receptors in the retina each sensitive to a specific colour (viz.- red- green- blue)
- Shortcomings of trichromatic theory
colours dont appear to be mixtures- colour contrast effects- colour after images
- Opponent process theory
Herring- 1878 -colour perceived in three channels - 3 channels (red vs green// yellow vs blue// black vs white) - each channel members are antagonists aka dual process theory
- three perception types
beer study - see pic
— Reading out cones
read out wavelength by working backwards from relative firing rates of the 3 cones
— Colour deficiency/colour blindness
cant distinguish full colour cuz missing one cone
— what causes Colour afterimage
staring at one image too long - fatigues that cone others take over
— Colour—opponent system
pairs of visual neurons work in opposition ie red against green & blue against yellow
- lateral geniticulate nucleus
optic nerve goes to here (@ thalamus) - in right/left brain
- lateral antagonism
occurs when neural activity in a cell opposes activity in surrounding cells - Hermann Grid - see dots in periphery - fovea at center of the grid
- what does area V1 do?
- edge encoding - ie bars- some neurons fire vertical- others when 45 perceived
- the 2 visual streams
ventral- dorsal - project from the occipatal cortex to visaul areas more forward in brain - ventral/dorsal functionally distinct as shown by agnosia tests
- where does the ventral stream go
from occipatal to teporal @ front
- where does the dorsal stream go/ what does the dorsal stream do
upwards to parietal lobe - perceive spatial relations this way
- visual form agnosia
inability to recognize objects by sight - memory of objects not affected
- example of visual agnosia
cannot recognizeobjects by sight but could guide objects normally
- feature detectors
neurons that respond selectively to specific features of complex stimuli – Hubel & Wiessel discover
- binding problem
tryna figure out how features are linked together so that we see unified objects rathan than free-floating/misconnected gook
- illusory conjunction
a perceptual mistake where features from multiple objects are incorrectly combined - Treisman/Schmidt showed its not just guessing - you ight not see black letters at ends- might mix up coloured ones
- feature integration theory
focussed attention is not required to detect features of stimulus ie colour- required to bind them togeth though - full attention = better results
- parietal lobe damage
cant perform visual feature binding of feature integration theory
- modular view
specialized brain areas detect ie faces/body parts
who came up with the geon theory
Biederman
- distributed presentation view
alternative to modular view - activity across brain for each object obbserved
- perceptual constancy
even as aspects of sensory signals change- percption remains consistent
- List Perceptual Grouping rules
simplicity/ closure/ continuity/ similarity/ proximity/ common fate
- grouping
seperating an object from its surroundings - figure & background
- edge assignment
which region does that edge belong to?
- Rubin
rubin vase - the face vase illusion - figure ground relationship - when seeing face face-selective region of temporal lobe activated
- image-based object recognition
object stored in template- mental representation that can be directly compared to a viewed shape in the retinal image - ie need a template for cups/cups upside down
- parts - based object recognition
brain deconstructs object into geons
- monocular depth cues - accomodation
aspects of a scene that show depth info when viewed with only one eye
- list monocular depth cues
relative size/ familiar size/ linear perspective/ txture gradient/ interposition/ relative height in image
- binocular cues
ie retinal disparity looking straight on at book
- list Pictorial depth cues
interposition/ texture gradient/ linear perspective/ aerial haze/ shadow and light/ object familiarity and size
- illusions
errors of perception/ memory/ judgement - Mueller-Lyer - Ponzo - explanation: misapplied size constancy - Gregory 1963
- Ames room
trapezoidal but looks square from monocular viewing port - person in right appears larger
- how motion perception works
stimulates one location on retina - then another as it moves across - MT in dorsal stream perceives - brain subtracts head mvmts
- waterfall illusion
like color aftereffects - stare too long water looks like going up
- apparent motion
perception of mvmt as a result of alternating signals in rapid succession in different locations ie 24 fps film
- change blindness + door example
when people fail to detect visual changes in scene ie direction giver doesnt notic asker swapped with another guy behind door
- inattentional blindness + gorilla example + cells
failure to perceive objects that are not the focus of attention ie wont see gorilla when watching game/ cell phone distraction
- sound waves
changes in air pressure unfolding over time
- pure tone
ie from a tuning fork - increases air pressure and then creates a relative vacuum
- Frequency
wavelength - determines pitch
- Amplitude
loudness - a sound’s intensity
- Complexity
timbre - a listener’s experience of sound quality/resonance
- forms of transduction
light - electromagnetic radiation vs sound - physical change in qir pressure so we need different forms of transduction
- outer ear to inner ear
Pinna to oval window to cochlea (e)
- outer ear
collects sound waves and funnels to middle ear
- middle ear
ossicles - transmits vibrations to cochlea
- inner ear
cochlea (its rolled up) - basilar membrane transduced into neural impulses
- cochlea
a fluid filled tube that is the organ of auditory transduction
- basilar membrane
undulates when vibrations from the ossicles reach the cochlear fluid
- hair cells
specialized auditory receptor neurons in basilar membranes
- Area A1
a portion of the temporal lobe that contains the primary auditory cortex - left hemi=language // right hemi = music
- place code (place theory e)
different frequencies stimulate neural signals at specific places on the basilar membrane
- Helmholtz 1863 – von Bekesy 1957
Bekesy observed cadaver basilar membrane with mic
- explain where on basilar membrane for high/low pitch
low= @ apex - floppy tip // high = @ base - narrow stiff end - axons fire better in hair cells of BM that move the most
- temporal code
registers low frequencies via the firing rate of action potentials entering the auditory nerve - supplements place code (Frequency Theory e) ie boom boom of bass
- Rutherford- 1886
volley theory - neurons respoond to sound by firing action potentials slightly out of place of one another
- Reconciliation of place/volley/frequency theories
20-1000 hz frequency/volley theory // 1000-5000hz volley & place coding // over 5000hz place coding
- explain localized sound sources
right/left ear stereo & hearing something in one ear before the otehr can denote farther away - turning head to sound helps hear it
- conductive hearing loss
eardrum/ossicles damaged - can’t conduct sound to the cochlea - surgery corrects
- sensoineural hearing loss
from age - damge to cochlea/ hair cells/ auditory nerve
- cochlear implant
- cochlear implant replaces hair cells so it helps sensoineural hearing loss
- somatosenses
body senses ie haptic perception - touching/grasping
- touch receptors
4 types for pressure/ texture/pattern/ thermoreceptors
- 3 principles neural rep. of body’s surface
1 left body in right brain 2 more of tactile brain devoted to areas of high touch resolution 3 what pathway upper parietal & where pathway lower parietal - fMRI evidence
- why do we feel pain
we would ignore infection// broken bone// serious burns
- tissue damage + receptors
transduced by pain receptors - A delta fibers initial pain // C fibers - longer dull pain
- the 2 pathways of pain
1 to somatosensory cortex 2 to hypothalamus/amygdala - emotional & motivation centers
- referred pain + heart attack example
sensory info from internal/external areas converges to same nerve cells in spinal cord ie left arm pain @ heart attack
- ethnic pain differences
one study said African Americans have lower pain tolerance
- gate control theory
signals from pain receptors get to spinal cord and can then be stopped (gated) by interneurons - feedback from two directions
- bottum/top
with pain also but here overall perception - bottom-up (ie feature integration theory (pop out) - Tresiman 1986) and top-down (ie misheard song lyrics e)
- explain Body Position/ Mvmt/ Balance
depend on stimulation produced within our bodies - muscles say position in space // balance from inner ear
- olfaction + gustation
olfaction smell - gustation taste - from inhaling / saliva = flavor
- explain smell
olfaction only sense connected to the forebrain - a sense for the familiar - odorant molecules
- ORNs
olfactory receptor neurons - 10 million located @ olfactory epithelium - dogs have 100x more - send action potentials into olfactory nerve
- olfactory bulb
brain structure above nasal cavity - beneath frontal lobes
- odor perception
350 ORNS in humans = 10K odorants
- object-centered approach
info about identity of odor object accessed from memory - triggers emotional response
- valence-centered approach
emotional response comes first - provids basis to identify odor
- sensory adaption in smell
smell fades so new smells can be accessed
- pheromones
biochemical odorants emitted by other members of same species - affect behaviour ie infant knows smell of mother’s breast ie gay men respond to female pheromes more strongly
- anterior insula
brain’s taste system
- why taste
to identify poisonous/lethal substances
- papillae + taste buds
papilla = bumps on tongue & each has hundreds of taste buds = organ of taste transduction
- how many buds in mouth?
5K-10K on mouth// tongue & upper throat
- taste perception + categories
perception fades with age - 5 categories - salty/ sweet/ bitter/sour/ umami (meat savory)
- inside taste bud
microvilli reactant with food tastant molecules ie sour receptor cells
- taste + smell
they collaborate
- tasters// non-tasters// supertasters
25% supertasters - they are fussy about greens/fats - nontasters develop later in life - supertasters thinner
- Hallucinations
Charles Bonnet Syndrome - primary visual cortex
- list Gestalt principles of holistic perception
proximity // similarity// closure//continuity//Pregnanz//common movement groups
- explain proximity
- elements that are close to one another tend to be grouped together
- explain similarity
- elements that are similar tend to be grouped together
- explain closure
- tend to supply missing elements to close or complete a figure
- explain continuity
- tend to supply missing elements to close or complete a figure
- explain Pregnanz
“good form” - tend to organize elements simplest way possible
Nazi symbol dorms example of what gestalt priciple
Closure
