Sensation and perception Flashcards
sensation
refers to physical reality of signals that body picks up and transmits to nervous system
perception
how nervous system interprets sensation
sensory receptors
specialized dendrites of sensory neurons that respond to various physical stimuli by generating ap’s to the CNS
nerves
bundles of axons
ganglion
bundle of cell bodies in pns
properites of sensation that are communicated
location
modality
intensity
duration
exteroreceptors
respond to outside stimuli
interoreceptors
respond to internal stimuli
chemoreceptors of the body include
olfactary receptors and gustatory receptors
what kind of chemicals do olfactory receptors respond to
volatile
what kind of chemicals to gustatory receptors respond to
dissolved
tastes recognized by gustatory receptors
sweet, salty, sour, bitter, savory
photoreceptors
respond to specific wavelegths of electromagnetic radiation
hair cells in ears
respond to pressure signals from sound waves
- also sense rotational acceleration
endolymph
liquid of semicircular canal that moves in response to rotational acceleration and causes hair cells to move
what kind of receptors are activated by touch
mechanoreceptors
tactile corpuscles
mechanoreceptors that detect light touch
merkel nerve endings
mechanoreceptors that respond to sustained pressure
ruffini endings
mechanoreceptors that detect deep touch beneath skin surface
pacinian corpuscles
mechanoreceptors that respond to highfrequency vibrations
thermoreceptors
mechanoreceptor that responds to temperature
nocioreceptors
mechanoreceptor that detects pain
- can also be a mechanoreceptor (capsacin)
capsacin
chemical stimuli that activates nocioreceptors to detect spiciness
baroreceptors
interoreceptors that detect changes in pressure in vessels
- type of mechanoreceptor
osmoreceptors
interoreceptor detects concentrations of solutes in blood and trigger responses
propioreceptors
in muscles, tendons, joints
sense position of body in space
kinestetic sense
ability of propioreceptors to dictate where the body is in space
proximal stimulus
what the sensory receptor detects (light waves)
distal stimulus
actual object that causes proximal stimulus (tree)
absolute threshold
the minimum intensity of a stimulus that can be picked up 50% of the time, this varies between people
threshold of concious perception
the minimum intensity of a stimulus that in order to be able to consciously perceive it
priming
exposure to one stimulus influences how somone responds to the next stimulus
just noticeable difference
smallest change in magnitude of a stimulus that can be perceived as being different
difference threshold
same as jnd, least amount of change in strength that can be indicated in a stimulus
- in terms of preportions between values
psychophysical discrimination
researchers test whether research subjects can tell the difference between two stimuli and then link those findings to the actual physical properties of stimuli being tested
webers law
for any sensory input, the JND will be a constant proportion of the original input
weber’s law limitations
breaks down at extremes
- works well in range of day to day values `
webers law formula
∆I/I= K
- change in stimulus: ∆I
- original stimulus :I
- constant proportion : K
signal detection theory
method for determining a person’s ability to differentiate between presense and absense of stimuli
- goal: maximize hits and correct rejections
hit
percieving a stimulus that is actually there
miss
stimulus is there but is not perceived
false positive
stimulus is perceived but not there
correct rejection
stimulus is not there and not percieved
sensory adaptation
our senses adjust to stimuli
- reduction in sensitivity
tonic receptors
adapt slowly and send action potentials as long as a stimulus is present
example of tonic receptors
nocioreceptors and stretch receptors
phasic receptors
send quick burst of action potential and then stop
bottom-up processing
natural progression from a single piece of sensory information and assembling that into a whole perception
top-down processing
assembles individual pieces of sensory information into a picture the brain has already created
what kind of processing is this?
a chef is blindfolded and tastes a carrot, which he mistakes for a clove of garlic
bottom-up
what kind of processing is done incorrectly here?
you lose your keys in the living room and miss them sitting on the couch several times as you scan the room over
top-down
binocular cues
visual info taken in by both eyes to percieve depth
monocular cues
visual info taken in by one eye to perceieve size, perspective, orientation, brightness
gestalt theory
the whole is greater than the parts
organisms perceive entire pictures from individual parts
principle of proxomity
we percieve objects/shapes that are close to eachother as forming groups
principle of similarity
objects that are similar in some way will be perceived as belonging to a group
principle of good continuation
humans tend to percieve two objects that intersect as singular uninterupted objects
principle of closure
infer a presence of complete shapes even when they are uncomplete
principle of symmetry
interpret symmetrical objects as part of a whole rather than assymetrical objects
law of pragnaz
german for concise and meaningful
- try to find meaningful ways to represent objects that we percieve as wholes
retina
contains millions of photoreceptors (rods and cones) and converts wavelengths into action potentials
photoreceptors of retina
rods and cones
cones
perceive color and fine detail
3 different types of cones that perceive different wavelengths of light
what shortwave length of light do cones detect
420 nm, blue
medium wavelength deteted by cones
530 nm, green
longest wavelength of light detected by cones
570 nm, red
where are cones located in the retina
center aka fovea and macula (sorrounds fovea)
rod function
sense black and white light and dim-light (night vision) , do not pick up on detail well
rhodopsin
pigment and photoreceptor protein of rods that are extremely sensitive to light
where are rods in the retina
outside of center, around perimeter and responsible for peripheral vision
lens
helps focus light on retina by changing shape via accomadation
cornea
light passes through and is focused on retina
- also protects eye from injury
accommodation
ability to adjust the focus of the eye by changing shape of the lens
dark adaptation
rods take awhile to activate after being in a bright lit area
what eye structure is contiguous with the external surface of the eye
cornea
which eye structure bisects the interior of the eye into two unequal components?
lens
iris
structure infront of the lens
pupil
hole in center of iris that allows light into eye
dilatir pupillae
muscle of iris that dialates pupil to allow more light
constrictor pupillae
muscle of iris that constricts pupil and prevents light
does the sympathetic nervous system dialate or constrict pupils
dialate
ciliary muscles
adjust the shape/curvature of the lens
anterior chamber of eye
contains aqueous humor
posterior chamber of eye
contains vitreous humor
choroid
dark vascular tissue beneath the retina that contains melanin and supplies retina with blood and absorbs excess light
what is the iris continuous with
the choroid
sclera
outermost layer of the eye that is contiguous with cornea and makes whites of eye
conjunctiva
thin protective layer of epithelium that lies in front of the cornea and sclera to keep eyes lubricated
bipolar cells
neurons that rods and cones synapse on
- distinct shape with single axon and single dendrite
- first step of light being integrated
ganglion cells
cells that bipolar cells synapse on within the optic nerve
horizontal cells
between photoreceptors and bipolar cells
- mediate interaction between rods/cones and bipolar cells
amacrine cells
mediate interaction between bipolar cells and ganglion cells in optic nerve
optic chiasm
where the optic nerves intersect
nasal sides
visual field interiorly facing the nose is flipped when perceived
temporal sides
perceived on actual side, not flipped
optic tract
bundle of axons carrying visual information, runs through the laterual ventricular nucleus
superior colliculus
controls visual startle response and visual cortex
magnocellular neurons
neurons of LGN that are large
- detect motion
parvocellular neurons
neurons of LGN that are small
- pick up changes in detail
motion parallax
objects up close to us move further across our visual field than objects that are farther away
-depth
feature detection
ability to detect basic stimuli like movement and shape
parallel processing
integrate simultaneous processing
serial processing
process one stimuli at a time
- more deliberate
sound waves
longitudinal waves
hair cells
contain stereocillia that poke out into the endolympth and sway of cilia opens ion channels that trigger influx of calcium and release neurotransmitters to cells of vestibulocochlear nerve
vestibuloconclear nerve
where neural signals are transmitted and sound is transduced
where are hair cells located
inner ear within the organ of corti
outer ear
earlobe,pinna , and auricle
- funnel incoming sound waves into external auditory canal
eardrum
aka tympanic membrane
dividng point between outer and middle ear
vibrates in response to sound waves
how does intensity of sound manifest
amplitude of the sound wave (louder = higher)
middle ear function
ossicles: bones of middle ear that amplify vibrations of the tympanic membrane and eustachian tube
middle ear bones
malleus , incus, stapes
stapes
connects to oval window (boundry of middle and inner ear)
eustachian tube
valve that equalizes pressure between middle ear and environment (why ears pop on airplane)
membranous labyrinth
sub structures of inner ear
contains endolympth
perilymph
liquid between bony and membranous labrynth
cochlea
3 layered structure responsible for hearing in inner ear
- inner and outer have perilymph
- middle has endolymph / organ of corti
place theory
brain infers info about the pitch of sound based on which hair cells send signals
vestibuloconchlear nerve receives input from what (aka auditory nerve)
hair cells in the organ of corti and passes onto auditory cortex of brain
vestibular sense
hair cells also account for balance and how we orient ourselves in 3d space via semicircular canals
semicircular canals
sense rotational acceleration and stimulation of hair cells detect orientation
- arranged perpendicular to eachother
vestibule
sense linear acceleration
utricleL acceleration in x plane
saccule: detects acceleration in y plane
otoliths
earstones that stimulate hair cells
somatosensation
touch, pressure, pain, temperature, position, movment, vibration
two-point threshold
minimum distance between two stimuli on skin that can be percieved as two distinct points
denser distribution of nerves- smaller two point threshold- more sensitive
homonoculus
visual demonstration of various sensitivity of skin in different areas of body
-scale with size proportional to nerve density
physiological 0
reference point of skin that varies between indivudals
gate theory of pain
body can turn off pain signals in the spinal cord depending on overall pattern of input
taste center
in thalamus and is sent to gustatory cortex
where are smells first processed
olfactory bulb
type 1 error
false positive in signal dectection theory
