chap 5: sensation and perception Flashcards
sensation vs perception
sensation: act of using sensory system to detect environ system
perception: conscious recognition and identification of sensory system
sensory receptor nerves
specialized cells of all sensory systems that convert stimulus to neural impulses
sensory transduction
process of turning sensory stimuli to neural impulses
thresholds
point of intensity that stimulus must meet to initiate an impulse
absolute threshold
minimal stimulus needed to be detected 50% of the time, bcs weak stimulus isn’t always noticed
just noticeable difference
minimal diff b/w 2 stimuli to notice difference i.e. 2 to 4 on volume
weber’s law: JND is proportional to initial size of stimulus and not fixed across stimulus
i.e. if already loud music, need greater volume than if quiet to notice diff
signal detection theory
response to signal depends on ability to differentiate signal and noise, as well as response criteria
thresholds and sensitivity
ppl don’t have fixed sensitivity, more likely to notice difference if experienced, and has consequences
sensory adaptation
repeated stimulation of sensory cell leads to dec response
olfactory adaptation
odour not distinguished bcs prolongued exposure
bottom-up processing
environ stimuli is transduced to impulse, goes to more complex part of brain
i.e. to recognize face, light hits, goes to impulse, goes to visual pathway
top-down processing
led by cog processes like memory or expectations
i.e. allow recognition of friend’s face, expect to see them, etc.
perceptual set
readiness to interpret stimulus in certain way i.e. taste apple when bite onion
olfactory receptor neurons
cells that convert chem signals from odourants to impulse to brain
located in cilia, mucus
only certain odours attach to receptors and must reach absolute threshold
papillae
bumps on tongue w clusters of tastebuds (sensory receptor cells)
taste receptors
aka tastebuds
detect sour, salty, sweet, bitter, umami
spice is result of caspaicin, not a taste
path of smelling
signals from receptors, olfactory nerve, olfactory bulb, cerebral cortex and piriform cortex
olfactory bulb
first region where smell reaches brain, below frontal lobe
piriform cortex
recognizes odours, is changeable in adulthood and can identify smells w experience
taste pathway
info sent to thalamus and cerebral cortex, working w reward circuit to inc pleasurable taste
info goes to insula for disgust
development of taste and smell
both well-devleoped at birth, recognize and prefer mother and associated smells (prfume)
kids have more tastebuds, like sweet when babies, like sour at 7, like bitter in adulthood
ageusia
inability to taste
dysgeusia
phantom smells
hyposmia
reduced ability to smell, still have some
anosmia
inability to smell at all
reflex epilepsy
odour leads to seizure
cutaneous receptors
free nerve endings, ruffini’s end organs, paciman corpuscles, meissner’s corpusles
ruffini’s end organs
respond to heavy pressure and joint mvmnt
located deep in skin
meissner’s corpuscle
receptors to phys stimulus on lips, palms, fingertips
make to impulses
free nerve endings
receptors that make touch, pressure, pain into neural impulses
paciman’s corpuscles
located deep in skin
respond to vibration and heavy pressure
brain and touch path
free nerve endings, spinal cord, thalamus, somatosensory cortex
how is touch processed
contralaterally: info processed on opp side as receieved
slow pathway
unmyelinated, for mild burning pan
fast pathway
myelinated axons for immediate pain, fast signals
devleloping touch
important to learning and devleopment
touch enacted by you less noticeable, more noticeable if other senses involved i.e. blindfolded
gate control theory of pain
neural activity can close gate, preventing pain from travelling to brain i.e. rubbing shin to dec pain
familial dysautonomia
inability to feel pain due to genetic factors
what causes phantom limb
somatosensory cortex still active despite amputation
frequency
number of cycles of soundwaves, hertz
determines pitch of sound high/low
amplitude
height of wavelength, decibel
determines loudness of sound
cochlea
inner ear, where transduction of hearing occurs and vestibular system is
has fluid called endolymph that moves bcs of soundwaves
basilar membrane
where fluid in cochlea moves, has hair cells attached that conduct electrical signal
frequency theroy
diff sounds are converted into diff rates of action potential, and high freq sounds have more rapid firing
place theory
diffs in sound freq activates diff regions of basilar membrane
brain equates location of activity w specific freq in membrane
tympanic membrane
ear drum
ossicles
bones in ear
hammer, anvil, stirrup
maleus, incus, stapes
path of sound
cochlea, brainstem, thalamus, auditory cortex
processed as tonotopic map
development of hearing
occurs before born, can recognize mother’s voice best and music heard prenatally
conduction hearing impairment
damaged eardrum prevents soundwaves from being carried properly
damage to ossicles can’t conduct sound from eardrum to cochlea
nerve hearing impairment
damage in inner ear or auditory pathway
cochlear implants
surgically implanted to allow transuction in inner ear (signals)
has critical period before surgery less effective
cornea
transparent protective layer over eye that light passes through
pupil
small opening in eyes
lens
inner part of pupil w retina
retina
contains all receptor cells of eye, transduces light
cones vs rods
more rods than cones
cones for central vision and colour
rods for night vision and peripheral
fovea
centre of retina with only cones
optic nerve
ganglion cells that carry visual info to brain
trichromatic theory
can make all colours by mixing primary, bcs cones have 3 sensors for colour
opposite process theory
colour pairs inhibit e/o
when stare at a colour for a long time, receptors fatigue and appear in other colour
development of vision
newborn sight improves at 2 months, and is fully developed at 8 months
strabismus
eyes not aligned and don’t work together, sending diff images to brain
can lose function in one eye
ambylopia
lazy eye
loss of sight in weak eye, caused by abnormal development of visual cortex
detached retina
separates from eye, needs surgery to prevent blindness
causes floaters and blurriness
cortical blindness
result of brain damage
can have blind sight, unaware of actions but avoid obstacles
where pathway
determine location of thing
hemi-neglect: ignore one side of visual field i.e. only eat right side of plate
what pathway
determines what a thing is
visual agnosia: damaged pathway, unable to recognize objects
binocular cues
convergence-neuromuscular cues: as object comes closer, eyes move to centre
retinal disparity: brain sees diff perspectives of object
monocular cues
eleveation: seems further if on higher plane
texture gradient: more texture when close up
linear perspective: parallel lines appear to converge
relative size: if objects known to be same size look diff, bigger is closer
muller-lyer illusion: vertical lines appear longer than horizontal
vestibular system
located in semicircular canals, where fluid mvmnt says upright or not
kinesthesis
knowing body part location and position bcs of receptors in muscles
prospagnosia
face blindness, genetic or from trauma
gestalt top-down processing
proximity, if close tgt are grouped
closure, see finished unit i.e. full chair
figure ground, see background and object
similarity, similar objects are grouped
