concept 6a Flashcards
sensation
transduction of physical stimuli into neurological signals
performed by receptors in the peripheral nervous system which forward stimuli to central nervous system
transduction
the conversion of physical, electromagnetic, auditory, and other info from our internal and external environment to electrical signals in the nervous system
perception
processing of this information to make sense of its significance
helps us make sense of the world
sensory receptors
neurons that respond to stimuli and trigger electrical signals
encode multiple aspects of a stimulus
differ from one sense to another
common sensory receptors
photoreceptors hair cells nociceptors thermoreceptors osmoreceptors olfactory receptors taste receptors
photoreceptors
respond to electromagnetic waves in the visible spectrum (sight)
hair cells
respond to movement of fluid in the inner ear structures
hearing, rotational and linear acceleration
nociceptors
respond to painful or noxious stimuli
somatosensation
sense pain
thermoreceptors
respond to change in temperature
somatosensation
osmoreceptors
respond to the osmolarity of the blood
water homeostasis
olfactory receptors
respond to volatile compounds
smell
taste receptors
respond to dissolved compounds
taste
ganglion
collection of neuron cell bodies found outside the central nervous system
receive the stimulus and transmit the data to the central nervous system
projection areas
areas in the brain that further analyze the information from the ganglia
once transduction occurs the electrochemical energy is sent to projection areas by neural pathways
threshold
the minimum amount of a stimulus that renders a difference in perception
3 types: absolute threshold, threshold of conscious perception, and the difference threshold
absolute threshold
the minimum of stimulus energy that is needed to activate a sensory system
threshold of sensation
determines if the sensation is enough to be converted into action potentials
*minimum intensity at which a stimulus will be transduced
threshold of conscious perception
subliminal perception (limina means threshold) perception of a stimulus below a given threshold stimulus arrives at the central nervous system but does not reach he higher-order brain regions that control attention and consciousness
difference threshold
just-noticeable difference (jnd)
minimum difference in magnitude b/w 2 stimuli before one can perceive this difference
if the difference b/w stimuli is small then they will be perceived as the same
Weber’s law
states that there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus
(change needed/original stimulus) gives percent of jnd
signal detection theory
focuses on the changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context
perception can be affected by non sensory factors, such as experiences (memory), motives, and expectations
response bias
refers to the tendency of subjects to systematically respond to a stimulus in a particular way due to non sensory factors
signal detection experiments
consists of many trials where a stimulus may or may not be presented
trials when signal is presented are called catch trials
when signal is not presented called noise trials
after each
subjects asked to indicated whether or not signals was given
leads to 4 different results
results of signal detection experiments
hits: subject correctly perceives the signal
misses: subject fails to perceive a given signal
false alarms: subject seems to perceive a signal when none was given
correct negatives: subject correctly identifies that no signal was given
proportion of misses and false alarms indicate response bias
adaptation
decrease in stimulus perception after a long duration of exposure
detection of a stimulus can change over time
have both a physiological (sensory) component and a psychological (perceptual) component
sclera
thick structural layer covering exposed portion of the eye
white of the eye
doesn’t cover the front of the eye
choroidal vessels
complex intermingling of blood vessels b/w the sclera and the retina
along with the retinal vessels
both sets of vessels supply eye with nutrients
retina
innermost layer of the eye
contains photoreceptors that transduce light into electrical information the brain can process
like a screen consisting of neural elements and blood vessels
cornea
clear, domelike window in the front of the eye
gathers and focuses incoming light
anterior chamber
lies behind the cornea in front of the iris
posterior chamber
between the iris and the lens
contains aqueous humor
iris
colored part of eye composed of 2 muscles: the dilator pupillae and the constrictor pupillae continuous with the ciliary body iris contracts--> enlarge pupil iris relaxes--> constricts pupil
dilator pupillae
opens the pupil under sympathetic stimulation
constrictor pupillae
constricts the pupil under parasympathetic stimulation
ciliary body
produces aqueous humor that bathes the front part of the eye before draining into the canal of Schlemm
lens
lies behind the iris
helps control the refraction of incoming light
connected to suspensory ligaments
suspensory ligaments
connected to the lens
when the ciliary muscle contracts it pulls on the ligaments and changes the shape of the lens
accommodation
the change shape of the lens from the suspensory ligaments and the ciliary body
vitreous humor
transparent gel that supports the retina
lies behind the lens
duplicity theory of vision
states that the retina consists of 2 kinds of photoreceptors:
those specialized for light and dark detection
those specialized for color detection
cones
photoreceptors used for color vision
sense fine details
6 million in the retina
most effective in bright light and comes in 3 forms: short or blue, medium or green, long or red
rods
photoreceptors used for light and dark vision contain small pigments called rhodopsin low sensitivity to detail permit light vision 120 million in the retina
fovea
central section of the retina (macula)
contains only cones
bipolar cells
connects rods and cones
highlight gradients b/w adjacent rods and cones
ganglion cells
synapse with bipolar cells
group together to form the optic nerve
amacrine and horizontal cells
receive input from multiple retinal cells in the same area before the information is passed on to ganglion cells
accentuate slight difference b/w the visual info in each bipolar cell
important for edge detection
visual pathway
right visual field goes to left hemisphere
left visual field goes to right hemisphere
through the optic nerve to the optic chiasm to the optic tract
information goes to several different places in the brain: the lateral geniculate nucleus (LGN), visual cortex, and the superior colliculus
processing areas
lateral geniculate nucleus (LGN) in the thalamus
visual cortex in the occipital lobe
superior colliculus, which controls some responses to visual stimuli and reflexive eye movements
parallel processing
ability to simultaneously analyze and combine information regarding color, shape, and motion
then they can be compared to our memories to determine what is being viewed
parvocellular cells
detects shape
have high color spatial resolution
work with stationary or slow-moving objects so they have low temporal resolution
magnocellular cells
detect motion
high temporal resolution
low spatial resolution
provide blurry but moving images
pinna
or auricle
where sound wave first reaches cartilaginous outside of ear
channel sound waves not the external auditory canal which directs sound to the tympanic membrane
tympanic membrane
eardrum
membrane vibrates in phase with the incoming sound
frequency of wave determines pitch
intensity corresponds to amplitude of vibration
divides the outer ear and the middle ear
ossicles
housed in the inner ear
3 smallest bones in the body
help transmit and amplify the vibrations from the tympanic membrane
middle ear
malleus (hammer) affixed to the tympanic membrane, and acts on the incus (anvil), which in turn acts on the stapes (stirrup)
the base plate of the stapes rests in the oval window
Eustachian tube
connects the middle ear to the nasal cavity
helps equalize pressure b/w the middle ear and the environment
inner ear
sits within a bony labyrinth
contains the cochlea, vestibule, and semicircular canals
all continuous with each other and form the membranous labyrinth filled with endolymph
also contains perilymph that transmits vibrations and cushions the inner ear structure
cochlea
spiral-shaped organ divided into 3 parts called scalae that run the entire length of the cochlea
middle scala houses organ of corti and contains endolymph
other 2 scalae filled with perilymph
organ of corti
actual hearing apparatus
housed in the middle scala
lies on a thin, flexible membrane called the basilar membrane
composed of thousands of hair cells that are bathed in endolymph
on top is immobile membrane called tectorial membrane
round window
membrane covered hole in the cochlea
permits perilymph to actually move within the cochlea
vestibule
portion of the bony labyrinth the contains the utricle and saccule
sensitive to linear acceleration
part of balancing apparatus
semicircular canals
sensitive to rotational acceleration (x,y, and z planes)
arranged perpendicularly to each other
ends in a swelling called an ampulla, where hair cells are located
auditory pathways
most info passes through the vestibulocochlear nerve to the brainstem
auditory input –> middle ear–> cochlea–> auditory nerve–> superior olive–> inferior colliculus (thalamus)–> medial geniculate nucleus–> temporal cortex
tonotopically organized
the cochlea is organized this way
when the hair cells vibrate it gives the brain an indication of the pitch of the sound
smell
considered a chemical sense
respond to the incoming chemicals from the outside word via olfactory chemoreceptors
olfactory chemoreceptors
olfactory nerves
located in olfactory epithelium in the upper part of the nasal cavity
chemical signals bind to these receptors to cause a signal
olfactory pathway
chemicals bind to the olfactory receptors in the olfactory epithelium
signal sent to the olfactory bulb
then sent to higher regions of the brain
pheromeones
smell that carries interpersonal information
bind to olfactory receptors
play a role in animals social, foraging, and sexual behavior
5 basic tastes
sweet sour salty bitter umami (savory)
taste chemoreceptors
detect taste
can sense dissolved compounds (salts) and specific molecules binding to receptors
receptors are groups of cells called taste buds
papillae
little bumps found on the tongue
this is where taste buds are found
taste pathway
chemoreceptors on tongue (taste buds on papillae) detect taste
sent to the brain stem
ascend to the taste centers in the thalamus before traveling to higher brain regions
somatosensation
the sense of touch
complex
has many different receptors
4 sensations of touch
pressure
vibration
temperature
pain
5 receptors
Pacinian corpuscles Meissner corpuscles Merkle discs Ruffini endings Free nerve endings
Pacinian corpuscles
respond to deep pressure and vibration
Meissner corpuscles
respond to light touch
Merkle discs
respond to deep pressure and texture
Ruffini endings
respond to stretch
Free nerve endings
respond to pain and temperature
somatosensation pathway
transduction occurs in the receptors
then sent to the central nervous system and eventually to the somatosensory cortex in the parietal lobe
two-point threshold
minimum distance necessary between 2 points of stimulation on the skin such that the 2 points will be felt as 2 different stimuli
size of threshold depends on the density of nerves in the particular area of skin being tested
physiological zero
how temperature is judged
the normal temperature of the skin, b/w 86-97 degrees F
object feels cold bc it is under the physiological zero
object feels hot bc it is above the physiological zero
gate theory of pain
proposes that there is a special “gating” mechanism that can turn pain signals on or off
this affects whether or not we perceive pain
spinal cord is able to preferentially forward the signals from other modalities of touch to the brain reducing the sensation of pain
kinesthetic sense
proprioception
ability to tell where one’s body is in space
knowing where limbs are in space
receptors are found mostly in muscles and joints
play role in hand-eye coordination, balance, and mobility
bottom-up processing
data driven
refers to object recognition by parallel processing and feature detection
brain takes the individual sensory stimuli and combines them together to create a cohesive image before determining what the object is
top-down processing
conceptually driven
driven by memories and expectations that allow the brain to recognize the whole object and then recognize the components based on expectations
brain quickly recognize objects without needing to analyze specific parts
perceptual organization
ability to use these processes to create a complete picture or idea
Gestalt principles
ways for the brain to infer missing parts of a picture when a picture is incomplete law of proximity law of similarity law of good continuation subjective contours law of closure
law of proximity
elements close to one another tend to be perceived as a unit
law of similarity
objects that are similar tend to be group together
law of good continuation
elements that appear to follow the same pathway tend to be grouped together
subjective contours
perceiving contours and shapes that are not actually present in the stimulus
may arise from the law of good continuation
law of closure
when a space is enclosed by a contour it tends to be perceived as more complete (or closed) than they really are
law of prägnanz
perceptual organization will always be as regular, simple, and symmetric as possible
governs the Gestalt principles
