chap 5 Flashcards
what is sensation?
the act of using our sensory systems to detect environmental stimuli
what is perception?
the conscious recognition and identification of a sensory stimulus
name 5 types of sensory systems?
olfactory (smell), somatosensory (touch, heat, pain), gustatory (taste), auditory (hearing), visual (sight)
examples of physical stimuli
odourants (airborne chemicals), psi or dmg to the skin, chemicals (typically in food), sound waves, light (photons)
what are sensory receptor cells
specialized cells that convert a specific form of environmental stimuli into neural impulses
sensory transduction
the process of converting a specific form of environmental stimuli into a neural impulse that our brain can read
sensory homunculus?
the somatosensory stirp that senses external stimuli
what is an absolute threshold?
smallest amount of a stimulus that one can detect
what is the difference threshold (just notice difference)?
the minimal difference needed to notice a difference between 2 stimuli
signal detection theory
the response to a signal in every situation depends on an individ’s ability to differentiate between the signal and noise, and on their response criteria
what is sensory adaptation
repeated stimulation of a sensory cell leads to a reduced response
what is bottom up processing?
transduces neural impulses that move successively into more complex brain regions
what is top down processing
perception processes led by cog processes, such as memory or expectations –> using prev knowledge
perceptual set
readiness to interpret a certain stimulus in a certain way (optical illusions)
what are odorants? + their cells?
airborne chemicals that are detected as odours + olfactory receptor neurons (convert signals from odourants to neural impulses.
how do we sense taste?
papilae (bumps on tongue that contain taste buds), taste buds (sensory receptor cells that convert chem signals from food to neural impulses)
what are the 5 taste receptors on the tongue?
sweet, sour, bitter, salt, umami
what sensations also contribute to eating other than smell and taste?
texture –> consistency of food and thus explains why some textures are rejected
what is well developed at birth and why?
smell (newborns have a preference for odor of their mother’s milk), taste is also well developed (preference to sweet and dislike for bitter)
gender diff in taste and smell?
females more sensitive to odours than males, some are more sensitive to bitter substances than others (“super-tasters”)
what is aguesia?
inability to taste
what is anosmia?
inability to detect odours
what is hyposmia?
reduced ability to smell
what is reflex epilepsy
a seizure occurs only after exposure to a specific odour
migraine headaches
specific odours can trigger migraines
what are tactile senses? (5)
pressure, touch, temp, vibration, pain
what are free nerve endings
detect touch, psi, pain and temp -> located near the surface of the skin
what are meissner’s corpuscles
transduce info about sensitive touch -> located in fingertips, lips and palms (hairless skin areas)
what are merkel’s discs?
transduce info about light to moderate psi against the skin-> located near surface of the skin
what are ruffini’s end organs
registers heavy psi and movement of the joints –> located deep in the skin
pacinian corpuscles
respond to vibrations and heavy psi –> deep in the skin
steps to perceiving touch?
- tactile receptors respond to touch and psi and send info to spinal cord
- spinal cord -> thalamus
- thalamus -> somatosensory cortex
- the somatosensory cortex receives the info
what are 2 pathways of pain
fast pathway, slow pathway
what is the fast pathway of pain?
-myelinated path where pain is sharp and localized and felt quicker
what is the slow pathway?
-unmyelinated so pain is often burning and long..
gate control theory of pain
a gate can be closed and prevents pain msgs from being perceived
what is the most common tactile sense disorder?
chronic pain
what relieves chronic pain? (chem, drug, theory)
endorphins and enkephalins are chemicals that have pain-relieving properties, opiates mimic pain relief, gate control theory and touch sensations –> alleviate acute pain
what is familial dysautonomia?
inability to detect pain, temp, and produce tears
what are phantom limb sensations?
hallucinations of touch, psi, vibration, and pain in the body part that no longer exists (ampputated)
what are sound waves
vibrations of the air in the frequency of hearing
what is frequency
-# of cycles per sec in a wave
-determines pitch of sound
-measured in Hz –> cycles per sec
-we hear in 2000-5000 hx the best
what is amp?
-the magnitude (height of a wave)
-determines loudness
measured in decibels (dB)
how does the ear hear? (8)
- sound waves enter the outer ear
- waves hit tympanic membrane (eardrum)
- waves pass into middle ear (ossicles) –> maleus (hammer), incus (anvil), and stapes (stirrup)
- stapes hit oval window –> causes a wave to form in cochlea
- fluid deflects basilar membrane, bending hair cells that transduce the wave into electrical activity
- as hair cells move –> neural impulses sent to the brain
- sound travels to brainstem, thalamus and auditory cortex –> sound is reached in a tonotopic map
- certain frequencies are always received by specific areas of auditory cortex
what is frequency theory
higher frequency sounds produce more rapid firing than low frequency sounds bc diff sound frequencies are converted into diff rates of APs
what is place theory?
diff in sound frequency activate diff regions of the basilar membrane, depends on a particular frequency
what is absolute pitch?
-perfect pitch
-those who speak tonal languages are more likely to develop absolute pitch
-ability to recognize or produce any note on a musical scale
what is sound adaptation
our ears become less sensitive to continuous noises and our brains filter out sounds that are not important
what is the cocktail party effect
brain picks up relevant sounds, even in a noisy environment (e.g. someones name)
what is general loudness?
louder sounds seem closer
what is loudness in each ear?
the ear closer to the sound hears a louder noise than the ear farther from the sound
what is timing?
sound waves will reach the ear closer to the source of the sound before they reach the ear farther away
development of hearing at birth?
-babies can hear before they are born
-ability to recognize and respond appropriately to sounds in the first few months after birth
-infants prefer speech to non-speech (mom’s voice)
what is tinnitus?
ringing in the ear
how does the eye work? (6)
- light enters the eye
- muscles in iris adjust pupil size to control the amount of light allowed in
- muscles also change the shape of the lens to bring the object into focus
- the lens focuses the light on the retina, multi-layered sheet of nerve cells
- photoreceptors (sensory receptor cells for vision called rods + cones) are located in the retina
- photoreceptors tranduce light waves into neural impulses
function of rods?
-detect light
-used for periphery and night vison
-not as acute as cones (fuzzy vision)
-many more rods than cones >100 mil
function of cones?
-used for central and colour vision
-very acute (very clear)
–> fovea (centre of retina) contains all cones
-4.5-6 mill cones
what is hue?
the exp of colour based on the wavelength of light (green, blue, red, and other colours)
what is trichromatic theory?
3 diff sensors for colour and each type responds to diff range of wavelengths of light
–> when we see more than 3 colours, its the variety that arises from combining the 3 colours
what is the opponent process theory?
colour pairs work to inhibit one another in the perception of colour (opposing colour pairs: red-green, yellow-blue, black-white)
–> explains why we cannot see mixes of certain colours..
what are negative afterimages?
when one colour is fatigued when it is viewed for a sustained period of time and the previously inhibited colour is activated (opposite colour of original image)
what is colour blindness?
-inability to distinguish certain colours and cannot see the same range of colours as those w/ normal vision
-shortage of cones
-typically inherited through genetics, disease, medication or aging
what is the visual pathway?
-optic nerve has axons of 1 mill ganglion cells exiting the eye via thalamus and project to thalamus
-from thalamus, neurons project to the visual cortex
what is the ‘what’ pathway?
-the pathway that helps us identify an object and involves axons that travel from occipital cortex to the temporal cortex
-visual agnosia
what is the ‘where’ pathway?
-axons that travel from occipital to parietal cortex
-locating objects in space
-hemi neglect
what is visual agnosia?
-dmg to “what” pathway; cannot visually recognize obj, vision is intact but cannot recognize objs
what is prosopagnosia?
- a form of visual agnosia in which ppl cannot recognize faces
what is hemi-neglect? example..?
-dmg to “where” pathway; ppl ignore one side of their visual field
-eating food on only one side of the plate
-ppl w/ dmg to the right side of their “where” pathways neglect the left side of their visual field
pathway for bottom-up processing?
bottom-up processing –> light –> eye –> neural impulses to complex brain regions –> perception of a visual stimulus
what is proximity? (gestalt laws)
obj that are physically close tgt are grouped tgt
what is similarity?
similar objs are grouped together and perceived as something
what is continuity?
objs that continue a pattern are grouped tgt
what is closure?
we fill in small gaps in obj so that they are perceived as whole objs
what is figure ground?
the tendency to perceive one aspect as the figure and the other one as the background
what are binocular cues?
cues from both eyes
what is retinal disparity?
diff images of obj are cast on the retinas of each eye
what is convergence?
the tendency of the eyes to move toward each other as we focus on objs up close
what are monocular cues?
cues from one eye
examples of monocular cues? (8)
relative height, relative size, texture gradient, linear perspective, familiar size, light + shadow, clarity/aerial perspective, motion parallax
what is relative height?
we see objs that are higher as farther away than those that are lower
what is texture gradient?
we see more details of texture as closer
what is familiar size?
when we look at 2 objs we know are about the same size, if one seems smaller than the other, we see it as farther away than the other
what is linear perspective?
parallel lines seem to converge in the distance
muller lyer illusion?
-2 lines that look diff but are the same length
-double arrows
what is the ponzo illusion?
converging lines make the upper bar seem larger, but both bars are identical in length
what is pavement patty?
illusion of a flat decal to create a 3d image which plays w/2d depth cues
what is perceptual constancy?
top-down tendency to view objects as unchanging, despite shifts in environmental stimuli we receive (e.x size of the moon)
what is size constancy?
we perceive objs as the same size regardless of the distance from which its viewed
what is shape constancy?
we see an obj as the same shape, no matter from what angle it’s viewed
how does sight develop?
-newborns can see, but vison improves significantly by 2 months (however focal range is only limited to a foot)
-8 months–> visual acuity is similar to adults
-exp w/ visual world is necessary for normal visual system development
what is strabismus?
-lack of movement of both eyes (2-4% of pop)
-2 diff images sent to brain and there is either results in visual loss or the brain ignores images from the weaker eye.
what is amblyopia?
a loss of visual abilities in a weaker eye –> abnormal development of brains visual cortex due to failure of visual stimulation in both eyes by age of 6
visual impairments and loss?
500,000 in canada have visual impairments and 50,000 lose their sight each year
how do ppl adapt to visual impairments?
braille–> combos of raised dots for reading
kinesthetic senses?
receptor cells in muscles tell the brain WHEN we are moving and WHERE our body parts are in space
vestibular senses?
located in semicircular canals of inner ears–> movement of fluid tells if we are standing up or swaying side to side
