Perception Flashcards
sensation
how your senses transform physical properties of the environment and body into signals relayed to the brain
perception
process of organising, selecting, and interpreting these signals. determines what we believe is real
six senses for humans
vision, hearing, somatosensation, taste, smell (olfaction), vestibular
the problem of qualia
all our different senses transform their physical input into the same electrical impulses in the brain - why do we experience them as different senses?
problem of illusions
if our senses can make errors, how do we know what is real?
importance of illusions
provide insight into how perceptual systems break down
dimensionality problem of taste
there are so many different chemicals in the world, it is not possible to have receptors to detect all of them with a finite sized sense organ
papillae
gives the tongue its bumpy appearance. has 4 types
4 types of papillae
filiform, fungiform, foliate, (circum)vallate
we have an innate preference for
sweetness
super-tasters
some humans are genetically prone to have more fungiform taste receptors around the tip and sides of their tongue
super-tasters are more common among
asians, africans, and women
spicy is not
a taste
distance sense
smell provides info about chemicals suspended in the air around us
dogs vs humans
dogs have a much bigger olfactory bulb and nose, therefore bigger sample of air
adaptation
we cannot escape the smell of ourselves, so we are always in some state of olfactory adaptation
flavour =
taste + smell + temperature
pheromones
separate set of sensory receptor cells in many mammals’ noses to receive social and sexual info from members of their own species
two major subsystems of the “body senses”
somatosensory system, introception
somatosensory system =
touch and proprioception
introception
the sense of the physiological condition of the body
importance of touch
there is an intimate relationship between touch and emotions
dynamic sensitivity in skin senses
tactile afterimages, tactile adaption, active vs passive touch
tactile afterimages
texture contrast after effects (after touching something rough, a medium rough surface feels smoother)
tactile adaption
importance of movement in perceiving spatial patterns in the skin
active vs passive touch
the tactile system has evolved to perceive best when it is exploring
two subsystems of somatic sensory system
detection of mechanical stimuli, detection of pain and temperature
mechanosensory processing
detection of external stimuli, proprioceptors
proprioceptor
receptors located in muscles, joints and other deep structures, respond to position and movement
3 groups of receptors
mechanoreceptors, nociceptors, thermoceptors
nociceptors
terminate in unspecialised free endings, so categorised according to the properties of the axons associated to them. three classes
thermoceptors
not understood very well, sensation of hot and cold
two types of touch fibres
rapidly adapting and slowly adapting
rapidly adapting touch fibres
info about change or dynamical quality of stimuli. meissner corpuscles, pacinian corpuscles
meissner corpuscles (type of rapidly adapting touch fibres)
elongated receptors that contain one or more afferent nerve fibres that generate action potentials following minimal skin depression. found beneath epidermis of fingers, palms, soles of feet
pacinian corpuscles (type of rapidly adapting touch fibres)
large encapsualtions and found in subcutaneous tissue and gut
slowly adapting touch fibres
info about shape, edges, rough texture, persisting features. merkel disks and ruffini organ
merkel disks (type of slowly adapting touch fibres)
located in the epidermis. 25% in hand
ruffini organ (type of slowly adapting touch fibres)
arent well understood. elongated spindle structures located deep in the skin, ligaments, and tendons
hyperalgesia
abnormally heightened sensitivity to pain
the vestibular system of the ear
assists with the control of gaze and posture
the inner ear contains
sensory structures with receptor cells that detect gravitational forces, including angular and linear head accelerations in space
the vestibular sense organs
the labyrinth of each ear houses 5 sensory organs which provide input to the vestibular system. three semicircular canals and two otoliths
spinning
feelings after spinning relate to the effect of fluid flowing into the semicircular canals, which bends the cupula and underlying hair cells
benign paroxysmal positional vertigo
mechanical problem in the inner ear occurs when calcium carbonate crystals become dislodged and move
sound as a wave - transverse waves
electromagnetic waves e.g. light vibrations through solids and liquids. longitudinal waves - sound waves and perception
sound and perception
amplitude, frequency, purity
the middle ear
transmits the eardrum’s vibrations to the oval window, which transmits them through the fluid-filled cochlea. consists of the ossicles and perilymphatic fluid
the ossicles consists of
the three smallest bones in the human body - malleus, inus, stapes
the inner ear consists of
semicircular canals and the cochlea
cochlea
vibrations at oval window cause basilar membrane to wiggle. the output of the cochlea is transmitted to the brain through the auditory nerve
how does the basilar membrane wiggle
the whole thing moves at once like a diaphragm. problem with this = the basilar membrane varies in thickness and stiffness
phase-locking
occurs for frequencies under 4kHz
2 cues to the frequencies in a sound
the place of excitation in the cochlea, frequency of firing
three main sources of info about sound localisation
interaural intensity differences, interaural time differences, spectral info
three stages of vision
form an image, transduce light energy into electrical impulses, transmit this info to the brain for interpretation
image formation
light is an electromagnetic wave
types of eyes
compound (flies), convex mirrors (sea scallops), concave mirrors, pinhole, single chambered (humans)
refraction
light bending when the optical density changes
hyperopia
eye too short (far sighted) - hyperopia connected
myopia
eye too long (short sighted) - myopia connected
accommodation
lens accommodation allows us to adjust our focus on objects at different distances
photoreceptors
duplicity theory of vision. use two different classes of photosensitive receptors that operate in different luminance regimes
mechanisms of light adaption
pupil dilation/contraction, isomeristion of the photopigments
retinal distribution of rods and cones
rods:cones = 2:1
rods
night vision - scotopic vision
cones
daylight vision - photopic vision
trichromatic theory
different colour experiences are due to the activation of just three receptor types
trichromacy
colour is closely related to the proportions of responses of the three different types of cone receptors
trichromatic theory of colour vision
millions of different perceived colours can be explained in terms of the responses of the three cone types
centre-surround receptive fields
the receptive field of a visual cell is the retinal area that, when stimulated, can affect the firing of that cell
colour-vision defficiences
defects in genes for making pigments in cones. 3 main types = red-green, blue-yellow, complete
the lateral geniculate nucleus
performs further integration of info from the eye concerning colour, form, and motion. projects visual info to primary visual cortex
retinotopy
adjacent points in the visual field project to adjacent location in the visual cortex
depth perception is linked to
perceived size
oculomotor cues
accommodation (far and near things), convergence (depth by sensing the angle of fixation)
monocular cues
aerial perspective, linear perspective, 123 point perspective, motion parallax
