Vision Flashcards
cones
detect color
fine detail
in fovea
one cone per ganglion cell
rods
night vision
in periphery
lots of rods per ganglion cell
receptive field
an area in visual space that excites or inhibits a cell in the brain
point-to-point topographic representation
A receptor at a point on the skin (or the retina) projects to a specific point in cortex
on-center/off-surround cells
are excited when light hits center of the receptive field and are inhibited when light hits the periphery of the RF
off-center/on-surround
inhibited when light hits the center of the RF and excited when light hits the periphery of RF
trichromatic theory
3 different types of cones, but the cones don’t have a specific sensitivity
opponent-process theory
we perceive color in terms of opposites
explains after-images
retinex theory
the perception of color changes relative to its background or the light shown on it
explains
explains color constancy
color constancy
the ability to recognize colors despite changes in lighting
lateral inhibition
the retina’s way of sharpening contrasts to emphasize borders of objects
the reduction of activity in neighboring neurons when one neuron gets stronger input that the others
mach band
non-existent strips that emerge as a consequence of contrast enhancement
simple cells
Respond to a line at one particular location with one specific orientation
Small RF
complex cells
Respond to a line in a specific orientation almost anywhere in RF
Have medium sized FR’s
hypercomplex cells
Respond to bar of light anywhere in RF
Very large RF’s
good edge detectors
Magnocellular (dorsal) stream
"where/how to" pathway larger cell bodies and receptive fields distributed evenly throughout retina detects movement and sudden changes fast transmission parietal
parvocellular (ventral) stream
"what" pathway small cell bodies/receptive fields in fovea detect visual details and color slow transmission temporal
V4
color form
V5
motion
akinotopsia
the inability to perceive movement
associative agnosia
don’t know the purpose/use of an object
but can still name objects by different modality (like touch)
damage to ventral stream
apperceptive agnosia
can perceive features but can’t put features together to make a whole
damage to ventral stream
prospagnosia
inability to recognize faces
damage to dorsal stream
fusiform face area
activated during facial recognition more than object recognition
William’s syndrome
genetic condition where people show great interest in people and spend more time looking at their faces
enlarged fusiform face area
blindsight
the ability to respond in limited ways to visual info without perceiving it consciously
complete damage to V1
hemispatial neglect
one neglects the left-most side of space
damage to right parietal lobe (dorsal stream)
the binding problem
question of how the visual, auditory and olfactory aspects of an object are combined to within a single object
hypothesis: binding perception depends on simultaneous activity in various brain areas
horizontal cells
inhibitory
amacrine cells
inhibitory
bipolar cells
excitatory
ganglion cells
excitatory
saccade
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blind spot
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