Visual Processes and Object Recognition Slides Flashcards
trichromat
someone with normal vision
two kinds of hereditary color deficiency
- red or green cone peak sensitivity shifted
- red or green cones absent
visual acuity
how accurately light is focused on retina
area v1
primary visual cortex
striate cortex
v1 cells code…
lines, orientation, and direction
simple cells
respond to elongated bars or edges orientation selective monocular or binocular separate on or off length summation
complex cells
orientation selective
homogenous receptive field
almost all binocular
length summation
blindsight
cortical blindness from damage to v1 results in hemianopias and scotomas
hemianopias
loss of half of visual field
scotomas
loss of small portion of visual field
pathways to higher visual areas can…
bypass V1
corticol blindness from damage to V1 causes…
hemianopias and scotomas
extrastriate cortex is composed of
areas v2 and v3
area v4
receives input from v2 and v3
primary source of input to ventral stream
perception of fine detail and color perception
damage to v4 can cause
acromatopsia
congential achromatopsia
no cone cell activity at all
black and white vision
extrastriate
v5
v5
MT region
speed and direction of motion
structure from motion
guidance of eye movements to moving targets
akinetopsia
caused by MT damage
deficit in motion perception
multimodal perception
areas that combine signals from multiple sources
Superior colliculus
superior temporal sulcus
synesthesia
mixing of sensations
two types of synesthesia
projectors
associators
projectors
experience the color in the outside world
associators
experience the change internally
structure of synesthesia
increased connectivity in visual areas (more for projectors)
in fMRI synthesthetes present with…
greater activity in primary cortex
structure where a large difference is shown between synthesthete and control
v4
illusions
v1 generally silent to visual illusions
higher visual areas respond to illusions in ventral stream
perceptual reorganization
cortical plasticity
ex: blind recruit visual cortex for tactile discrimination
region associated with ventral stream
occipitotemporal cortex
region associated with dorsal stream
posterior parietal cortex
