Perception Flashcards
sensory processing
interpreting information our senses receive from the environment
vision is interpretive
vision is constructive
brain interprets visual input
brain constructs representations of the world around us
our sensory impressions are influenced by :
the contexts in which they take place
our emotional state
our past experiences
the retina
two types of photoreceptors
cones = colour sensitive, densely packed in fovea rods= night vision, black and white
retinal ganglion cells
group of retinal neurons with axons that give rise to the optic nerve
vision - from the eye to the brain
visual information leaves both eyes via the optic nerve
info from each eye crosses over in optic chiasm and goes to the opposite hemisphere
goes through the Lateral Geniculate Nucleus (LGN) directs info to the visual cortex in the brain
vision is hierarchical
brain starts by processing most simple properties and works its way up as processing continues
vision is modular
specific areas of the brain deal with specific informations
V1
primary visual cortex
most info from LGN comes here
Left V1 contains a retinotopic map of the entire right visual field, while right V1 contains a map of the left visual field.
Loss/damage of V1
loss= cortical blindess damage= blindness in related part of visual field
Blindsight
ability of people who are cortically blind due to lesions in their primary visual cortex (V1) to respond to visual stimuli that they do not consciously see.
V4
V4 important for colour perception, and some neurons in V4 respond well to more complex features or combination of features.
Damage of V4
Damage to both V4s can lead to loss of colour vision
Inability to identify or discriminate colour
Damage to V4 in only one hemisphere can result in a loss of color perception to one side of visual space.
Processing of form and motion is preserved
V5/MT
The middle-temporal – MT – area is important for motion perception. Almost all neurons in area MT are direction-selective, meaning that they respond selectively to a certain range of motion directions and not to others.
Damage to V5
V5 deals with motion information
Damage to both V5s = Motion Blindness
