week 5: sensation and perception Flashcards
parts of the eye
cornea pupil aqueous humour iris lens vitreous humour retina fovea optic nerve blind spot
what is the retina?
the retina is similar to a camera
receives light from the lens and converts it to neural signals for the brain to process
Ganglion cells
inside the retinal
Ganglion cells have receptive fields and act as edge detectors. Rods and cones within the ganglion cells are able to pick up contrasts
what is selective focus?
the ability to focus on an item and blur the remaining visual information
what is the fovea?
the fovea is the exact centre of the visual field where the light rays enter they eye straight along the axis of the eye
what part of the eye has the greatest concentration of photoreceptors?
the fovea due to it representing the location the eye is pointing when looking at something
what are the types of photoreceptors?
cones
rods
cones photoreceptors
colour vision
high acuity (can see detail)
work in bright light
daytime photopic vision
rods photoreceptors
black and white vision low acuity (ability to see detail) widely spaced within the retina and more in the peripheral visual field nighttime vision night time scotopic vision
what is scotopic vision?
vision in low light
what is photopic vision?
vision in well lit lighting
visual controlateral arrangement
the left visual field of both eyes projects to the right hemisphere of the brain. the right visual fields of both eyes project visual information to the left hemisphere of the brain.
how does visual information travel to the brain?
nerve cells travels from the controlateral eye over the optic chiasm (midbrain) to the lateral geniculate nucleus of the thalamus then to the occipital lobe in the back of brain
where is the primary visual cortex?
the occipital lobe
what does the primary visual cortex do?
receives, integrates and processes visual information relayed from the retina
what are the cells within the primary visual cortex?
simple cells
complex cells
hypercomplex cells
simple cells
respond to an edge at a particular orientation in a specific part of the visual field
complex cells
respond to an edge at a particular orientation but falling anywhere within a wider field
which cell with the primary visual cortex can respond to direction of motion?
complex cells
hypercomplex cells
responds to a line which ends within the receptive field
what are higher levels of visual processing?
Other regions of the brain aid in processing the visual information
- temporal lobes detect combinations of lines/edges eg, squares or cones
- colour and orientation combinations
what is agnosia?
visual disorder where individuals are unable to recognise objects
what is prosopagnosia?
A specific form of agnosia where individuals cant recognise faces
what does damage to the parietal lobe mean for vision?
cause problems with spatial awareness
- visual neglect
what is visual neglect?
hemineglect
visual neglect for hemineglect is when one whole side of the visual field is lost caused by damaged to one side of the visual pathway
what is a visual map?
the information from all levels of the visual system is distributed into multiple maps to indicate where things are in the visual field
retinotopic visual map
mimics the layout of the visual field
how are visual maps weighted?
centre weighted
central 5 degrees represented most strongly
what is visual blindsight?
unconscious awareness of a visual stimulus
how does light travel through the eye?
light enters the pupil and travels through the lens and then vitreous humour to the retina. photoreceptors in the retina convert visual information into communicable information for the brain
