2:1 Perception Flashcards
What are three crucial challenges for perception?
- Incomplete incoming sensory information: Must be interpreted because information is incomplete.
- Too much raw information: There’s a huge amount of info that we don’t need to function well or achieve goals.
- From the incomplete yet overwhelming input, we must extract what’s dangerous or important.
Which sense provides us with the best source of information for interaction with our environment?
Vision.
It’s the only sense to have an entire lobe dedicated to it – occipital lobe.
In which area of the visual field does information enter both eyes?
Vision is binocular (3D) in the central / middle area.
Where is binocular vision projected?
Directly onto the fovea, the middle part of the visual field.
Where are the rods and cones and what are they?
They are on the fovea of the retinas.
They are light receptor cells that are needed in order to see.
When do rods work?
When there is very little light available in the visual field.
Vision in the dark is black and white.
When do cones work?
Cones are sensitive to color information and work only in well-lit conditions.
Cones enable color vision.
Color vision only occurs for the items we’re directly fixating on.
Color information is only processed for items falling onto the fovea.
Binocular vision is only possible for the middle part of the visual field and that color vision only occurs for the items that we’re directly fixating.
After the retina and fovea, what route does visual input take to the LGN?
Visual input leaves both eyes by the optic nerve.
The two sources of input (from left and right eyes) meet at the OPTIC CHIASM and are directed as separated streams to opposite sides of the brain / hemispheres.
From there, visual info goes to thalamus.
The thalamus is a hub for sensory information entering the brain relaying incoming input to relevant parts of the cortex for the more detailed processing.
The area of the thalamus concerned with visual info is the lateral geniculate nucleus (LGN).
Where does visual info go from the LGN?
LGN directs info via optic radiations to the primary visual cortex in the occipital lobe.
Visual cortex = V1 = striate cortex.
What are two important principles of vision?
- Vision is organized HIERARCHIALLY.
- - the most simple properties are processed first and then the more complex properties are added as neural processing continues. - Vision is MODULAR.
- - specific parts or modules in the visual cortex deal with specific types of visual input.
Explain the order of hierarchal vision.
- Dots and lines are extracted from input.
- Edges are added.
- The dots, lines and edges are formed into objects.
- Movements of the object are then added.
* Eg. There is no representation of a chair arriving from the visual input in front of you.
Which area of the LGN deals with the fundamental elements of our visual input?
V1.
If V1 is damaged, we become cortically blind.
Without V1, no further analysis of information is possible.
From V1, visual input makes its way though the other regions.
Which occipital cortical area deals with color?
V4.
Damage to V4 in both hemispheres leads to loss of color vision.
Which area of the occipital visual cortex deal with motion?
V5.
Damage to that area leads to motion blindness.
Name the two visual streams and their roles.
DORSAL stream (top of brain / parietal cortex): WHERE stream.
VENTRAL stream (bottom of brain / temporal cortex): WHAT stream.
