Colour Vision 1 + 2 Flashcards
What are the problems with perception?
- The environment
- The reality
- The sensory system of the brain
What is an example of a challange that comes with perception?
If there is a vast amount of information in the environment, it is tough for the brain to perceive all the information at once.
The greater the stimuli, the harder it is.
Cognitive resources are ___ ___, which are quickly ___.
scarcely, limited, depleted
Give two examples of visual records within the visual system.
- Vison is not rich in detail, eye movements are goal-directed.
- Mental imagery used the same brain areas as teh visual perception system.
Eye movement are goal-directed meaning ___.
That vision is not a passive process.
Name three types of ganglion cells.
- Midget cells.
- Bistratified.
- Parasol cells.
What is the purpose of midget cells?
Midget cells are a type of ganglion cell, they project to the parvocellular layers of the lateral geniculate nucleus.
Where are midget cells found?
They are found in the ganglion layer of the retina.
What colour channel are the midget cells responsible for?
The red-green colour channel.
What colour channel are bistratified cells responsible for?
The blue-yellow colour channel.
Where are bistratified ganglion cells found?
They are found in the ganglion layer of the retina.
What are two kinds of bistratified ganglion cells.
Where are parasol cells located?
In the ganglion cell layer in the retina.
What is another name for parasol cells?
M-cells.
Define vision perception.
Vision perception is the brains’ ability to receive, interprut and act upon visual stimuli.
What are the seven elements that perception is based on?
- Visual descrimination.
- Visual memory.
- Visual-spatial relationships.
- Visual form constancy.
- Visual sequential memory.
- Visual figure/ground.
- Visual closure.
Define visula discrimination.
Visual discriminatio is the ability to distinguish from one shape from another.
Define visual memory.
Visual memory is the ability to remember a specific form when it is removed from your visual field.
Define visual-spatial relationships.
Visual-spatial relationships is the ability to recognise forms that are the same but different in a different spatial orientation.
Define visual form constancy.
Visual form constancy is the ability to discern similiar forms that are the same but may be different in size, colour, or spatial orientation and to consistantly match the similar form.
Define visual sequenctial memory.
Visual squential memory is the ability to recall two to seven items in a sequence with vision occluded.
Define visual figure/ground.
Visual figure/ground is the ability to discern forms when camouflaged or partially hidden.
Define visual closure.
Visual closure is the ability to recognise familiar forms that are only partially completed.
What are the six layers of the lateral geniculate nucleus.
- Magnocellular
- Magnocellular
- Parvocellular
- Parvocellular
- Parvocellular
- Parvocellular
What are M-cells?
M-cells are neurons located within the adina magnocellular layer of the lateral geniculate nucleus of the hypothalamus.
What are P-cells?
P-cells are neurons located within the parvocellular layers of the lateral geniculate nucleus of teh thalamus.
What are K-cells?
K-cells are neurons with a small cell body located in the konicellular layer of the lateral geniculate nucleus (the part between the six layes).
What is the V1, V2, V3, V4, V5 selective for?
They are selective for the following:
- Orientation.
- Colour.
- Binocular disparity.
- Motion direction.
What does the visual system: V1 selective for?
It is involved in:
- Colour contrast.
- Achromatic contrast.
- Ocular dominance columns.
- Orientation columns.
What is binocular disparity?
Binocular disparity refers to the difference in image location of an object seen by the left and right eyes resulting from the eyes’ horizontal separation (parallax).
What are the visual processing streams and anatomical pathways?
Dorsal and ventral
Magnocellular and parvocellular
Stimulus attributes:
- M: motion, depth: larger
- P: form, colour: smaller
Why is there connectivity between the processing streams and anatomical pathways?
For:
- Efficient communication
- Integration of information
What pathway does the object discrimination task refer too?
(Ungerleider and Mishkin, 1983)
The ‘what pathway.’
What pathway does the landmark discrimination task refer too?
(Ungerleider and Mishkin, 1983)
The ‘where pathway’.
Perceptions are an ___ process and they imform us about ___ aspects of our ___.
active, important, environment.
Representations of objects are ___, in a layered way, by ___ sub-systems.
constructed, specialised.
Visual perception is special as it ___ ___ about ___ objects.
conveys messages, distant
Perceptions aid ___ as they enable us to take ___ and ___ when it comes to spotting predators, food, or healthy mates.
survival, decisions, actions
Why do we need colour vision and what is it?
- Colour is about communication.
- About object segregation.
- Perceptual words depend on the beholder which also depends on the species. Humans are trichromats.
- There is no such thing as color, it is a construct that is based on physics, e.g., sunlight hitting an object and generating a colour by reflecting it (‘what pathway’). If the individual has stored knowledge, they decide what to do with it.
Name the three different cones.
S, M, and L cones.
Where does S cones lay?
They lay on a specific chromosome.
What does S-cones stand for?
Short wavelength cone.
What does M-cones stand for?
Medium wave-length cone.
What does L-cones stand for?
Long wavelength cone.
What are S-cones mediated by? and what chromesome?
They are mediated by a gene on the band called q38 on the chromosome 7.
What are M-cones mediated by? and what chromesome?
M-cones are mediated on the X chromosome on a band called q28 (q = long arm).
What is the percentages/ratios of the cones in the fovea?
Typically there are twice as many L-cones as M-cones and S-cones only make up around 5% (the structure is random).
What is a complex cell?
A cell type of the visual cortex that responds best to a light stimulus of a particular shape anywhere in its receptive field; its receptive field cannot be mapped into fixed excitatory and inhibitory zones
What is a cone?
A type of retinal receptor that contributes to color perception
What is the dorsal stream?
The dorsal stream is the visual path in the parietal cortex, sometimes known as the where or how pathway
What is the lateral geniculate nucleus?
A thalamic nucleus that receives incoming visual information.
What is the primary visual cortex area: V1?
An area of the cortex responsible for the fi rst stage of visual processing.
Define prosopagnosia.
An impaired ability to recognize or identify faces.
What is a cone?
A type of retinal receptor that does not contribute to color perception.
What is a saccade?
A saccade is the ballistic movement of the eyes from one fixation point to another.