Optic Shit- Exam 2 Flashcards
The physical property of a wavelength is psychologically converted into what?
Colour perception
What two types of ways to describe light? And what is more common in psychology?
Wave length and particles called photons. Wavelengths more appropriate in psyc
The physical property of intensity is converted into what psychologically?
Brightness perception
What is the function of the iris?
Regulates amount of light reaching the retina.
When an image is in close vision, the pupils are…
Constricted
pupils dilate for what two conditions?
Small amounts of light and far objects
What is the function of the lens?
Focussing light onto retina
What part of the eye converts light into neural signals and conducts them toward the CNS?
The retina
Light hits the back of the eye first and then travels forward towards the retinal ganglion cells for neural transportation, what two problems does this create in vision?
- Light is lost in absorption by other cells
2. The ganglion cells leaving the eye creates a hole in vision called “the blind spot”
How is the “blind spot” fixed?
By “filling in”. The brain takes the information from the surrounding images to perceive an image where the blind spot image should be
What part of the eye fixes the light absorption problem caused by inside out processing of light?
Fovea- curvature that allows cell body’s and layers to thin out in the retina area.
What are the two types of vision receptors are there and what do each of them specialise in?
Rods and cones.
Rods- poor colour coding and image resolution but good for being able to see in the dark
Cones- good colour and image resolution but poor in the dark.
Photopic vision relates to high amounts of what receptor?
Cones
Scotopic vision relates to high amounts of what photoreceptors ?
Rods
What is visual transduction?
The conversion of light into neural signals
What pigament underpins rod-mediated vision?
Rhodopsin
Explain lateral inhibition. Give an example.
Helps determine the edge of one object from the edge of another by over-compensating in differences of brightness. E.g. Mach bands
If I wanted to bring an object into sharp focus, what would I have to do with my lens?
Bend lens or make more cylindrical to refract light
I would have a flat lens when…
Focusing on distant objects
What is the first point of organisation of neural signals of vision?
The lateral geniculate nucleus (LGN)
What are the basic 3 stages from retina to primary visual Cortex?
Retina- Lateral Geniculate Nuclei (thalamus) - primary visual cortex
How many layers are in the LGN?
6
The parvocelluar layers make up how many lateral geniculate nuclei layers? Give basic information about parvocelluar system.
First 4 layers.
Parvo= small therefore contains small cell bodies
Is responsible for colour and stationary objects and therefore receives information mostly from cones
The magnocellular layers make up how many lateral geniculate nuclei layers? Explain the magnocellular layers function.
Last 2 layers.
Magno= large therefore contains large cell bodies
Responsible for motion and large receptive field, it receives most of its info from rods.
What is occlusion?
When a darker object is placed in front of an opaic object to make it seem closer.
What is stereopsis?
The appreciation of the 3rd dimension after the brain has perceived the images from each eye.
What is a pro of binocular summation?
The eyes are more sensitive to dim light.
At what region in the eye has the highest spatial aquity ?
Fovea