Cognition 1 Flashcards
(123 cards)
Describe the Cornea
Curved transparent part of the eye that counts as ¾ of the ‘lens’ for the eye and lets light through.
Describe the Lens
This part focuses the light entering the eye onto the retina at the back of the eye.
Describe the Iris
The coloured part, provide adjustable aperture for the pupil.
Describe the Pupil
Hole in the centre of the iris which can contract and dilate depending on the amount of light entering the eye.
Describe the Retina
Made up of photoreceptors at the back of the eye, where the actual visual processing really begins
Name the two types of Photo receptor
Rods and cones
Describe the function of Rod cells
All rods are basically the same and they all contain the same photo pigment. Rods react well to dim light, making them almost completely useless in well-lit conditions
Describe the function of Cone cells
Cones come in three main types, long, middle and short wave cones. They work in well-lit conditions and are heavily centred in the fovea (centre).
Describe the path an image takes to get from the eye to the Primary Visual Cortex
Retina - Optic nerve - paths cross at Optic Chasm (50% split) - Optic Tract - LGN - Primary Visual Cortex (V1)
What does light do when it hits the ON region?
Increases the clicking rate
What does light do when it hits the OFF region?
Decreases the clicking rate
What is Luminance?
The amount of light energy something reflects - a physical property
What is Lightness?
How bright something looks - a perceptual property
Where is the primary visual cortex located?
The Occipital lobe at the back of the brain.
What did Hubel and Wiesel discover about the cells in V1?
That cells close to each other in VI have receptive fields close to each other on the retina.
What are the four types of cues?
Motion, Phsyical, Stereo, Pictoral
What does Euclid’s principle say?
Retinal image size halves as the distance to the object doubles.
Describe Stereo Cues
Binocular Disparity - the slight difference between the image on the right and left retinas
Describe Monocular Cues
Motion Parallax - when a person moves the images of the objects around them move across the retina, the closer an item is the faster it moves.
Physical Cues
Accommodation - this is how the eye focuses light to stop it being blurry, muscles moving in the eye signal distance.
Vergence - – Convergence of the eyes (cross eyed) is needed to fixate the image of a nearby object on both foveas. The angle of convergence gives the distance of the object. Is not very useful at telling us information about distance when objects are far away.
Pictorial cues
Occlusion – covering the image of a further object by the image of a nearer one.
Image size – A nearer object produces a larger image than a farther object of the same size.
Texture – a gradient of texture element size and shape provides a cue for distance over a surface.Shading – Gives clues as to the angle of an object
Where does object recognition happen?
In the lateral occipital complex
What happens if the Lateral Occipital cortex is damaged
Visual Form Agnosia
What are the two types of Visual Form Agnosia?
Associative and Apperceptive