Vision 1 Flashcards
Who says vision is innate
Descartes
Who says vision is learnt
Berkeley
What did Wundt say vision is based on?
Perception arises from combining indivisible elements called sensory atoms which is coded in the retina. The direct correspondence between the retina and conscious awarenesss with no recourse to internal mental representstikns. Theory based on introspection
What did behaviorism argue?
Behavior is driven by environment rather than internal mental processes. It is a passive resonance with incoming info
What is Gibsons 1966 theory of direct perception
Visual behavior is based on detecting stable, unchanging aspects of the visual environment which he called perceptual invariants
Two types are optic flow (judge speed/direction) and texture (judge depth)
It comes from perceiving the wholistic image to see objects that can’t be inferred from the parts. Conveyed by light entering the eyes
What is the behaviorist model
Environment leads to behavior and sensory perceptions/memories/beliefs /emotion/ideas
What is the cognitive model?
Environment leads to sensory perceptions/memories… to behaviour
Cognition consists of an orderly series of mental events that actively reconstruct the retinal input. This is the detection of perceptual invariants. These can be studied through experiments
How do we know our view is an interpret of visual works not a physical copy?
Visual illusions,ambitious figures (if lerfeothon was determined by pattern hitting the eye could only see one thing
Impossible figures
What did newton 1672 do
Discovered light can be spilt in to colours from different part of the electromagnetic spectrum.
These are captured by cones red, green and blue
Facts about the human retina
Over 7 million cones and 125 million rods in the retina
Each cone/rod responds differently to light from different parts of the visual fields
The point all nerves converge is a blind spot in the retina
Golden eagles compare to human vision
Can see things moving from a mile away
A buzzards vision is 6-8 times better than ours
They have v large eyes to maximize amount hitting the retina. Buzzards gave 1000000 receptors per mm2 we have 200000mm2
They have high curvature in the fovea
Fewer blood veseels in the retina so incoming light is less scattered
What are the three layers of the human retina?
Photoreceptors, bipolar cell and ganglion cell layers
What is the photoreceptors layer made up of?
Rods and cones
What is the bio polar cell layer made up of
amacrine cells and horizontal cells
What is ganglion cells leather?
Ganglion cells. AP from light absorbtion is submitted here
Mango cellular cells are sensitive to motion parvo cellular cells are sensitive to light intensity
What are receptive fields?
Each photoreceptor is sensitive to a small area of the visual field. This stimulates adjacent areas of the visual field. Topographical organisation. Primary visual cortex preserves it but higher areas normally lose it
What are some gestalt principles
Similarity, proximity, good continuiation, closure, connectedness, common ground
What did wilkinson and Halligan 2002 do?
Low inter-distractor similarity activates the brain more than high inter-distracted similarity
What is temporal oarietal damage do?
Damages global/local perception
How does texture help
Helps organise the perceptual world look for natural discontinuitie. It is immediate and effortless
process of incoming light
The light is absorbed by retinal photoreceptors which, via a process known as isomerization, immediately discharge an action potential
The action potential is transmitted to ganglion cells and thereon to the optic nerve and brain
Adjacent photoreceptors are sensitive to adjacent areas of the visual field. We refer to this organisation as topographical.
