module 3 notes

module 3 notes - The Senses Vision Parts of the Eye Iris:...

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The Senses Vision Parts of the Eye Iris: good for how much let it lets in Pupil: hole Cornea: protective outer surface Lens: right behind pupil, focuses light rays on retina which is in back of eye; inverts whatever image you are seeing Fovea: point of central focus, where you can see the best, lets us see colour (lots of cones) Optic nerve to brain’s visual cortex, takes signals from retina and transmits to brain Retina (back of eye) Light comes into retina 3 types of cells- retina is 3 cells thick Ganglion cell closest to outside; least cells Bipolar is next, start shrinking stimuli down; less cells than rods and cones Visual processors- rods (responsible for black and white vision), cones (colour); millions o Looking out of corner of eye- see less colour b/c more rods Light must go through two layers of cells so that it’s not as strong before getting to rods and cones, which set off neural impulses From Eye to Cortex Part of brain that makes meaning of things is cortex Nerves end up crossing one another Nerves from inside of one eye and outside of other eye come together, same with other pair Place where they do this is called optic chiasm First processing happens in visual area of thalamus Go from thalamus to visual cortex, back part of brain
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Visual cortex takes stimuli (light) and turns it into shapes; this is called feature detection In the cortex there are individual cells that respond to lines at various specific angles They take the symbols of lines and create a pattern of what image you are looking at Cells converge to create our perception of what we see Higher level cells in other parts of brain (in front of cortex) provide even more perception Cortex maps out morphology and higher levels provides interpretation All of this happens virtually instantly Massive parallel processing of information Still not completely understood as to how the visual cortex organizes all this information Colour Vision- two theories Both theories probably true, but in different areas of the brain Trichromatic view: at the retinal level, you have three types of cones which work together to produce all the different colours Opponent-Process view: true in the thalamus, higher up in the brain as it is processing things Oldest theory: Young-Helmholtz Trichromatic Theory, comes primarily from studying retina o Three types of cones in retina, which respond to three types of light; red, green , blue (primary colours) o All other colours can be made from these three o Consistent with this theory are colour-blind individuals o Theory works well until we talk about yellow o Brain responds to yellow as a primary colour Opponent-Process Theory of Colour Vision o Three sets of opposing pairs of colours: red/green, blue/yellow, black/white o Explains after-image effect
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Stare at something green yellow and black and then look at white paper turns out
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module 3 notes - The Senses Vision Parts of the Eye Iris:...

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