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Lecture

January 22.docx

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Department
Psychology
Course
PSYC 2390
Professor
Lana Trick
Semester
Winter

Description
January 22, 2013 Sensation and Perception 1. Parts of the eye—the iris - focusing bends the light so that the light can focus on a certain point in their sight - when its dark out your pupil is large so it can let in a lot of light and vice versa when it is light - the iris cant go as wide as you get older; senile myosis - albinism is a disorder associated with the iris in particular and the pupil - the iris has melanin in it which gives colouring to the iris as well as the whole body; explains hair colour, skin colour, etc - the more melanin you have, the darker you’ll be; blue eyes don’t have much melanin whereas brown eyes do - albinos were born without melanin; you see a reflection of the blood vessels in the iris and it therefore looks pink or red - albinos have serious vision problems; visual acuity problems; many are legally blind and cant drive - genetic disorder that lets too much light into the iris 2. The lens - the lens and cornea work together to focus the light - cornea does 75-80% of the focusing but the lens does the rest and is a flexible structure - the ciliary muscle changes the shape of the lens depending on the distance of the object you are looking at - yellowish tinge from the lens protects the eye from ultraviolet light; some animals can see ultraviolet light 3. disorders of accommodation and cures - accommodation; you have to bend light rays by rounding out your lens so that you see things that are near or flatten your lens to see things that are far - disorders include: - Myopia; nearsightedness; you can get axial myopia which is someone who is born with an elongated eyeball and therefore looking at things that are far away will be out of focus but things that are close are super focused/refractive myopia is when your lens and your cornea together are too powerful - Glasses for nearsightedness means you have concaved glasses lens’ that curved inward; light rays are artificially widened - Excimer laser surgery; parts of the cornea are shaved off which makes the lens and cornea less powerful and therefore gives a better ability to see far things - Hyperopia (farsightedness); expert at far things and cant see things that are near because they cant bend the light enough and therefore the focal point ends up being behind the eye - The ciliary muscles try to bulge up the lens as much as possible but its not enough and then the person gets eye strain - Someone with axial hyperopia has a flattened out eyeball that is shortened - Refractive hyperopia means that the cornea and the lens together don’t bend light enough when things are close - For hyperopia you need a convex lens which bulges outwards and compensates for your own lens that doesn’t bulge enough; when you look at an object that is near and has a lot of light angles, your glasses lens narrows them artificially so they will focus at the back of your eye - Presbyopia (presb means old); your lens grows like an onion and the lens tissue gets more and more packed and therefore doesn’t bend very well and you cant see things that are near very well anymore - Someone who is nearsighted their whole life and grows old; they will develop presbyopia and
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