PSC 131 Study Guide

PSC 131 Study Guide - Class Notes for PSC131 (Midterm 1)...

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Class Notes for PSC131 (Midterm 1) Photons to Brain I. Light a. Visible light includes electromagnetic wavelengths between 400 – 700 nanometers b. Appearance of light depends on its wavelength i. The physical variable of light is its wavelength (i.e., no such thing as “blue” light) ii. The psychological variable of light is its color c. How light interacts with matter… i. Each of these types of interactions requires light to pass through matter that is a different density from the matter surrounding it (e.g., glass with air on either side) 1. Absorption – light is absorbed into (i.e., gives energy to) the matter 2. Reflection – light bounces off of the matter 3. Refraction – light bends through the matter a. Different wavelengths of light are refracted at different angles ii. Lenses (in the eye) work the same way, refracting light d. How lenses work… i. The lens produces an upside-down view of the visual field on the back of the eye ii. The thickness of the lens determines the degree to which the light is refracted
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II. The Human Eye a. Cornea – transparent cover of the eye that has many pain receptors (i.e., protects eye) i. Refracts light to a certain degree, which helps the lens to focus the visual field onto the retina ii. Contacts work by reshaping the cornea to refract light either more or less b. Aqueous Humor – watery stuff that helps to give the cornea its shape c. Iris – donut-shaped tissue that dilates or constricts, depending on whether your eyes need to let in more or less light (i.e., depending on whether you are in a dark or light room) i. The autonomic nervous system determines whether you are aroused (i.e., fight or flight response, general anxiety) or relaxed 1. The sympathetic nervous system increases arousal, leading to dilation of the iris (along with increased heart rate, breathing, sweating, etc…) 2. The parasympathetic nervous system decreases arousal, leading to constriction of the iris (along with decreased heart rate, etc…) ii. Studies have found that images of the same person are deemed more attractive if that person displays dilated (rather than constricted) irises 1. Also, when people look at someone attractive, their irises dilate 2. Furthermore, when people are young their irises are able to dilate to a greater degree than when they are old 3. Think about how these two phenomenon may be related to attractiveness d. Lens – refracts light into the eye, focusing it onto the retina i. The lens is able to change shape in order to focus light sources (e.g., light coming off of objects) that are either near and far away from the eye ii. This flexing of the lens is known as “accommodation” e. Vitreous Humor – watery stuff that helps to give the eye its shape f. Retina – absorbs light and transduces it into chemical energy (i.e., neural activity) i. Neural activity travels from the retina down through the optic nerve g. Choroid – dense network of blood vessels that feed, and take waste from, the retina h. Sciera – hard, white shell that helps to give the eye its shape
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III. Types of Refractive Error
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This note was uploaded on 04/20/2010 for the course PSC 130 taught by Professor Ranganath during the Spring '10 term at UC Davis.

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PSC 131 Study Guide - Class Notes for PSC131 (Midterm 1)...

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