Psych Ch5 Outline

Psych Ch5 Outline - 5 Sensation a Eye Stimulus Structure...

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5) Sensation )a )i Transduction process by which a sense organ transforms physical energy into electrical signals that become neural impulses that are sent to the brain for processing. )ii Adaptation process in which continuous sensory stimulation results in a decrease of activity from the appropriate organ. )iii Sensations outcome of the brain’s initial processing of electrical signals from sensory receptors. In themselves, they are meaningless pieces of info. )iv Perceptions outcome of the brain’s next step, which is to combine basic sensations into meaningful experiences. )v Visible spectrum segment of electromagnetic energy whose waves can be seen by the naked eye because they are of the right wavelength to stimulate the eyes. ()1 Wavelength is between 400 (violet) and 700 (red) nanometers. )vi Process of seeing: ()1 Light waves reflect off an object into the eye. ()2 The eye flips the image of the object and the brain flips it back. ()3 Cornea rounded, transparent covering over the front of the eye that focuses waves into a narrower beam. ()4 Pupil rounded opening of eye that allows light waves to enter eye’s interior. ()5 Iris circular muscle that surrounds the pupil and r egulates the flow of light into the eye. ()a In dim light the iris relaxes, letting in more light. ()b In bright light the iris constricts, letting in less light. ()6 Lens transparent, oval structure whose curved surface bends and focuses light waves into even a narrower beam. The shape of the lens is altered by the muscles attached to it. ()a Light waves from distant objects need less bending and focusing, so muscles contract to make the lens less curved. ()b Light waves from close objects need more focusing, so the muscles relax to allow the lens to be more curved. ()7 Retina thin film containing three layers of cells located at the back of the eyeball. The third and farthest layer contains light sensitive cells called photoreceptors. ()a Light waves are focused on retina. The retina contains two types of photoreceptors. ()b Rods photoreceptors that contain a single chemical called rhodopsin, which is activated by small amounts of light. Because the rods are extremely light sensitive, they allow the brain to see dim light, but only to see black, white, and shades of gray. ()i There are 60 million rods in the periphery of the retina. ()ii There are multiple rods connected to neighboring ganglion cells.
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()c Cones photoreceptors that contain three chemicals called opsins, which are activated in bright light and allow the brain to see color. ()i There are three million cones in part of retina called the fovea. ()ii Unlike rods, each cone is
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This note was uploaded on 04/07/2008 for the course PSYCH 2140 taught by Professor Edelman during the Fall '08 term at Cornell.

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Psych Ch5 Outline - 5 Sensation a Eye Stimulus Structure...

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