PSYCH 1 - Psychology Chapter 4 Sensation and Perception...

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Psychology Chapter 4 – Sensation and Perception Hearing The Ear Sound waves strike the tympanic membrane , or eardrum. The vibrations of the eardrum cause three very tiny bones, the malleus , the incus , and the stapes , (literally the hammer, anvil and stirrup) to work to make the sound waves become stronger signals. The stirrup causes the cochlea to vibrate. This vibration displaces hair cells along the basilar membrane within the cochlea. Sensation and Perception Sensation is the conversion of energy from the environment into a pattern of response by the nervous system. Perception is the interpretation of that information. Sensing the World Around Us Stimuli are energies in the environment that affect what we do. Receptors are the specialized cells in our bodies that convert environmental energies into signals for the nervous system. The Detection of Light Light is the stimulus that the visual system is designed to detect. Visible light is just one very small portion of the electromagnetic spectrum, which is the continuum of all the frequencies of radiated energy. The Structure of the Eye Pupil - an adjustable opening in the eye through which light enters. Iris - the structure on the surface of the eye, surrounding the pupil, and containing the muscles that make the pupil dilate or constrict. The cornea is a rigid, transparent structure on the very outer surface of the eyeball. It focuses light by directing it through the pupil. When the light goes through the pupil, it is directed to the lens which directs it through the vitreous humor and it is received in the retina. Common Disorders of Vision Presbyopia develops as humans age because the lens decreases in flexibility, resulting in a reduced ability to focus on nearby objects. Elongated eyeballs cause myopia, so that the person can focus well on nearby objects, but not distant ones. This condition is also called nearsightedness . Flattened eyeballs cause hyperopia, so that the person can focus well on distant objects, but not on nearby ones. This is also called farsightedness . Glaucoma is a condition caused by increased pressure within the eyeball, causing damage to the optic nerve and loss of peripheral vision. A cataract is a disorder in which the lens of the eye becomes cloudy. This disorder is treated by removing and replacing the actual lens with a contact lens. The Visual Receptors
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The retina contains two types of specialized neurons, the rods and the cones. Rods far outnumber cones in the human eye. About 5-10% of the visual receptors in the human retina are cones. The fovea is the center of the human retina, and the location of the highest proportion of cones. Dark Adaptation
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PSYCH 1 - Psychology Chapter 4 Sensation and Perception...

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