chapter 6 notes

chapter 6 notes - CHAPTER 6 Vision Sensory receptors=...

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CHAPTER 6: Vision Sensory receptors= specialized neurons that detect particular physical events. Sensory tranduction= process by which sensory stimuli are transduced into receptor potentials. Receptor potentials: slow, graded electrical potential made by receptor in response to stimuli. The stimulus: electromagnetic radiation w/ wavelength btw 380-760 nanometers is visible to humans. Perceived color of light is determined by 3 dimensions: hue (dominant wavelength), saturation (relative purity of light), and brightness (intensity). Light travels at constant speed of approx 300, 000 km/second. If all radiation is of one wavelength, perceived color is pure/fully saturated (black). If the radiation contains all wavelengths, it produces no sensation of hue (white). Anatomy of visual system: Eyes: suspended in the orbits - bony pockets in front of skull; held in place and moved by 6 extraocular muscles attach to tough, white outer coat of the eye called the sclera . Eyes make 3 types of movements- vergence, saccadic, and pursuit movements: Vergence: cooperative movements; ensures image of object falls on same parts of both eyes. Saccadic: rapid, jerky movement of eyes in scanning a visual scene. Pursuit: movement that eyes make to maintain image of moving objects on the fovea. The lens, right behind iris, contains series of transparent, onionlike layers; its shape can be altered by contraction of the ciliary muscles. This lets the eye focus images of near or distant objects on retina= accommodation process. After lens light goes through vitreous humor, then falls on retina – interior lining of back of eye. Retina The receptor cells (rods and cones= photoreceptors) are located in the retina. Retina contains approx 120 million rods and 6 million cones; but cones provide the most info. The fovea: central region of retina; mediates our most acute vision; contains only cones. Cones are responsible for color vision- our ability to discriminate light of different wavelengths.
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This note was uploaded on 12/18/2011 for the course PSYC 211 taught by Professor Yogitachudasama during the Winter '09 term at McGill.

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chapter 6 notes - CHAPTER 6 Vision Sensory receptors=...

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