July15_09 - 7/07/06 Psych 1 Principles of Psychology...

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1 7/07/06 Psych 1 Principles of Psychology Sensation: neural transduction. The conversion of energy from the environment (stimuli) into a pattern of response in the nervous system by receptor cells. Electromagnetic radiation (light) Molecules Air pressure waves Mechanical force (pressure) Perception: Organization, reorganization, contextualization and interpretation of patterns of neural responses. Visual Sensation Stimuli: electromagnetic radiation (emr) with approximately 360 to 750 nm wavelength (shorter than Radio waves and longer than X- rays) i. Wavelength is inversely related to frequency of oscillation, I.e. shorter wavelength = higher frequency. Emr is often described in terms of frequency. Visual Sensation Sensory organ: The Eye Visual Sensation The Eye: 1. Light waves/particles (photons) reflect off of stimuli and pass through the pupil , an adjustable opening. 2. The Iris , a ring of muscle that forms the colored portion of the eye around the pupil, controls the size of the pupil opening. Pupil expands in low light conditions and constricts in high light conditions. 3. The cornea , a stiff transparent structure on the surface of the eye, focuses light through the pupil. 4. After passing through the pupil, light passes through the lens , which adjusts it convexity in order to focus information from stimuli at varying distances from the eye, a process called accommodation . Focusing on closer stimuli requires more convex lens Focusing on further stimuli requires flatter lens Visual Sensation The Eye: 5. Focused light waves/particles (photons) pass through the vitreous humor , jellylike eye filling, then hit the retina , which lies along the inner surface of the back of the eye. 6. Receptor cells in the retina transduce the incoming photons into neural signals.
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2 Visual Sensation The Retina: c Contains two types of specialized photon sensitive neurons: rods and cones . c Is inside out . The rods and cones are furthest from the cornea; They synapse with other layers of cells that are closer to the cornea. Visual Sensation 2. Bipolar neurons synapse onto ganglion neurons. 3. Ganglion neuron axons bundle together and carry information out of the eyeball and into the brain. The place where ganglion cell axons exit the eyeball is called the blind spot, because there are no rods or cones there. The brain fills in the blind spot, as well as other missing/altered input resulting from blood vessels etc. The Retina: Photons stimulate chemical changes in rods and cones, causing them to synapse onto bipolar neurons. Visual Sensation The Visual Pathway: Visual Sensation Color: wavelength and amplitude characteristics of emr correspond to different colors and brightness of light (and sound ). Visual Sensation
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This note was uploaded on 01/13/2010 for the course PSYCH 1 taught by Professor Shimamura during the Summer '08 term at University of California, Berkeley.

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July15_09 - 7/07/06 Psych 1 Principles of Psychology...

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