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Unformatted text preview: Chapter 7: Smell, Taste, Pain, Hearing, and Psychophysics Pg. 233-238 Sensation the basic processes by which sensory organs and the nervous system respond to stimuli in the environment and to the elementary psychological experiences that result from those processes Perception organizing of sensory information within the brain and the meaningful interpretations extracted from it Overview of Sensory Processes Physical stimulus >> physiological response >> sensory experience Raw sensory experience is not assessed but the individuals ability to use that experience to guide a behavior The Basic Anatomy of the Human Senses o Receptors structures that respond to physical stimulus by producing electrical changes that can initiate neural impulses o Sensory neurons carry neural impulses from the receptors to the central nervous system Sensory-specific pathways carry these impulses Sensory areas in the cerebral cortex analyze this neural input Every sensory experience is a product of brain activity Transduction and Coding: Preserving Information about the Stimulus o Transduction the process by which a receptor cell produces an electrical change in response to a physical stimulus Membrane of receptor cell becomes more permeable to certain particles when the appropriate type of stimulus energy acts on the cell Receptor potential electrical change as a result of this particle movement o Energy variation of stimulus energy Quantitative variation amount or intensity of energy Qualitative variation kind of energy o Coding preservation of stimulus energy information that is sent to brain Sensory Adaptation: Responding to Change More Than to Steady States o In the absence of stimulation a sensory system becomes temporarily more sensitive; in the presence of stimulation it temporarily becomes less sensitive o Receptor cells mediate; if stimulus remains, rate of action potentials decrease Pg. 263-271 Psychophysics study of the relationship between the physical characteristic of a stimulus and the sensory experience that it produces Detecting Weak Stimuli and Small Difference The Absolute Threshold, and Why It is Not Absolute o Absolute threshold faintest detectable stimulus of any given type o Determined by presenting the stimulus many times at various low intensities and each time asking the person if detect or not o Very arbitrary nature Signal Detection as a Decision-Making Task o Response bias, the tendency to favor a particular response when unsure, may mask true aspect of absolute threshold o Hits, misses, false alarms, and correct rejection; by comparing proportion of hits to false alarms, can derive a measure of sensitivity independent of response bias called d The Difference Threshold and Webers Law o Difference threshold ( just-noticeable difference jnd) minimum difference that must exist between two stimuli to detect them as different in 50% of the trials...
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This note was uploaded on 04/02/2008 for the course PSYCH 1 taught by Professor Shimamura during the Fall '08 term at University of California, Berkeley.
- Fall '08