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Perception (from the Latin perceptio, percipio ) is the organization, identification and interpretation of sensory information in order to represent and understand the environment. [ 1 ] All perception involves signals in the nervous system , which in turn result from physical stimulation of the sense organs. [ 2 ] For example, vision involves light striking the retinas of the eyes, smell is mediated by odor molecules and hearing involves pressure waves . Perception is not the passive receipt of these signals, but can be shaped by learning , memory and expectation . [ 3 ] [ 4 ] Perception involves these "top-down" effects as well as the "bottom-up" process of processing sensory input. [ 4 ] The "bottom-up" processing is basically low-level information that's used to build up higher-level information (i.e. - shapes for object recognition).
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