What is the Relationship Between Sensation and Perception? -Perception brings meaning to sensation, so perception produces an interpretation of the world, not a perfect representation of it. Percept: The meaningful product of perception?often an image that has been associated with concepts, memories of events, emotions, and motives. Perceptual Processing: Finding Meaning in Sensation Feature detectors: Cells in the cortex that specialize in extracting certain features of a stimulus. Binding problem: Refers to the process used by the brain to combine (or ?bind?) the results of many sensory operations into a single percept. This occurs, for example, when sensations of color, shape, boundary, and texture are combined to produce the percept of a person?s face. No one knows exactly how the brain does this. Thus, the binding problem is one of the major unsolved mysteries in psychology. Top-down processing: Perceptual analysis that emphasizes the perceiver?s expectations, concept memories, and other cognitive factors, rather than being driven by the characteristics of the stimulus. ?Top? refers to a mental set in the brain?which stands at the ?top? of the perceptual processing system. Bottom-up processing: Perceptual analysis that emphasizes characteristics of the stimulus, rather than our concepts and expectations. ?Bottom? refers to the stimulus, which occurs at step one of perceptual processing. Perceptual Constancy: The ability to recognize the same object as remaining ?constant? under different conditions, such as changes in illumination, distance, or location. Change blindness: A perceptual failure to notice changes occurring in one?s visual field. Perceptual Ambiguity and Distortion Illusion: You have experienced an illusion when you have a demonstrably incorrect perception of a stimulus pattern, especially one that also fools others who are observing the same stimulus. (If no one else sees it the way you do, you could be having a hallucination.) Ambiguous figures: Images that are capable of more than one interpretation. There is no ?right? way to see an ambiguous figure. Theoretical Explanations for Perception Gestalt Psychology: From a German word that means ?whole? or ?form? or ?configuration?. (A Gestalt is also a percept.) The Gestalt psychologists believed that much of perception is shaped by innate factors built into the brain. Figure: The part of a pattern that commands attention. The figure stands out against the ground. Ground: The part of a pattern that does not command attention; the background. Closure: The Gestalt principle that identifies tendencies to fill in gaps in figures and to see incomplete figures as complete. Law of Perceptual Grouping: The Gestalt principles of similarity, proximity, continuity, and common fate. These ?laws? suggest how our brains prefer to group stimulus elements together to form a percept (Gestalt). Law of similarity: The Gestalt principle that we tend to group similar objects together in our perceptions. Law of proximity: The Gestalt principle that we tend to group objects together when they are near each other. Law of continuity: The Gestalt principle that we prefer perceptions of connected and continuous figures to disconnected and disjointed ones. Law of common fate: The Gestalt principle that we tend to group similar objects together that share a common motion or destination. Law of Prägnanz: The most general Gestalt principle, which states that the simplest organization, requiring he least cognitive effort, will emerge as the figure. Prägnanz shares a common root with pregnant, and so it carries the idea of a ?fully developed figure.? That is, our perceptual system prefers to see a fully developed Gestalt, such as a complete circle?as opposed to a broken circle. Learning-based inference: The view that perception is primarily shaped by learning (or experience), rather than by innate factors. Perceptual set: Readiness to detect a particular stimulus in a given context?as when a person who is afraid interprets an unfamiliar sound as a threat. Binocular cues: Information taken in by both eyes that aids in depth perception, including binocular convergence, and retinal disparity. Monocular cues: Information about depth that relies on the input of just one eye?includes relative size, light and shadow, interposition, relative motion, and atmospheric perspective.
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