The science of psychology (Kap 5)

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• sensation the stimulus detection process by which our sense organs respond to and translte environtal stimuli into nerve impulses that are sent to the brain
• perception making ´sense´ of what our senses tell us; it is the active process of organizing this stimulus input and giving it meaning
• psychophysics studies the relationship between physical characteristics of stimuli and sensory capabilities
• absolute threshold the lowest intensity at which a stimulus can be detected 50% of the time
• decision criterion a standard of how certain someone must be that a stimulus is present before they will say they can detect it
• signal detection theory concerned with the factors that influence sensory judgements
• difference threshold defined as the smallest difference between two stimuli that people can perceive 50 % of the time
• webers law states that the difference threshold is directly proportional to the magnitude of the stimulus with which the comparison is being made
• sensory adaptation the dimishing sensitivity to an unchanging stimulus
• sensory transduction the process whereby the characteristics of a stimulus are converted into nerve impulses
• dark adaptation the progressive improvement in brightness sensitivity that occurs over time under conditons of low illumitation
• gustation sense of taste
• olfaction sense of smell
• taste buds small bodies containing taste receptor cells concentrated along the tip, edges and back surface of the tounge
• bottom-up processing individual elements of a stimulus are analysed and then combined to form a unified perception
• top-down processing sensory information is interpreted in light of existing knowlegde, concepts, ideas and expectations
• figure-ground relations our tendency to organize stimuli into a central or foreground figure and a background
• gestalt laws of perceptual organization similarity, proximity, closure and continuity
• perceptual schema a mental representation or image containing the critical and distinctive features of a person, object, event or other perceptual phenomenon
• perceptual constancies allow us to recognice familiar stimuli under varying condition
• binocular disparaty each eye sees a slightly different image
• convergence produced by feedback from the muscles that turn your eyes inwards to view a close objects
• stroboscopic movement illusory movement produced when a light is briefly flashed in darkness and then, a few milliseconds later, another light is flashed nearby
• critical periods during which certain kinds of experiences must occur if perceptual abilities and the brain mechanism that underlie them are to develop normally

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