CHAPTER 4 - CHAPTER 4 Sensation and Perception Sensation...

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CHAPTER 4: Sensation and Perception Sensation - the stimulation of sense organs (involves the absorption of energy by sensory organs usually light or sound, by the ears or eyes) Perception - is the selection, organization and interpretation of sensory input (involves organizing and translating sensory input into something meaningful) Psychophysics- the study of how physical stimuli are translated into psychological experience - Gustav Fechner : Wanted to know, that for any given stimulus, what was the weakest detectable stimulus… o Threshold - a dividing point between energy levels that do and don not have a detectable effect (central concept to psychophysics) o Absolute Threshold - for a specific type of sensory input is the minimum amount of stimulation that an organism can detect defines the boundaries for organism’s sensory capabilities (the stimulus intensity detected 50% of the time) Just noticeable difference (JND): is the smallest difference in the amount of stimulation that a specific sense can detect - an absolute threshold is simply the just noticeable difference from nothing Weber’s Law : states that the size of a JND is a constant proportion of the size of the initial stimulus - constant proportion = Weber fraction - this law is applied to all the senses - as stimuli increase in magnitude, the JND becomes larger Fechner’s Law : This states that the magnitude of sensory experience is proportional to the number of JND’s that the stimulus causing the experience is above the absolute threshold - constant increments in stimulus produce smaller and smaller increases in the perceived magnitude of sensation - perceptions cant be measured on absolute scales Signal-detection theory : proposes that the detection of stimuli involves decision processes as well as sensory processes, which are both influenced by a variety of factors besides stimulus intensity - your responses will depend in part on the criterion you set for hoe sure you must feel before you react - depends on your expectations and on the consequences Subliminal Perception - the registration of sensory input without conscious awareness (limen = threshold, sub = below below threshold) - messages are likely to be persuasive because people supposedly are defenseless against appeals operating below their threshold of awareness - worthy of experimental investigation Sensory Adaptation - is a gradual decline in sensitivity to prolonged stimulation (factor influencing registration of sensory input) - an automatic, built-in process that keeps people tuned in to the changes rather than the constants in their sensory input - behavioural adaptation that has been sculpted by natural selection
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THE VISUAL SYSTEM People heavily rely on their sense of sight, and they virtually equate it with that is trustworthy (seeing is believing). Vision
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This note was uploaded on 07/17/2011 for the course PSYCH 101 taught by Professor Brandon during the Spring '11 term at Queens Charlotte.

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CHAPTER 4 - CHAPTER 4 Sensation and Perception Sensation...

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