Ch 4-Sensation and Perception

Ch 4-Sensation and Perception - Chapter 4-Sensation and...

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Chapter 4-Sensation and Perception 9/18/07 Basic Definitions o Sensation : the process by which our sense organs respond to and translate stimuli into nerve impulses sent to the brain o Perception : organizing stimulus input into meaningful patterns Stages of sensation and perception o Stimuli activate sensory receptors o Sensory receptors translate information into nerve impulses o Specialized neurons analyze stimuli features o Stimulus pieces are reconstructed and compared to stimuli in memory o Perception is then consciously experienced Psychophysics o Definition : the study of sensitivity to stimuli o Absolute limits Dimmest light in which we can see objects Softest sound we can hear o Recognizing differences between stimuli Smallest difference in brightness detectable Recognizing differences between tones Stimulus detection o The absolute threshold : the lowest intensity at which a stimulus can be detected 50% of the time Modality Threshold Vision Candle flame at 30 miles on a clear dark night Hearing Tick of a watch under quiet conditions at 20 ft. Taste 1 teaspoon of sugar in 2 gallons of water Smell 1 drop of perfume diffused into the entire volume of a large apartment Touch Wing of a fly or bee falling on your cheek from a distance of 1 cm. Signal detection theory o Decision criterion : a personal standard of certainty before a person will say that they detect a stimulus o Affected by: Whether the individual is conservative or bold Increasing rewards for hits or costs for misses Four possible outcomes for signal detection Stimulus Present Absent Person’s Response “yes” Hit False alarm “no” Miss Correct rejection Subliminal perception o When a subliminal stimulus cannot be perceived consciously but does register in the nervous system o Research results
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Chapter 4-Sensation and Perception 9/18/07 Stimuli above threshold influence behavior much more than subliminal stimuli Subliminal stimuli have stronger effects on attitudes than behavior The difference threshold o The difference threshold (just noticeable difference: JND) is the smallest difference between two stimuli that people can perceive 50% of the time
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Ch 4-Sensation and Perception - Chapter 4-Sensation and...

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