6th lecture - Sensation and Perception Sensation: stimulus...

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Sensation and Perception
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Sensation: stimulus detection process where our sense organs respond to and translate stimuli into nerve impulses sent to the brain. Perception: active process of organizing stimulus input and giving it meaning
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Stimulus Detection: How intense does a stimulus need to be for us to recognize its presence? Absolute Threshold: the lowest intensity at which a stimulus can be detected at least 50% of the time.
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Absolute Threshold Sense Modality Absolute Threshold vision candle flame at 30 miles on a clear night hearing watch ticking at 20 feet in a quiet room taste 1 tsp sugar in 2 gallons of h20 smell 1 drop of perfume in 6(3) room apt touch wing of bee on cheek dropped from 1 cm
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Signal Detection Theory: various factors influence our sensory judgment; often involves a process of decisions in addition to sensation Difference Threshold: the smallest difference between two stimuli that people can perceive 50% of the time
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Weber’s Law: the difference threshold is directly proportional to the magnitude of the stimulus to which the comparison is being made. e..g. Value for weight is 1/50…Backpack example Fechner’s Law: larger and larger increases in physical energy are required to produce equal increases in perception e.g. light bulb example
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Just noticeable difference: the smallest difference in which you can detect a difference threshold Sensory adaptation (habituation): over time neurons decrease activity in response to a constant stimulus
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Sensory Systems: Vision The normal stimulus for vision is electromagnetic energy or light waves Light waves are measured in nanometers Our visual system is sensitive to wavelengths extending from ~700 nanometers (red) to ~ 400 nanometers (blue-violet)
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ROY G BIV: (higher to lower wave lengths)
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The Human Eye
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Light waves enter the eye through the cornea The pupil: behind the cornea, the pupil adjusts to control the amount of light that enters the eye The iris: the pupil’s size is controlled by muscles in the colored iris that surrounds the pupil
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Low levels of light cause the pupils to dilate: allows more light and improves optical clarity Behind the pupil is the lens
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6th lecture - Sensation and Perception Sensation: stimulus...

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