P Lec Notes 092310 - Psych Lecture Notes 09/23/10 Sensation...

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Psych Lecture Notes 09/23/10 Sensation and Perception 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 and giving it meaning 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. 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 water smell 1 drop of perfume in 6 (3) room apartment touch wing of bee on cheek dropped from 1 cm -Signal Detection theory: various factors influence our sensory judgment; often involves a process of decision in addition to sensation -Difference Threshold: the smallest difference between two stimuli that people can perceive 50% of the time. -Weber's Law: the difference threshold is directly proportional to the magnitude of the stimulus to which the comparison is being made. Ex) 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. Ex) light bulb. Comparative between 0 to 25 watts and 25 to 50. -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. -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 -Low levels of light cause the pupils to dilate: allows more light in and improves optical clarity -Lens behind the pupil; becomes thinner to focus on distant objects, become thicker to focus on
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P Lec Notes 092310 - Psych Lecture Notes 09/23/10 Sensation...

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