PSY100H1 Lecture Notes - Dioscorea Alata, Aqueous Humour, Radio Wave

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3 Aug 2010
School
Department
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Psychophysics
-sensation is the stimulation of sense organs
-preception is the selection, organization and interpretation of sensory input
Thresholds
-sensory receptors are tuned to a particular form of energy
-auditory receptors in the ear code for sound pressure changes, not for light
-sensory systems require a minimum amount of energy of activation (absolute threshold)
-Just-noticeable difference (JND): the minimum difference in stimulation that is just
noticeable
-Weber noted that the JND is a fraction of the original stimulus intensity; the fraction
is different from different sense
The Visual System
-the eye detects electromagnetic radiation (light)
-vision is functional
-allows for detection of movement (predator or prey?)
-allows for detection of colour (ripe or spoiled?)
-light detection is useful because
-light travels rapidly (no delay, unlike hearing)
-light travels in a straight line (no distortion)
-light interacts with the surface of objects in the environment (reflected or absorbed)
Transduction of Light
-light travels through the retina to impinge on photoreceptors at the back of the eye
-light bleaches a pigment contained within the photoreceptors
-bleaching leads to a graded receptor potential that eventually produces an action
potential in the ganglion cell
-two types of photoreceptors
1. cones: found in the center of retina (fovea) and are sensitive to fine details and
colour
2. rods: found in periphery of retina and are sensitive to movement but not fine detail
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Details of the Human Eye
Electromagnetic Spectrum
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PSY100H1 Full Course Notes
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PSY100H1 Full Course Notes
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Document Summary

Preception is the selection, organization and interpretation of sensory input. Sensory receptors are tuned to a particular form of energy. Auditory receptors in the ear code for sound pressure changes, not for light. Sensory systems require a minimum amount of energy of activation (absolute threshold) Just-noticeable difference (jnd): the minimum difference in stimulation that is just noticeable. Weber noted that the jnd is a fraction of the original stimulus intensity; the fraction is different from different sense. Allows for detection of movement (predator or prey?) Allows for detection of colour (ripe or spoiled?) Light travels in a straight line (no distortion) Light interacts with the surface of objects in the environment (reflected or absorbed) Light travels through the retina to impinge on photoreceptors at the back of the eye. Light bleaches a pigment contained within the photoreceptors. Bleaching leads to a graded receptor potential that eventually produces an action potential in the ganglion cell.