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Sensation and Perception (A)

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Sensation
The stimulation of sense organs.
Perception
The selection, organization, and interpretation of sensory input.
Psychophysics
The study of how physical stimuli are translated into psychological experience.
Absolute Threshold
For a specific type of sensory input is the minimum stimulus intensity that an organism can detect.
Just Noticeable Difference (JND)
The smallest difference in stimulus intensity that a specific sense can detect.
Weber's Law
States that the size of a just noticeable difference is a constant proportion of the size of the initial stimulus.
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.
Subliminal Perception
The registration of sensory input without conscious awareness.
Sensory Adaptation
A gradual decline in sensitivity to prolonged stimulation.
Lens
The transparent eye structure that focuses the light rays falling on the retina.
Nearsightedness
Closes objects are seen clearly but distant objects appear blurry.
Farsightedness
Distant objects are seen clearly but close objects appear blurry.
Pupil
The opening in the center of the iris that permits light to pass into the rear chamber of the eye.
Retina
The neural tissue lining the inside back surface of the eye; it absorbs light , processes images, and sends visual information to the brain.
Optic Disk
A hole in the retina where the optic nerve fibers exit the eye.
Cones
Specializes visual receptors that play a key role in daylight vision and colour vision.
Fovea
A tiny spot in the center of the retina that contains only cones; visual acuilty is greatest at this spot.
Rods
Specialized visual receptors that play a key role in night vision and peripheral vision.
Dark Adaptation
The process in which the eyes become more sensitive to light in low illumination.
Light Adaptation
The process whereby the eyes become less sensitive to light in high illumination.
Receptive Field Of A Visual Cell
The retinal area that, when stimulated, affects the firing of that cell.
Lateral Antagonism
Occurs when neural activity in a cell opposes activity in surrounding cells.
Optic Chiasm
The point at which the optic nerve from the inside half of each eye cross over and project to the opposite half of the brain.
Parallel Processing
Involves simultaneously extracting different kinds of information from the same input.
Feature Detectors
Neurons that respond selectively to very specific features of more complex stimuli.
Subtractive Colour Mixing
Removing some wavelengths of light, leaving less light than was originally there.
Trichromatic Theory of Colour Vision
That the human eye has three types of receptors with differing sensitives to different light wavelengths.
Colour Blindness
A variety of deficiencies in the ability to to distinguish among colours.
Complementary Colours
Pairs of colours that produce gray tones when mixed together.
Additive Colour Mixing
superimposing lights, putting more light in the mixture than exists in any one light by itself.
Opponent Process Theory of Colour Vision
Colour perception depends on receptors that make antagonistic responses to three pairs of colours.
Inattentional Blindness
The failure to see visible objects or events because one's attention is focused elsewhere.