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Law of Specific Nerve Energies
Statement that each nerve always conveys the same kind of information to the brain
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Pupil
Where light enters the eye
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Retina
Rear surface of the eye which in lined with receptors
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Bipolar Cells
Neuron in the retina that receives input directly from the receptors
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Ganglion Cells
Neuron in the retina that receives input from the bipolar cells
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Optic Nerve
Bundle of axons that travel from the ganglion cells of the retina to the brain
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Blind Spot
Has no receptors, the point where the optic nerve exits the back of the eye
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Fovea
Tiny area in the center of the retina specialized for acute, detailed vision
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Rods
- Respond to faint light
- Found in periphery of the retina
- Outnumber cones 20:1
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Cones
- Abundanct in/around fovea
- Useful in bright light, essential for color vision
- Provide 90% of brain input
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Photo-pigments
Chemical that releases energy when struck by light
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Yem-Helmholtz Theory
We perceive color through the relative rates of response by 3 kinds of cones each sensitive to different sets of wavelengths
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Opponent-Process Theory
We perceive color in terms of oppsites
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Color Constancy
The ability to recognize colors despite changes in lighting
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Retinex Theory
- Edwin Land
- Cortext compares info from various parts of the retina to determine the brightness and color of each area
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Horizontal Cell
Cell that receives input from receptors and delivers inhibitory input to bipolar cells
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Lateral Geniculate Nucleus
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Lateral Inhibition
- Retina's way of sharpening contrasts to emphasize the borders of objects
- Reduction of activity in one neuron by activity in neighboring neurons
- When light falls on a surface, bipolars inside are more excited than outside
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Receptive field
Part of the visual field to which any one neuron responds
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Parvocellular Neurons
Small-celled neuron of the visual system that is sensitive to color differences and visual detailsin its small visual field
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Magnocellular Neurons
Large-celled neuron of the visual system that is sentivie to changing or moving stimuli in a relatively large visual field
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Koniocellular Neurons
Ganglion cells located throughout the retina
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Primary Visual Cortex, V1
Area of cortex responsible for the first stage of visual processing
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Secondary Visual Cortex, V2
Area of visual cortex responsible for the 2nd stage of visual processing
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Ventral stream
Visual paths in the temporal cortex, sometimes known as the "what" pathway
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Simple Cell
Type of visual cortex cell that has fixed excitatory and inhibitory zones in it's receptive field
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Complex Cells
Cell type of visual cortex that responds best to a light stimuluus of a particular shape antwhere in its recpetive field
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End-Stopped, Hypercomplex Cell
Of visual cortex that responds to stimuli of a precisely limited type, anywhere in a large receptive field with a strong inhibitory field at one end of its field
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Feature Detectors
Neuron whose recpetors indicate the presence of a particular feature
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Inferior Temportal Cortex
Portion of the cortex where neurons are highly senstivie to complex aspects of the shape of visual stimuli within very large receptive fields
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Shape Constancy
Ability to perceive a shape of an object despite the movement or rotation of the object
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Visual agnosia
Impaired ability to identify visual objects despite otherwise satisfactory vision
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Prosopagnosia
Impaired ability to recognize or identify faces
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Motion Blindness
Impaired ability to perceive the direction or speed of movement, despite otherwise good vision
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Binocular Input
Stimulation from both eyes
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Sensitive Period
Time early in development during which some events has a strong lasting effect (presence of a hormone)
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Retinal Disparity
Discrepancy between what the left eye sees and what the right eyye sees
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Strabismus
Condition in which the two eyes point in different directions
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Astigmatism
Blurring vision for lines in one direction ecause of the nonspherical shape of the eye
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