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Coplanar ratio hyphothesis
Coplanar ratio hyphothesis An hypothesis by Gilchrist in which the visual system does not use retinal contrasts to determine relative lightnesses but uses depth information to determine which regions are at the same depth (coplanar) and uses their contrasts to deteremine the lightness perceived. This hypothesis has come under recent attack.
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Retinal
Light-absorbing portion of rhodopsin. The absorption of light causes retinal to change from 11-cis to 11-trans configuration
Lightness
The perception of reflectance. Related to the perception of an object's surface.
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Copley Hospital
The Copley Hospital is a hospital in Morristown, Vermont, United States.
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Color opponent channel
Pathway that begins with the midget (parvo) ganglion cells in the retina and terminates within the parvocellular layer of the LGN. Conduction slower than that of Magnocellular Pathway.
Complex cells
Cells in the primary visual cortex (V1) that responding either to an edge, a bar or a slit stimulus of a particular orientation falling anywhere in its receptive field. The exact location of the stimulus within the receptive field is not as critical. Have receptive fields longer than those of simple cells. The cell behaves non-linearly, responding to a drifting cosine grating with a uniform increase in activity with no sinusiodal modulcation (i.e. insensitive to phase). For a historical perspective see Simple Cells.
Concentric field
A receptive field divided into an inner circular region and an outer ring-shaped region. Light falling in each of the two regions has opposite effects on the response of the cell.
Cone opsin
Light absorbing molecule in cone cells.
Contrast sensitivity function
The reciprocal of the threshold contrast required to obtain a criterion response from a cell or a human subject as a function of spatial frequency. Falls off in sensitivity as the spatial frequency of the test pattern increases.
Coplanar ratio hyphothesis
Correspondence problem
In Stereopsis: the challenge of matching elements in one eye with elements in another eye. Also known as the Matching Problem. In Motion:
the challenge of matching moving elements in one frame with elements in a succeeding frame (especially true of random dot cinematograms).
Corticaltectal pathway
Pathway from the cortex to the superior colliculi.
Cortical magnification factor
Defined as millimeters of cortex per degree of visual angle.
CPD
Cycles per degree of visual angle. The human limit is about 30cpd in the fovea for an individual with 20/20 vision.
Critical flicker frequency (CFF)
The frequency of flicker where the alternating levels of brightness are seen as a single level. The frequency is dependent on brightness levels and retinal location.
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