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Stiles-Crawford effect
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Stiles-Crawford effect Light entering the eye through the center of the pupil is more effective than light entering at a peripheral point near the edge of the pupil. This is largely to to the directionally sensitive photoreceptors which are oriented towrad the center of the pupil. This helps to minimize the effect of stray light.
RELATED TERMS--------------------------------------
Pupil
A circular opening in the center of the iris. The size of the pupil changes according to the amount of light present. It is small in sunlight and large in a dark room.
Peripheral
At or near the surface of the body. Located away from the center structure.
SIMILAR TERMS--------------------------------------
Stilbestrol
Stilbestrol is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): diethylstilbestrol.
Stilbetin
Stilbetin is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): diethylstilbestrol.
Still's Disease
A form of Juvenile Chronic Arthritis.
Stillbirth
The death of a baby after 20 weeks' gestation but before birth. Stillbirths are mainly caused by genetic or congenital defects, problems with the umbilical cord or placenta, or a medical condition in the mother.
Stillwater Medical Center
Stillwater Medical Center is a hospital in Stillwater, Oklahoma (USA).
Stilphostrol
Stilphostrol is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): diethylstilbestrol diphosphate.
PREVIOUS AND NEXT TERMS--------------------------------------
Silent substitution
If the action spectra of all photoreceptors types are known, spatial or temporal stimulus patterns can be designed which are invisible to some cone types while producing suprathreshold contrast for others. Thus one can study the range of psychophysical performance that is available for solely one type of cone signal.
Simple cells
One of three cell classifications for cells in the primary visual cortex (V1) proposed by Hubel & Wiesel. Simple cells show rectangular antagonistic on/off zones responding to bars of a particular orientations. They are described as a performing a linear filtering operation followed by a threshold nonlinearity. In a linear system the average response to a drifiting cosine grating will be a cosine at the same frequency. Because of the threshold, response to the negative half-cycles are suppressed.
Size constancy
The fact that the perception of the sizes of objects remains remarkably constant at varying distance despite the fact that the image projected on the retina changes.
Stabilized retinal images
Technique for examining perception without eye movement accompanied by loss of color and contour perception. Demonstrates that movement of an image across the retina is vital for perception.
Stereoscope
Device for creating a 3-D image of a drawn objects. Works by projects two different images of the objects to the eyes.
Stiles-Crawford effect
Stimulus equivalence
If the stimulus controlling behavior is a pattern of light on the retina than an infinite number of images are equivalent in their effects.
Superior colliculus
A nucleus in the midbrain that coordinate visual, somatic and auditory information adjusting movements of the head and eyes towards a stimulus. contains four types of maps, a visual map, a map of the body surface, a map for sound in space and a motor map. Receives inputs from the retina (via the optic tract), the visual cortex, the somatosensory system and auditory systems. Mediates saccadic eye movements. Is the source of two major descending tracts, the tectospinal tract and the tectopontine tract in addition to regions of the brain stem controlling eye movements.
Superior temporal polysensory area (STP)
Area of monkey cortex. Virtually all cells respond to visual stimuli but some also activated by somatosensory and auditory input. Large receptive fields covering most of the visual field with no visuotopic order. Show radial or opponent direction selectivity. Some cells have fields responding to motion either towards the area centralis or away from it. Others show selective responses for object moving in depth, producing either looming or contracting pattern of motion in the field. Seem to be sensitive to information about peripheral optic flow.
Spermatogenesis
Formation of sperm.
Splenomegaly
Enlargement of the spleen.
RELATED TERMS--------------------------------------
Pupil
A circular opening in the center of the iris. The size of the pupil changes according to the amount of light present. It is small in sunlight and large in a dark room.
Peripheral
At or near the surface of the body. Located away from the center structure.
SIMILAR TERMS--------------------------------------
Stilbestrol
Stilbestrol is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): diethylstilbestrol.
Stilbetin
Stilbetin is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): diethylstilbestrol.
Still's Disease
A form of Juvenile Chronic Arthritis.
Stillbirth
The death of a baby after 20 weeks' gestation but before birth. Stillbirths are mainly caused by genetic or congenital defects, problems with the umbilical cord or placenta, or a medical condition in the mother.
Stillwater Medical Center
Stillwater Medical Center is a hospital in Stillwater, Oklahoma (USA).
Stilphostrol
Stilphostrol is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): diethylstilbestrol diphosphate.
PREVIOUS AND NEXT TERMS--------------------------------------
Silent substitution
If the action spectra of all photoreceptors types are known, spatial or temporal stimulus patterns can be designed which are invisible to some cone types while producing suprathreshold contrast for others. Thus one can study the range of psychophysical performance that is available for solely one type of cone signal.
Simple cells
One of three cell classifications for cells in the primary visual cortex (V1) proposed by Hubel & Wiesel. Simple cells show rectangular antagonistic on/off zones responding to bars of a particular orientations. They are described as a performing a linear filtering operation followed by a threshold nonlinearity. In a linear system the average response to a drifiting cosine grating will be a cosine at the same frequency. Because of the threshold, response to the negative half-cycles are suppressed.
Size constancy
The fact that the perception of the sizes of objects remains remarkably constant at varying distance despite the fact that the image projected on the retina changes.
Stabilized retinal images
Technique for examining perception without eye movement accompanied by loss of color and contour perception. Demonstrates that movement of an image across the retina is vital for perception.
Stereoscope
Device for creating a 3-D image of a drawn objects. Works by projects two different images of the objects to the eyes.
Stiles-Crawford effect
Stimulus equivalence
If the stimulus controlling behavior is a pattern of light on the retina than an infinite number of images are equivalent in their effects.
Superior colliculus
A nucleus in the midbrain that coordinate visual, somatic and auditory information adjusting movements of the head and eyes towards a stimulus. contains four types of maps, a visual map, a map of the body surface, a map for sound in space and a motor map. Receives inputs from the retina (via the optic tract), the visual cortex, the somatosensory system and auditory systems. Mediates saccadic eye movements. Is the source of two major descending tracts, the tectospinal tract and the tectopontine tract in addition to regions of the brain stem controlling eye movements.
Superior temporal polysensory area (STP)
Area of monkey cortex. Virtually all cells respond to visual stimuli but some also activated by somatosensory and auditory input. Large receptive fields covering most of the visual field with no visuotopic order. Show radial or opponent direction selectivity. Some cells have fields responding to motion either towards the area centralis or away from it. Others show selective responses for object moving in depth, producing either looming or contracting pattern of motion in the field. Seem to be sensitive to information about peripheral optic flow.
Spermatogenesis
Formation of sperm.
Splenomegaly
Enlargement of the spleen.
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This dictionary contains 19186 terms.
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