|
| | |
Silent substitution
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.
RELATED TERMS--------------------------------------
Temporal
Having to do with the side of the head.
Cone
One of the two light receiving retinal cells (the other is the rod) that is responsible for daylight vision (e.g., color vision, high visual acuity, bright light vision). The area of the retina that provides central or reading vision, known as the fovea, contains only cones.
Contrast
"Short for ""contrast media."" Contrast media are X-ray dyes used to provide contrast, for example, between blood vessels and other tissue."
SIMILAR TERMS--------------------------------------
Sile Devlet Hastaness
The Sile Devlet Hastaness is a hospital in Istanbul, Turkey.
Silent ischemia
Ischemia not accompanied by chest pain.
PREVIOUS AND NEXT TERMS--------------------------------------
Sensitivity
1. The reciprocal of the minimum stimulus strength required for the stimulus to be detected reliably (1/threshold) May be related to noise and other mechanisms.
2. Physiologically measured sensitivity averaged over many stimulus/response cycles. A measure of gain. Noise free.
Sensitivity control
Adjustment of eye sensitivity to compensate for a change in illumination.
Sensory fusion
The combining of drawing together of two images which fall on different points in the two retinas without changing the vergence of the two eyes.
Short-Sightedness
See Myopia.
Short-term visual store
Visual memory not affected by masking, not in anatomical coordinates, limited in capacity. Less is retained from complex images than simple images.
Silent substitution
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
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.
We thank you for using the Health Dictionary to search for Silent substitution. If you have a better definition for Silent substitution than the one presented here, please let us know by making use of the suggest a term option. This definition of Silent substitution may be disputed by other professionals. Our attempt is to provide easy definitions on Silent substitution and any other medical topic for the public at large.This dictionary contains 25007 terms. |
|
|
