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Biomedical subjects

D Carden

Publications and source records attributed to D Carden.

24 records · Page 2Linked to original sources
PubMed1977

Direct readout of spectral sensitivity for clinical and research purposes.

The application of spectral sensitivity measurements to clinical problems has been limited by the complexity of calculating the corrections for nonlinearity and non-neutrality of the neutral wedge and for the quantum intensity of the test beam. Asimple electronic system is described which performs all these calculations automatically, as the subject makes the sensitivity setting, and records the sensitivity on an XY plotter. A range of 5 log units is covered with an accuracy of 0.05 log units.

Color Perception Tests↗
PubMed1976

Luminance and opponent-color contributions to visual detection and adaptation and to temporal and spatial integration.

We show how the processes of visual detection and of temporal and spatial summation may be analyzed in terms of parallel luminance (achromatic) and opponent-color systems; a test flash is detected if it exceeds the threshold of either system. The spectral sensitivity of the luminance system may be determined by a flicker method, and has a single broad peak near 555 nm; the spectral sensitivity of the opponent-color system corresponds to the color recognition threshold, and has three peaks at about 440, 530, and 600 nm (on a white background). The temporal and spatial integration of the opponent-color system are generally greater than for the luminance system; further, a white background selectively depresses the sensitivity of the luminance system relative to the opponent-color system. Thus relatively large (1 degree) and long (200 msec) spectral test flashes on a white background are detected by the opponent-color system except near 570 nm; the contribution of the luminance system becomes more prominent if the size or duration of the test flash is reduced, or if the white background is extinguished. The present analysis is discussed in relation to Stiles' model of independent eta mechanisms.

Adult↗