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Science 21 April 1989:
Vol. 244. no. 4902, pp. 354 - 356
DOI: 10.1126/science.2711186
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Articles

Science, Vol 244, Issue 4902, 354-356
Copyright © 1989 by American Association for the Advancement of Science

articles

The incremental threshold of the rod visual system and Weber's law

LT Sharpe, C Fach, K Nordby, and A Stockman

Neurologische Universitatsklinik, Freiburg im Breisgau, Federal Republic of Germany.

The incremental threshold of the isolated rod visual system is believed, under certain conditions, to obey Weber's law (that is, to increase in direct proportion to the intensity of the background). This relation was tested at several background wavelengths, over an intensity range for which the target was seen only by the rods. Although the slope on long-wavelength background approximates unity (that is, Weber's law on log-log coordinates), it averages less than 0.8 on short- and middle-wavelength backgrounds. This is the same value as that found for the thresholds of a typical, complete achromat--who lacks cone vision--regardless of background wavelength. These results force the conclusion that Weber's law for incremental threshold detection is achieved not by the rods alone but only by the rods acting together with the cones.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Gap-Junctional Coupling and Absolute Sensitivity of Photoreceptors in Macaque Retina.
E. P. Hornstein, J. Verweij, P. H. Li, and J. L. Schnapf (2005)
J. Neurosci. 25, 11201-11209
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