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RESEARCH PRODUCT

Wavelength discrimination in the goldfish

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Wavelength discrimination was measured in three goldfish using a behavioral training technique. TheΔλ function has three minima which indicate spectral ranges of high discrimination ability: at 410–420 nm, at 500 nm and at 600–610 nm (Fig. 5). The best discrimination of all was found at 500 nm:Δλ as low as 4 nm. Model computations were performed to find out whether theΔλ function can be explained on the basis of the cone sensitivity functions. The results (Figs. 6 and 7) indicate that the high discrimination ability at 600–610 nm can be explained under the assumption that the long-wave cone mechanism is modified by neural interactions. The high discrimination at 410–420 nm. indicates the existence of an ultraviolet receptor as shown in color mixture experiments reported by Neumeyer (1985).