Nature 363, 546 - 549 (10 June 1993); doi:10.1038/363546a0

The Nagel anomaloscope and seasonal variation of colour vision

G. Jordan & J. D. Mollon

Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK

IN 1948 the German physicist, Manfred Richter, reported that colour vision has a seasonal variation^1,2. For four colour-normal subjects, he found a sinusoidal variation in the proportion of red and green required to match a monochromatic yellow, the equation known as the 'Rayleigh match'³. In summer, subjects required more red in their mixture. The measurements were made with the Nagel anomaloscope, an instrument introduced in 1907^4,5 and which today, essentially unchanged, remains the definitive clinical instrument for classifying the many phenotypic variations in colour vision. The variation that Richter recorded in the red–green ratio was large (three Nagel units), and it now takes on fresh interest because it is comparable in size to the difference in Nagel settings later reported between normal observers of different genetic types^6,7. We have been able to replicate Richter's result, but report here that it is almost certainly instrumental: the Nagel anomaloscope proves to be very sensitive to ambient temperature.

References

1.	Richter, M. Z. wíss. Photogr. Photophy. Photoch. 43, 209−237 (1948).
2.	Richter, M. Klin. Mon. Augenheilkunde 119, 561−575 (1951). | ChemPort |
3.	Rayleigh, L. Nature 25, 64−66 (1881).
4.	Nagel, W. A. Z. Augenheilkunde 18, 201−222 (1907).
5.	Nagel, W. in Handbuch der Physiologischen Methodik (ed. Tigerstedt, R.) (Hirzel, Leipzig. 1909).
6.	Waaler, G. H. M. Nature 215, 406 (1967). | PubMed | ChemPort |
7.	Waaler, G. H. M. Avhandl. Det Norske Videnskaps-Akad. Oslo I Mat.-Naturv. Klasse. Ny Serie, No. 9, 1−25 (1967).
8.	Pokorny, J., Smith, V. C., Verriest, G. & Pinckers, A. J. L. G. Congenital and Acquired Color Vision Defects (Grune & Stratton, New York, 1979).
9.	De Vries, H. Experientia 4, 357 (1948).
10.	Knowles, A. Vision Res. 20, 475−485 (1980). | Article | PubMed | ChemPort |
11.	Moreland, J. D. in Colour Vision Deficiencies II (ed. Verriest, G.) 14−18 (Karger, Basel, 1974). | ChemPort |
12.	Merton, T. R. Proc. R. Soc. 113, 704−708 (1927).
13.	Winderickx, J. et al. Nature Genet. 1, 251−255 (1992). | Article | PubMed | ISI | ChemPort |
14.	Köllner, H. Arch. Augenheilkunde 78, 302−335 (1915).
15.	Jordan, G. Polymorphism of Normal Colour Vision in Humans (University of Cambridge, Cambridge, 1992).
16.	Heinsius, E. Farbsinnstörungen und ihre Prüfung in der Praxis (Ferdinand Enke, Stuttgart, 1973).