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This Article Full Text Full Text (PDF) All Versions of this Article: 566/1/61    most recent jphysiol.2005.084046v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stockman, A. Articles by Montag, E. D Search for Related Content PubMed PubMed Citation Articles by Stockman, A. Articles by Montag, E. D

¹ Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
² Department of Psychology, University of California San Diego, La Jolla, CA 92093-0109, USA
³ Rochester Institute of Technology, Center for Imaging Science, Munsell Color Science Laboratory, 54 Lomb Memorial Drive, Rochester, NY 14623-5604, USA

The nature of the inputs to achromatic luminance flicker perception was explored psychophysically by measuring middle- (M-) and long-wavelength-sensitive (L-) cone modulation sensitivities, M- and L-cone phase delays, and spectral sensitivities as a function of temporal frequency. Under intense long-wavelength adaptation, the existence of multiple luminance inputs was revealed by substantial frequency-dependent changes in all three types of measure. Fast (f) and slow (s) M-cone input signals of the same polarity (+sM and +fM) sum at low frequencies, but then destructively interfere near 16 Hz because of the delay between them. In contrast, fast and slow L-cone input signals of opposite polarity (–sL and +fL) cancel at low frequencies, but then constructively interfere near 16 Hz. Although these slow, spectrally opponent luminance inputs (+sM and –sL) would usually be characterized as chromatic, and the fast, non-opponent inputs (+fM and +fL) as achromatic, both contribute to flicker photometric nulls without producing visible colour variation. Although its output produces an achromatic percept, the luminance channel has slow, spectrally opponent inputs in addition to the expected non-opponent ones. Consequently, it is not possible in general to silence this channel with pairs of ‘equiluminant’ alternating stimuli, since stimuli equated for the non-opponent luminance mechanism (+fM and +fL) may still generate spectrally opponent signals (+sM and +sL).

(Received 28 January 2005; accepted after revision 25 April 2005; first published online 28 April 2005)
Corresponding author A. Stockman: Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK. Email: a.stockman{at}ucl.ac.uk

This article has been cited by other articles:

				A. Stockman and D. J Plummer Spectrally opponent inputs to the human luminance pathway: slow +L and -M cone inputs revealed by low to moderate long-wavelength adaptation J. Physiol., July 1, 2005; 566(1): 77 - 91. [Abstract] [Full Text] [PDF]