Chromatic response mechanisms in the human fovea as measured by threshold spectral sensitivity

Threshold sensitivity was measured with 40-degree surrounds of 5.3 and 800 trolands of white, and 509, 580, and 690 mmicro spectral light. With the brighter white surround there appeared peaks at 550, and 570 and a shoulder at 600 mmicro. These were selectively eliminated by the spectral surrounds.