Table 1.

Visual contrasts of all conditioned patterns.

	Mean RGB value	Grayscale value	Visual contrast	Light irradiance (μW/cm2)
Grayscale 0	(0, 0, 0)	0	−128	9.9
Grayscale 32	(32, 32, 32)	32	−96	28.9
Grayscale 43	(43, 43, 43)	43	−85	30.8
Grayscale 64	(64, 64, 64)	64	−64	36.9
Grayscale 96	(96, 96, 96)	96	−32	53.7
Red-black checkerboard	(128, 0, 0)	43	−85	40.7
White-black checkerboard	(128, 128, 128)	128	0	102.4
Background (grayscale 128)	(128, 128, 128)	128	0	108.1

In the table, the first column lists all conditioned patterns used in the experiments. Visual contrast = grayscale value of conditioned pattern—grayscale value of background (128).