Influence of shadow quality on color appearance.

Shadows of skylight quality and of daylight quality were cast upon various test samples. The color appearance of a test sample, both as shadowed and as unshadowed, was matched by adjusting the field of a visual colorimeter. Only the skylight shadow evoked any trend in hue, and this was toward the blue; but both shadows produced systematic losses in saturation and lightness. Still none of these perceptual changes was as great as the corresponding colorimetric change in the test stimulus would suggest; in other words, considerable color constancy was associated with both shadows. The difference in effect between the two kinds of shadows was appreciable as evaluated in Munsell hue but seemed almost negligible as regards value and chroma. These results refer to the attention-directed experimental observations; more casual viewing presumably would result in more constancy effect and even less differential effect.