Time Course of Color Appearance Under the Abrupt Decrease in Background Luminance

ABSTRACT In daily life, we often encounter an abrupt decrease in background luminance—such as stage lighting changes or display scene transitions. While many studies have explored discrimination sensitivity under such conditions, especially considering adaptation, the effects on color appearance remain less understood. The time course of color appearance across a range from low to high contrast, the abrupt decrease in background luminance, remains insufficiently understood. This study examined the time course of hue and saturation judgments for the chromatic stimuli of 16 hue angles each with four contrast levels following the abrupt decrease in background luminance from 100 to 1 cd/m 2 . Color stimuli were shown at various stimulus onset asynchronies (SOAs). Results showed that hue judgment remained stable regardless of stimulus contrast. Furthermore, additional analyses revealed that hue judgment did not vary substantially across stimulus contrasts. This means that hue judgment is unaffected by the abrupt decrease in background luminance. In contrast, saturation judgment was significantly influenced: it appeared lower right after the luminance decrease, then gradually increased over time, especially for stimuli with higher contrasts. In summary, the abrupt decrease in background luminance has a substantial impact on saturation.