After adaptation to vertical orange and black stripes, alternating every 15 s with identical but horizontal black and blue stripes, black and white stripes appear:

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Quizplus · Accepted Answer

This is due to the phenomenon of color aftereffects, where the visual system adapts to the colors it has been exposed to. After adapting to orange and black, and blue and black stripes, the complementary colors (blue/green for orange and orange for blue) are perceived when viewing black and white stripes. The orientation of the stripes affects which adaptation is triggered.

After Adaptation to Vertical Orange and Black Stripes, Alternating Every