In addition to wavelength, which we percieve as color, light is also characterized by something called polarity. Unlike many other animals, most humans cannot detect the polarity of light with their eyes, unless they know what they’re doing. There’s a phenomenon called Haidinger’s Brush whereby humans can detect polarized light with their eyes. It works in different ways for different people, but for me, if i jerk my head to the right or to the left while looking at polarized light, I see a pale-yellow bow tie shape.
My comptuer monitor at work uses polarized light because it’s an LED display. Any time I have black text on a white background – which is to say, a quite frequently – if I move my head quickly, I see those brushes. Sometimes I forget I’m at work and waggle my head back and forth to see the brushes. I hope nobody’s watching…