#QOTO: How, or whether, would the human eye perceive a shift in phase (angle) of electromagnetic waves in the visible fraction of the spectrum?
Like, change in frequency is perceived as change in color; change in amplitude is perceived as change in intensity of light; would the human eye be able to detect a phase shift? Are eyes of any other animal(s) able to detect phase change?
Some animals can see polarisation of light, but I don't think phase is a meaningful property in this context. If I just draw a sine wave on a piece of grid paper, its phase is undefined until I add axes showing where the y=0 crossing is in relation to the x=0 crossing.
Further, we very rarely see pure monochromatic light; we are mostly exposed to unsaturated tones composed of anywhere from several to infinitely many frequencies at varying intensities. We can't even tell what frequencies a white light comprises without special instruments (this is why we can substitute LED or CFL lighting for incandescent, despite having a very different spectra).
