Ich dachte ich hätte alles schon an optischen Täuschungen gesehen, aber das kannte ich noch nicht. Mehr noch haltet mal die blaue Perle im Haar zu und schaut euch dann einige Sekunden lang das ‘blaue’ Auge an.

Hier die Erklärung, in Englisch:

The girl’s right eye only looks the same as the turquoise hair clip because of the reddish context. Part of the process of seeing color is that three different kinds of photoreceptors in the eye are tuned to three overlapping families of color: red, green and blue (which are activated by visible light of long, medium and short wavelengths). These signals are then instantaneously compared with signals from nearby regions in the same scene. As the signals are passed along to higher and higher processing centers in the brain, they continue to be compared with larger and larger swaths of the surrounding scene. This “opponent process,” as scientists call it, means that color and brightness are always relative.

via geekosystem