Pulfrich
/ˈpʊlfrɪç/ /ˈpʊlfrɪk/noun
Attributive and in the genitive. Used with reference to an optical illusion in which a pendulum appears to describe ellipses instead of a linear arc when viewed with one eye covered with a dark filter and the other eye uncovered.
Origin
1920s. From the name of Carl Pulfrich, German physicist, who described the illusion.