Versuche mit der waagrechten strecke-punkt-figur

The straight line-dot-illusion with horizontally extending figure was ascertained experimentally and explored under several conditions. In the case of binocular perception two “external” and one “internal” factors were found influencing the intensity of the illusion. Observations with right eye and left eye respectively proved themselves to be unequal. The previous interpretations of optical illusions failed to provide a satisfactory explanation of the straight line-dot-illusion. A new explaining assumption was considered.