Kinetic art expressions based on optical and luminous phenomenon as well as painting illusionism. The expression "kinetic art" in this modern form first appeared at the Museum für Gestaltung of Zürich in 1960, and found its major developments in the 1960s. In most European countries, it generally included the form of optical art that mainly makes use of optical illusions, such as op art, represented by Bridget Riley, as well as art based on movement represented by Yacov Agam, Carlos Cruz-Diez, Jesús Rafael Soto, Gregorio Vardanega, or Nicolas Schöffer. From 1961 to 1968, GRAV ("Groupe de Recherche d’Art Visuel") founded by François
Jastrow illusion findings have recently been contradicted. Recent research, which included the Jastrow illusion, placed these findings in doubt. The Jastrow illusion has been used to see whether young children are deceived by geometric optical illusions. Researchers used ring segments that were not equal in size so they could simulate both illusionary and real size differences. The showed the two segments in three configurations. The smaller shaded smaller segment was placed on top to emphasise the difference in size. In the other positions, the smaller piece was placed below or above the larger piece to create the illusion it is bigger. The