Top 10 il­lu­sions facts

Both are the same. This is the well known checker shadow illusion, first published in 1995 by Edward H. Adelson, Professor of Vision Science at MIT. The area A appears darker because of its light surrounding. At the same time, area B, surrounded with dark areas, appear lighter.

None. In this scintillating grid illusion, dark dots seem to appear and disappear randomly. Various theories have been proposed to explain it. It may be caused by the mechanism of lateral inhibition (the capacity of an excited neuron to reduce the activity of its neighbors).

Refraction of light in ice crystals. Halo is the name for a family of optical phenomena produced by light interacting with ice crystals suspended in the atmosphere. Halos can have many forms, ranging from colored or white rings to arcs and spots in the sky. Among the best known halo types are the circular halo (properly called the 22° halo), Other common optical phenomena involving water droplets rather than ice crystals include the glory and the rainbow.

Small droplets or ice crystals. The effect is similar to irisation. Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light. Larger ice crystals do not produce iridescence, but can cause halos, a different phenomenon.

Her mysterious smile. Mona Lisa is famous for an optical illusion aka 'the mysterious smile'. The illusion is caused due to peripheral vision as the focus of the viewer shifts from the eyes of the portrait to the lips of the portrait.

Australia. This is Australia map, with north at the bottom side.

Marylin Monroe. A Hybrid Image is an optical illusion developed at MIT in which an image can be interpreted in one of two different ways depending on viewing distance. In order to see Marylin clearly, you need to move away of the screen

Red one. This is known as Poggendorff illusion, first described in 1860. Many detailed studies of the illusion point to its principal cause: acute angles in the figure are seen by viewers as expanded.

None of them. Both shapes are the same, but the bottom one is placed more to the right. This is however difficult to notice. It is known as Jastrow Illusion.

Both are the same size. This is known Ebbinghaus illusion. Although commonly thought of as an illusion of size, recent work suggests that the critical factor in the illusion is not the size, but the distance of the surrounding circles. In a similar way, the Moon appears larger on clear sky when it's close to the horizon line.