Impossible Triangle
This triangle cannot be built as a real object, only 2D art.


Explanation:
Its roots go back to 1934 when Oscar Reutersvärd made the first recognizable impossible triangle out of a strange two-dimensional representation of cubes; this artwork appeared on a Swedish postage stamp issued in 1982.

Impossible Triangle
This triangle cannot be built as a real object, only 2D art.


Explanation:
In 1954, Roger Penrose, after attending a lecture by the artist M. C. Escher, rediscovered the impossible triangle and drew it in its most familiar form, which he published in a 1958 article in the British Journal of Psychology, coauthored with his father Lionel.1 Penrose was also unfamiliar with the work of Reutersvärd, Piranesi, and others who had created impossible figures previously. Penrose's impossible triangle, unlike Reutersvärd's earlier version, was drawn in perspective, which added an additional size paradox to the object. In 1961, Escher, inspired by Penrose's version of the impossible triangle (he was sent a copy of the article by the Penroses), incorporated it into his famous lithograph "Waterfall."

Are the horizontal lines parallel or do they slope?


Explanation:
Geometric illusions are examples of how our mind attempts to find orderly representations out of sometimes ambiguous and disorderly 2d images. The images transmitted from our retina to our brain are imperfect representation of reality (for example 2d images cannot accurately represent 3d space). Our visual system is capable of performing complex processing of information received from the eyes in order to extract meaningful perceptions. Sometimes, however, this process can lead to faulty perceptions.

These look like random shapes . . . until you move the mouse over them.

Explanation:
The effect presumably is related to the fact that the borders of letters vs. background are indistinguishable from the borders of letters vs. ink blot.

Are these circles actually moving?
Get an explanation by clicking here