A relative size illusion was discovered by Italian visual researcher Gianni A. Sarcone in 2013. This illusion called Sarcone’s Crosses contradicts Ebbinghaus illusion (aka Titchener Circles, 1898) and Obonai square illusion (1954). In fact, the central test shape (cross) surrounded by large squares appears larger instead of smaller.
Sarcone’s cross illusion consists of a cross (the test shape) surrounded by sets of squares of distinct size (the inducing shapes). As shown in the diagram opposite, the three blue crosses are exactly the same size; however, the one on the left (fig. 1) tends to appear larger. The illusion works even when the small squares completely occlude the blue cross (see fig. 3). In conclusion, there isn’t always a correlation between the size of the surrounding shapes and the relative size perception of the test shape.
Take this optical illusion test to your brain.
