The Latin verb illudere, meaning to deceive or fool, is an etymological ancestor of the English word illusion.
In addition to being one of the easiest ways to gauge a person's IQ and focus, optical illusion visuals are intentionally misleading.
Some research suggests that practicing solving optical illusion puzzles on a daily basis can aid with general problem solving abilities.
A grid of nines is shown to the viewer in the aforementioned image.
Number 6 is the only one that doesn't match up in the grid.
Readers have only four seconds to find the hidden six amid the nines.
Do you think you have what it takes to find it in the allotted time?