Peter Brookes, UK, 1979.
The above example is featured in a book titled “A Smile In The Mind” by Beryl McAlhone & David Stuart. Page: 49. ISBN: 0-7148-3812-8.
An optical illusion (also called a visual illusion) is characterized by visually perceived images that are deceptive or misleading. The information gathered by the eye is processed by the brain to give a percept that does not tally with a physical measurement of the stimulus source. There are three main types of illusion – literal optical illusions that create images that are different from the objects that make them, physiological illusions that are the effects on the eyes and brain of excessive stimulation of a specific type – brightness, tilt, color, movement, and cognitive illusions where the eye and brain make unconscious inferences. – Wikipedia.
Source of the above visual: Algo le pasa al gato