This is an example of the Gestalt law of continuation. The brain sees this image as a white triangle on top of another triangle on top of three black circles. http://www.ics.uci.edu/~kobsa/courses/ICS104/course-notes/gestalt-laws.htm
This design shows Gestalt through the play of the positive and negative space in the design. At first sight, you see two boys playing soccer, but on second look, you see the African continent made by their silhouettes.