This is one of a number of online tests for “Prosopagnosia” (face blindness). People who suffer from this condition find it hard to recognise people by their face alone.
How to take the test: Study the top left picture (green border) in the set. Select any other picture(s) you think are of this person, then press the next page button. Your recognition stats will be shown at the end.
If it all gets too infuriating, use the Cheat button to show all matching faces.