The red and green shapes in this test's overlay correspond directly to the red and green glasses the client is meant to wear during the test.

The client positioned 3 meters away from the overlay, which is strongly suggested to be placed on a suitable white light screen. The client gets to wear the red and green glasses and is now asked to describe all the symbols on the overlay. He will only see all of them if BOTH eyes work together, otherwise one of the circled symbols will appear to be black.