An ambiguous figure appearing as a staircase viewed either from above or below, a classic illustration of perspective reversal (see illustration). Also spelt Schroeder staircase. Often confused with the staircase illusion. [Named after the German bacteriologist and psychologist Heinrich G. F. Schröder (1810–85) who first published it in 1858]
Schröder staircase. The perspective alternates spontaneously between views of a staircase as seen from above and from below.