Bridget Riley (see Wikipedia)
Why the name MONKEY PUZZLE assigned to this blocK? Maybe something to do with "monkey business." The monkey is the creature most ingenious and mischievous and apt to steal a banana or two. And the design is likewise a kind of "Robbing Peter to pay Paul" type of sleight of hand, swapping dark for light, whilst itself off-kilter, and seeming somewhat foolhardy or silly perhaps in its diagonal position. The original calls for alternating the tiling with plain blocks. The variation here uses half blocks, so as to allow for a geometrically briefer separation between the adjoining circles.
This is the same pattern as LILIAN'S FAVORITE, first published in 1906, Clara Stone, Practical Needlework. See Jinny Beyer's QUILTER'S ALBUM OF PATCHWORK PATTERNS (p.310-3) in the delightful "Two by Two Base Grid Category with Curved Elements" section — also Barbara Brackman's ENCYCLOPEDIA (#3188), where MONKEY'S PUZZLE is assigned to the "Equal Diagonal Division" category. If the design is rotated as a four-patch block, it is called FORE AND AFT (Nancy Cabot, 1936).
The current rendering is an Op Art stylization (see more at ARRANGEMENT OF SMALL PIECES) with its geometric eye-popping intensity — notice the extended, reverse-S curves in the tiling pattern below, similar to Bridget Riley's magnificent black and white PAUSE illustrated left — though Riley, a great colorist also (see here) and a founder of the dazzling geometric Op-Art movement, an offshoot of Modernism.
Compare at this site with:
A THOUSAND PYRAMIDS
ROBBING PETER TO PAY PAUL