Set A is a jigsaw. A large field of texture, lines, a grid, rings, a radial fan, has a square cut out, and the six pieces below are candidates for the hole. Most of the twelve are plain: the texture simply continues. A few step: the lines get closer, the count rises, the size grows, in one direction or two.
What you see: a piece missing from a pattern. What you do: carry the pattern across the gap.
The tactic
- Read the grain first. Which way do the lines run, how far apart, do they bend? The correct piece continues every line that meets the hole's edge.
- Check the edge, not the middle. Put your eye on the hole's border and ask what must arrive at each side. A piece that is right in the middle and wrong at one edge is wrong.
- If the field changes across itself, find the direction. Lines getting denser to the right, rings getting larger outward: the piece must sit at the right point of that progression, not merely look like its neighbours.
The wrong pieces
They break one thing. A line that stops at the border; the right texture rotated; the right pattern at the wrong density; a plausible piece from the other side of the field. The check that catches all four is the edge check.