Shadow Match

About this test

Comparing two near-identical shapes is a visual matching task, and intuition handles it badly. A general impression — "that one looks the same" — works while the differences are coarse and becomes useless once they drop below a few percent. What works is picking one precise detail and checking only that.

The game generates a random shape each round, then builds the decoys by changing exactly one thing: the rotation, the horizontal stretch, or the distance of one vertex from the centre. The longer your streak, the smaller that change and the more decoys there are, from four up to eight. The clock does not move, though: sixty seconds, and every hesitation costs an answer.

The strategy that changes everything fits in a sentence: find the most recognisable vertex on the top shape — usually the one pulled inwards — and hunt only for that vertex in the shadows. Players who compare whole silhouettes plateau around twenty answers, however good their eyesight.

How it works

Each round draws a random target shape plus three to seven decoys, each made by altering a single parameter. The number of options climbs from four to eight as you get answers right, and the size of the warp drops from about forty percent to five. A wrong answer costs nothing but time. A run lasts sixty seconds and your score is the number of correct answers: six scores zero out of a hundred, forty scores one hundred.