20 spatial puzzles measuring how well you turn shapes in your mind. No words, no numbers.
Mental rotation is the ability to picture an object turning and judge how it would look from a new angle. Shepard and Metzler showed in 1971 that the time people need rises almost linearly with the angle they must rotate through, which is why it is treated as evidence of a real internal transformation rather than a guess. It is one of the clearest markers of spatial ability, a factor that sits apart from verbal and numerical reasoning.
Each incorrect option is the target figure reflected, not a different shape. That matters: if the foils were simply other shapes you could solve every item by counting squares, and the task would measure attention instead of rotation. A reflected figure can never be produced by turning the original in the plane, so telling them apart requires actually rotating it in your head. Every figure is checked to be asymmetric before use, because a symmetric shape is identical to its own mirror image and would have no single right answer.
Does practice help? Yes, more than for most cognitive tasks. Spatial skill responds well to training and the gains carry over to related spatial problems, though not to unrelated abilities.
Why 20 figures? Enough to cover both small and large rotations so the score reflects the full range, while keeping the test to about six minutes. Figures are built fresh each attempt, so there is no answer key to memorise.