Mental rotation, not a mirror

What a round looks like

The reference looks like an L made of blocks. One option is that L turned a quarter turn. Another is its left and right mirror. The mirror is wrong, because you would have to flip it over, not just turn it, to make it match.

Where the idea comes from

Mental Rotation is inspired by this research:

• Shepard, R. N., & Metzler, J. 1971. Mental rotation of three-dimensional objects. Science, 171, 701 to 703.Showed that the time people need to compare two rotated shapes grows with the angle between them.

Our puzzles use that general format with original figures drawn on a flat grid. They are not a licensed psychometric test.

For what large studies found about brain training, including the limits, see what the science actually says.

How it plays in Brain Puzzle

You get a short timed set of comparisons. Higher levels use more complex shapes and less time. A session score in the app is for play, not a measure of intelligence.

Difficulty that follows you

Each puzzle type keeps its own level on a scale from 1 to 10, so a strong run in one game does not make another one harder. After every round, the app looks at your recent results for that type.

A steady run of accurate rounds played at a good pace moves the level up one step. A run of rounds with half or fewer answers correct moves it down one step. Quick guesses that turn out wrong never count toward a step up.

The aim is to keep each puzzle challenging but playable. The level describes the game you get, not your intelligence, memory, or health.