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Spatial reasoning

Shepard Mental Rotation

Two 3D-style shapes appear side by side. One may be rotated relative to the other. Decide — as fast as you can — whether they're identical or mirror images.

What makes this one different

We sample rotations across 0°, 60°, 120°, 180° and fit a slope to your reaction times. That slope is your personal rotation rate — how many extra milliseconds per degree of rotation. Most people don't know theirs.

Trial 0 / 24
Mean RT —
Accuracy —
Reference
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Your rotation rate

How much extra RT each degree of rotation costs you. Lower = better.

— ms/°
Your personal slope from this session

History

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What problem does it solve?

Mental rotation is the canonical spatial-reasoning task. Originally Roger Shepard's 1971 paper, it has been replicated hundreds of times: reaction time scales linearly with the angle of rotation, which is itself a striking finding — your brain doesn't "snap" shapes into alignment, it rotates them through space.

It correlates with math performance, engineering aptitude, and even some sports expertise (chess, dance). It's a clean, well-studied index of spatial cognition.

Who is this for

How to interpret your results

Slope (ms per degree) of 8–15 ms/° is typical for adults. Elite spatial reasoners get into the 4–6 ms/° range. Higher means each degree of rotation costs you more time.

Accuracy above 90% with reasonable RT is healthy. Below 75% suggests you're rushing or the shapes are too hard for current session.

Limitations

  • The classic Shepard task uses specific 7-cube 3D shapes; we approximate with custom 2D-projected L-shapes. The cognitive demand is similar but not identical.
  • We sample 4 angles (0°, 60°, 120°, 180°). Lab studies use more angles for higher-fidelity fits.
  • SVG rendering depends on browser and device. Performance should be consistent within a device.

FAQ

Does practice actually lower the slope?

Modestly. Most people see 10–20% improvement over weeks of regular practice, then plateau. The ceiling is real.

What does a very low slope mean?

You rotate shapes quickly — usually correlated with strong spatial skills. It does not mean you're "smarter overall"; spatial reasoning is one slice.