The experiment behind it
In 1971 Roger Shepard and Jacqueline Metzler showed people pairs of 3D block figures and asked whether they were the same object. The time it took to answer rose in a straight line with the angle between the two, at about 60 degrees per second, as though people were turning a mental image at a steady speed until the two lined up.
That straight line was one of the first hard measurements of something happening inside the head rather than on the page, and it has been replicated many times since. This test uses the same logic with flat shapes, which are quicker to turn.
How your rotation speed is worked out
The test shows the shapes at five angles, from no turn at all to a half turn, in equal numbers and shuffled. It then fits a line through your correct answer times against the angle.
The slope of that line is the extra time each degree costs you, and turning it upside down gives degrees per second. Where the line starts, at zero degrees, is everything that is not rotation: seeing the shapes, deciding, pressing a button, and any lag your device adds. Leaving that out is why the number survives a change of screen, for the same reason the Stroop test scores a difference rather than a raw time.
The chart on your result shows the line itself: your average time at each angle. For most people the bars climb from left to right. That climb is the effect Shepard and Metzler found.
What the number is, and is not
There is no normative sample for this format, and the 60 degrees per second from the original study was measured on 3D figures, which are harder to turn than flat shapes. There is no honest way to turn your speed into a percentile, so this test does not give one. The labels on the result describe the speed rather than rank it against other people.
Where this site does quote a percentile, as on the digit span test, published normative data sits behind it.
Frequently asked questions
What is a good score on a mental rotation test?
Accuracy comes first. Guessing gets half the answers right, so a score only means something well above that, and most people who take their time get the large majority correct. Speed varies widely and there is no normative sample for this format. The best-known reference is the original 1971 study, where people turned 3D block figures at about 60 degrees per second. Flat shapes like these are simpler, so expect a higher number here.
What does a mental rotation test measure?
Spatial visualisation: the ability to hold an image in mind and transform it. Mental rotation is the most studied example, and it is one part of spatial reasoning rather than the whole of it.
Why mirror images?
Because a mirror image cannot be turned into the original by rotating it flat, however far you turn it. That means you cannot answer by spotting a single feature. You have to line the shapes up, and lining them up is the rotation being measured. Every shape in this test was checked to make sure its mirror image really is different.
Why is my score based on the slope and not my total time?
Total time mixes the rotation with everything else: seeing the shapes, deciding, pressing the button, and any lag your device adds. None of that changes with the angle, but rotation does. Measuring how much longer each extra degree takes isolates the rotation from the rest, which is also why the number holds up across devices.
Is mental rotation related to IQ?
Yes, as one part of it. Spatial reasoning is one of the broad abilities that major IQ batteries measure, and mental rotation tasks correlate with it. A strong rotation speed says your spatial visualisation is quick. It does not stand in for a full score, which also draws on verbal, numerical and memory abilities.
Can you improve at mental rotation?
Yes, and more than for most cognitive skills. A large 2013 meta-analysis of spatial training studies by Uttal and colleagues found that spatial skills respond to practice, that the gains last, and that they carry over to some untrained spatial tasks. Repeating this test will make you faster at it, partly for that reason and partly through familiarity with the shapes.