Task library
Perception Shepard & Metzler, 1971

Mental rotation task

Is the rotated letter normal or mirror-reversed? The further it is turned, the longer you take, as if you were turning it in your head.

Measures
Spatial transformation speed
Template length
about 4 minutes (32 trials)

A letter appears, rotated by some angle and sometimes mirror-reversed. You decide as quickly as you can whether it is normal or mirrored.

Response time grows steadily with the angle of rotation, as if people were rotating a mental image back to upright at a fixed speed. It was one of the first demonstrations that mental images can be studied with response times.

Try it yourself

A shortened run of the same template researchers use. Nothing is recorded and you do not need an account.

How the task works

  1. 1A fixation cross appears for 500 ms.
  2. 2A letter appears at one of eight angles. Press F if it is normal and J if it is mirror-reversed.
  3. 3You have 5 seconds per trial.

What people usually find

Response time increases roughly linearly from 0° up to 180° and falls again beyond it, since 270° is the same as 90° the other way. Errors also rise with angle. Mirrored letters are usually a little slower than normal ones.

How to score it

  • Rotation slope: fit a line to mean correct RT against angular distance from upright (0 to 180°). The slope, in ms per degree, is the rate of mental rotation; its inverse is degrees per second.
  • Use correct trials only, and fold angles over 180° onto their mirror (for example 270° → 90°).

Before you run it

  • Letters are a 2D version. The original study used 3D block figures and compared pairs of images; ask for that variant if you want to compare with the Shepard–Metzler literature.
  • The template crosses 8 angles with normal and mirrored versions, twice each (32 trials), drawing the letter at random from six. Slopes stabilise with 10 or more trials per angle.

Run it as a study

Use the template as it is

The demo above is the same code as the Mental Rotation template in the gallery. Add it to a project, change the settings in config.js, publish it and share the link. Reaction times and responses come back to your dashboard.

Create a free account to use it

Or build a variant: compare two rotations side by side

Paste this into the AI panel in the experiment editor. Read the code it writes before you collect anything.

Build a mental rotation task with pairs of polygons. On each trial show two random 8-sided polygons side by side: the right one is the left one rotated by 0, 60, 120 or 180 degrees, and on half of the trials it is also mirror-reversed. Press F for "same shape" and J for "different". Generate 8 polygons, cross them with the 4 angles and same/different for 64 trials, and show feedback during 8 practice trials. Record the angle, whether the pair was mirrored, and the response.

Common questions

What does mental rotation measure?

How quickly and accurately people can transform a visual image in their mind. It is a core part of spatial ability.

Why does it take longer for bigger angles?

The classic explanation is that people rotate a mental image through intermediate angles at a fairly constant rate, so a bigger turn takes proportionally longer.

Can I use 3D shapes instead of letters?

Yes. Ask the AI builder for Shepard–Metzler style figures, or upload your own images as stimuli and use them in the template.

References

  1. Shepard, R. N., & Metzler, J. (1971). Mental rotation of three-dimensional objects. Science, 171(3972), 701–703.
  2. Cooper, L. A., & Shepard, R. N. (1973). Chronometric studies of the rotation of mental images. In W. G. Chase (Ed.), Visual information processing (pp. 75–176). Academic Press.