About this site

Who runs this site

This site is run by headon. The details from the imprint:

Responsible: Onur Cirakoglu, founder of headon

This site was designed and developed by headon.pro – studio for web & interaction.

headon Owner: Onur Cirakoglu Am Vogelsberg 8 97922 Lauda-Königshofen Germany VAT ID: DE266866658

How the content is made

• It is based on the original studies (primary sources), not on reports about them.
• Figures stated as facts are kept in a central list together with their source and the exact passage. Automated checks flag any language version that gives a different figure.
• In September 2026, the factual statements on this site were checked against the original studies; errors found were corrected.
• Where research is inconsistent – for example on the boundary between aphantasia and weak imagery – we say so.

How the language versions are made

• The German version is the original. The pages in English, French, Spanish and Polish are translations of it.
• In September 2026, the French, Spanish and Polish versions were translated back into German by an AI (Claude) and compared with the German text; clear errors of meaning were corrected. They have not yet been proofread by native speakers.
• This back-translation covers the reworded test questions as well as the changed result texts and FAQ answers. The knowledge pages and the glossary have not been fully back-translated; there, automated tests so far only check that every version gives the same figures.
• The original VVIQ by David Marks is only available in its English wording – it is not translated.

What the tests are

The VST-16 follows the methodology of the VVIQ (Marks 1973) with its own everyday scenarios; the MST-21 is modelled on the PSI-Q (Andrade et al. 2014).

Developed in-house on the basis of the research literature. Modelled on established instruments, but not independently validated. Not a diagnostic procedure – the results are intended for self-assessment.

What happens to your data

• There are no accounts and no sign-in.
• Your answers are not transmitted to our servers. Before the test, you decide whether your result is only shown during this session or saved in your browser on this device.
• You can delete saved results yourself at any time.
• For visitor statistics we use Rybbit – self-hosted and without cookies.

No advertising

This site shows no ads and contains no paid links.

Found a mistake?

If you notice a wrong figure, an outdated source or a misleading sentence, write to us – ideally with a link to the page and, if possible, to the source.