Editorial & Sourcing Policy

This page explains how I make the content on Optical Wonderful: how I research the illusions, how I check who discovered what, where the images and illustrations come from, and what happens when something turns out to be wrong. Every page on the site is researched and written by me, Stuart Mathieson.

Research and fact-checking

I make each illusion page follow the same structure: what you're seeing, why it happens, and, where it's documented, who discovered or popularized it. For the "why it happens" part, I lean on the established consensus in vision science and cognitive psychology, not on novel or fringe theories. Where the science genuinely isn't settled (the moon illusion is a good example, with several competing explanations still under active discussion), I say so plainly instead of presenting one theory as the final word. Every illusion, science and artist page ends with a "Sources and further reading" list naming the original papers and books it draws on, so you can check any claim against the literature for yourself.

When it comes to history, I try to separate who is popularly credited with an illusion from who can be documented as its first publisher or formal describer. These aren't always the same person, and mixing them up is one of the more common mistakes in illusion writing elsewhere online. Where a date, name or detail can't be pinned down with confidence, my pages say so with appropriate hedging ("widely credited with", "generally dated to") instead of stating a precise fact that has been made up.

Image and illustration sourcing

Classic illusion diagrams are more tied up in copyright than people often assume. Many of the canonical images associated with famous illusions were created or published by specific researchers, artists or publishers who still hold the rights to them, and reusing them without a licence isn't automatically fair use just because the underlying illusion is old or well known. So instead of taking that risk, or using vague, uncredited "found online" images, I build the interactive demos on this site from scratch in HTML, CSS and JavaScript, matched as closely as I can to the actual visual structure of each illusion. Illusions that can't be rebuilt in code use illustrations made for this site; many of these are AI-generated, and their captions say so. The Image Sourcing Guide explains this approach and its trade-offs in more detail. Where an illusion depends on one specific photograph or piece of footage, the page links to the original where it's legitimately published, instead of reproducing a copyrighted image without a licence.

Corrections

If you spot a factual error, such as a wrong date, an incorrect attribution, an outdated scientific explanation or a broken link, please let me know through the Contact page, ideally with a source if you have one. I review every correction and, once I've verified it, apply it directly to the page. For anything beyond a minor fix, I refresh the page's "last updated" date so you can see that it has changed.

What this site is not

Optical Wonderful isn't a peer-reviewed publication, and it doesn't claim to be one. It's a reference and explainer site written for a general audience, built on publicly available scientific literature and well-documented history. If you'd like to go deeper than a general-audience explanation, the source list at the bottom of each illusion and Science of Perception page is the best place to start.