The Forer Machine

You will be asked for a birth date, time and place. That is the ritual, and it is theatre: the details stay in your browser and are never transmitted. No birth data reaches our server, our database, or the published dataset — there is no field in the request and no column in the table. Open your browser's network tab while you use this page and you will find nothing carrying it.

What is withheld until you have rated is only that the text is fixed and that a second version exists. Both are shown the moment you submit, on this same page.

People rate vague, universally applicable descriptions as strikingly accurate accounts of themselves — the Barnum effect, after Forer's 1949 classroom demonstration. Demonstrations of it are everywhere; controlled measurements are rarer, because a single generic text gives you a number with nothing to weigh it against.

So this register has two arms. Half of participants read a description built to fit nearly anyone: double-sided, mildly flattering, impossible to disprove. The other half read one of the same length and rhythm making concrete claims — about sleep, about animals, about numbers — that cannot be true of most people. If the first is rated substantially higher, the effect is real and measured rather than merely displayed.

Fixed in advance: Welch's two-sample t-test on mean rating, two-sided, α = .05, with Cohen's d and a Mann–Whitney U reported alongside because a 1–10 rating is ordinal. Reads at 1,000, 5,000 and 10,000 entries. Assignment is deterministic on your participant identifier, so reloading cannot move you between arms.