In 1948, psychologist Bertram Forer gave his students a personality test and told each of them the resulting written assessment had been prepared individually, based on their answers. In fact every student received the identical paragraph, assembled by Forer from generic, non-specific statements lifted from a newsstand astrology column and deliberately mixing favorable traits with ones that read as candidly self-critical but were, on close reading, vague enough to apply to almost anyone. Asked to rate how accurately the assessment described them personally, students gave it an average score of roughly 4.26 out of 5, a striking result given that every person in the room had just read the exact same sentences.
Forer's explanation was not that the statements were secretly true of everyone in some deep sense, but that they were constructed to be unfalsifiable and flattering in ways that let each reader supply their own confirming details, a technique long used, consciously or not, by fortune tellers, astrologers and similar practitioners well before Forer gave the underlying mechanism a name and a controlled classroom demonstration. Subsequent replications across the following decades, using different generic paragraphs and different subject pools, from college students to job applicants, have reproduced essentially the same high self-rated accuracy, reinforcing that the effect depends on the statements' structure rather than on anything particular about Forer's original 1948 classroom or the specific students in it.