Forer Experiment (1949): What 39 Students Actually Rated

In a 1949 paper, psychologist Bertram Forer reported that he gave 39 students a personality sketch he said was built from their test answers. It was not. Every student got the same 13 sentences, taken largely from a newsstand astrology book. The class rated how well the sketch revealed their personality at 4.26 out of 5, and 34 of the 39 gave it a 4 or a 5.

That is the version you will find everywhere. Forer’s own tables tell a better story. The sketch did not land evenly: 38 of 39 students marked the self-criticism line true, and only 12 marked the line about unrealistic aspirations true. This guide goes back to the paper, recounts the numbers, and shows which sentences did the work.

Forer Experiment: Key Facts

Researcher: Bertram R. Forer, Veterans Administration Mental Hygiene Clinic, Los Angeles
Paper: “The Fallacy of Personal Validation: A Classroom Demonstration of Gullibility,” Journal of Abnormal and Social Psychology, volume 44, pages 118 to 123 (1949)
Sample: 39 students in one class
Sketch: 13 statements, identical for every student, taken largely from a newsstand astrology book
Result: mean rating 4.26 out of 5 (our recount of Table 1), with 34 of 39 students rating it 4 or 5
Conclusion: a feeling of “that sounds like me” does not show that a test works

What Did the Forer Experiment Show?

It showed that people accept a generic description as accurate when it feels aimed at them. Forer named the mistake the fallacy of personal validation: treating “that sounds like me” as proof that a test or a reading measures anything. The students approved of the test, and the test had never touched the sketch.

The Mechanics: How Forer Ran It

Forer ran the exercise in a classroom, in five steps.

The test. Students filled in the Diagnostic Interest Blank, a form listing hobbies, reading, personal traits, job duties and the secret hopes of an ideal person.
The sketch. A week later, each student received a typed personality sketch, presented as a personal result. All 39 copies matched.
The ratings. Students rated the test and the sketch from 0 (poor) to 5 (perfect). For the sketch, the question was how well it revealed their basic personality characteristics. They also marked each of the 13 statements true, false or unsure.
The reveal. Forer asked who thought the test had done a good job, and virtually all hands went up. He then read the sketch aloud item by item. By his account, hands rose for each line and the class laughed.
The follow-up. Three weeks later, 32 of the 39 students tried to recall their ratings.

Watch for: the usual retelling says students rated the sketch for “accuracy.” Forer’s question asked how well it revealed their personality. That is close, but it is not the same wording.

What Were the Actual Ratings?

Forer’s Table 1 counts the sketch ratings. We added them up ourselves.

Rating	Students
5	16
4	18
3	4
2	1
0 or 1	0
Total	39 students, 166 points, mean 4.26

The 4.26 follows from that table: 166 points over 39 students. We did not find the figure printed in the copy we read, so we rebuilt it. Thirty-four of 39 students, or 87 percent, rated the sketch a 4 or 5. Five rated it lower, and only one of those gave it a 2. The students also rated the test itself high: only one student gave the Diagnostic Interest Blank less than a 4.

Which Sentences Worked, and Which Did Not?

Table 3 of the paper records how many students marked each statement true. We list all 13 in order, with our own short labels. We calculated the percentages.

Statement (our label)	Marked true	Share
Self-critical	38 of 39	97%
Serious doubts about decisions	38 of 39	97%
Wants change and variety	37 of 39	95%
Outwardly controlled, inwardly worried	35 of 39	90%
Unwise to be too frank	35 of 39	90%
Independent thinker	34 of 39	87%
Alternates between outgoing and reserved	34 of 39	87%
Compensates for weaknesses	31 of 39	79%
Needs others’ approval	28 of 39	72%
Security is a major goal	28 of 39	72%
Unused capacity	23 of 39	59%
Sexual adjustment problems	18 of 39	46%
Unrealistic aspirations	12 of 39	31%

On average, each student marked 10.2 of the 13 statements true. The pattern is the interesting part. The two top lines are doubts nearly everyone admits to. The two weakest lines name something more pointed, sexual adjustment and unrealistic aspirations, and students pushed back on them. That is our reading, not Forer’s.

What Happened Three Weeks Later?

Of the 32 students who recalled their ratings, eight lowered their rating of the sketch, and none raised it. Seven of the eight dropped from a 5 to a 4. Forer read this as a sign of bruised pride after the reveal, not simple forgetting.

Where Sources Disagree

Year: the paper carries a 1949 date in standard citations. Many retellings place the class in 1948. The copy we read prints no date on its first page, so we cite the journal reference.
The mean: most sources say 4.26. One analysis calls a circulating figure of 4.30 a transcription drift. Our recount of Table 1 gives 4.26.
The book: Forer says the statements came largely from a newsstand astrology book. He does not name it, so we do not either.
The tables: Table 2 adds to 399 true marks, which is the 10.2 per student. Table 3 adds to 391. The paper does not reconcile the two. We used each table only for its own figure, and we read a scanned copy, so a scan error on our side is possible.

The Five-Point Binary Grid: What the Study Shows and Does Not Show

This operational grid is our own diagnostic, not part of Forer’s paper.

Spec	What it shows	What it does not show
Sample	One class of 39 students accepted a generic sketch	How adults accept readings in daily life
Mechanism	Approval is weak evidence that a test works	That approval is always wrong
Spread	Acceptance ran from 12 to 38 of 39 across statements	That every sentence fools every reader
Source	Horoscope-style wording felt personal	Whether any astrologer can read a chart well
Containment	Check a reading with a test that can fail	That astrology or tarot works or fails

That last row matters. Forer tested the proof method, not astrology. For a test that could have failed, see our write-up of the Carlson double-blind test.

Recorded Symptoms

These are illustrative composites, not real case files.

Symptom 1. A reader opens a sun-sign page and ticks nine of ten lines as true. She calls it uncanny. She never asks whether the page for another sign would also score nine.

Symptom 2. A team lead reads a profile from a workplace quiz and finds it flattering and exact. He shows it to three colleagues, and each says theirs fits as well. The quiz never has to be right, because the feeling of fit arrives first.

Insulation Protocols: Test a Reading the Forer Way

Mark every line. Write true, false or unsure beside each statement, as Forer’s students did, before you judge the whole.
Swap the label. Read the text written for a different sign or number, with the heading hidden. If it still fits, the text is generic.
Hunt for lines that can fail. Forer’s two weakest sentences were the pointed ones. A line you can check against your life beats a line about your doubts.
Ask someone who knows you. Show a friend two readings and ask which one is yours.
Separate the feeling from the method. A reading that feels right tells you about the wording. It does not tell you the method works.

Plain note: no study shows that a sign, a number or a card predicts your outcomes. If a reading worries you, put it down and talk to a person.

FAQ

What was the Forer experiment?

It was a 1949 classroom demonstration by psychologist Bertram Forer. He gave 39 students one identical personality sketch and told each it was personal. They rated it 4.26 out of 5 on average.

How many students were in the Forer experiment?

There were 39 students in one class. Thirty-two of them recalled their ratings three weeks later.

What did Forer use to write the sketch?

He assembled 13 statements, largely from a newsstand astrology book. None came from the students’ test answers.

What is the difference between the Forer effect and the Barnum effect?

They name the same effect. Psychologist Paul Meehl coined “Barnum effect” in a 1956 paper, and many researchers prefer “Forer effect” to credit the original demonstration. Our Barnum effect explainer covers how it works in a reading.

Does the Forer experiment prove astrology is false?

No. It shows that feeling described is weak evidence that a reading is accurate. Testing astrology needs a design that can fail, such as a blind matching test.

Aftermath

The tradition says a sun-sign reading describes you. Forer’s classroom says the feeling that someone describes you comes cheaply. If you want a reading built from a birth time and place instead of a label, start with our natal chart guide, and keep your pen handy for the true, false and unsure marks.

External Data Check

Popular summaries often call the study proof that people believe anything. Forer’s own title uses the word gullibility, but later work moved toward other explanations. Reviews such as Snyder, Shenkel and Lowery (1977) point to features of the description and the source, such as how personal it feels and how expert the speaker seems. We read that review only through secondary summaries, so treat that point as a pointer, not a finding.

Sources

Forer (1949), “The Fallacy of Personal Validation”: a scanned copy hosted by Ragged University. Source for the setup, Tables 1 to 3 and the three-week follow-up.
Meehl (1956), “Wanted: A Good Cookbook,” American Psychologist, 11(6), 263 to 272: where “Barnum effect” comes from, as cited in reference lists.
Snyder, Shenkel and Lowery (1977), Journal of Consulting and Clinical Psychology, 45(1): read through secondary summaries only.

We could not verify: the book Forer used, the exact date of the class, the split of ratings for the test itself (the scan blurs the figures), the reason the paper’s tables differ by eight marks, and the contents of the 1977 review. The recount of the 4.26 mean and every percentage in this article are our own arithmetic, checked in code.

Last reviewed: 9 November 2026.