Yerkes-Bridges Point Scale (1915)

Two ways to read the same answers

Binet age scaleYerkes-Bridges point scale

ITEMSDifferent tasks at each age level.A single series of measurements, given to everyone.¹

CREDITPass or fail at each age.Each measurement is graded on a scale of credit.¹

RESULTA mental age.Points out of 100, read against norms for the person's group.¹

COMPARISONAgainst the typical child of that age.Score ÷ the norm for the person's group = the coefficient of mental ability.¹

EXPLORE · GRADED CREDIT AND THE COEFFICIENT

Give credit, then compare with a group

Set the partial credit earned on each measurement. The total is out of 100. Then pick the norm for the person's group: the coefficient is the score divided by that norm.¹

Group norm (average score)60

Memory for digits

8/12

Defining words

10/14

Comparing two objects

9/12

Copying a design

5/10

Arranging a sentence

7/14

Interpreting a picture

6/12

Answering a comprehension question

9/14

Finding a rhyme

4/12

58points out of 100

0.97coefficient of mental ability (÷ 60)

Below the group normclose to the group's average

Eight illustrative measurements with invented credit steps that add up to 100. They're not the 1915 scale's actual list or weights. The scoring logic follows the 1915 paper.

From a Boston ward to the Army

Early 1914The point scale is ready for use. Examiners test pupils in the public schools of Cambridge, Massachusetts, as well as patients in the Psychopathic Hospital.⁴

Dec 1914Yerkes presents the method to the National Academy of Sciences, stressing that its value depends on reliable norms.¹

1915The 218-page monograph with James Bridges, then an intern, and Rose Hardwick, an assistant in psychology, is published.²

1915The authors already call the scale tentative and provisional, and see that it could be replaced by a better one.⁴

c. 1916+A combined record sheet pairs the Yerkes-Bridges point scale with the Stanford revision of the Binet-Simon for testing adult women.³

References

[1]Yerkes, R. M. (1915). A point scale for measuring mental ability. Proceedings of the National Academy of Sciences, 1(2), 114–117. Presented 4 December 1914 (PDF).pnas.org

[2]Yerkes, R. M., Bridges, J. W., & Hardwick, R. S. (1915). A point scale for measuring mental ability. Baltimore: Warwick & York. Wellcome Collection.wellcomecollection.org

[3]Psychological test record sheet: combination of Yerkes-Bridges Point Scale and Stanford Revision of Binet-Simon Scale for use with adult women. National Museum of American History, Smithsonian.americanhistory.si.edu

[4]A Point Scale for Measuring Mental Ability (Classic Reprint), publisher's excerpt from the 1915 monograph. The Great British Bookshop.thegreatbritishbookshop.co.uk

[5]A point scale for measuring mental ability (catalogue record and scan). Library of Congress.loc.gov

HOW TO CITE THIS PAGE

What's Your IQ. (2026). Yerkes-Bridges Point Scale (1915). In Historical IQ Tests Archive. Retrieved October 1, 2026, from /en/historical-iq-tests/yerkes-bridges-point-scale-1915

EDITORIAL RECORD

First published2026

Last reviewed1 October 2026

Sources5: the 1915 PNAS paper, library and museum records, and a reprint excerpt

Open questionsThe scale's exact list of measurements and credit weights, which are in the 218-page monograph

Canonical URLwhats-your-iq.com/en/historical-iq-tests/yerkes-bridges-point-scale-1915

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The age scale it reworked1905

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Yerkes opened his 1915 paper by describing Binet's method of estimating capacity in terms of age. The point scale kept Binet-style tasks but scored them on a single graded series.

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Where Yerkes went next1918

Army Alpha

Yerkes went on to lead the psychologists who built the WWI Army tests. There, a single printed series scored in points was given to recruits in groups.

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Goddard's translation spread the age-scale Binet across the United States. The Boston group offered the point scale as an alternative for adults as well as children.

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A year later Terman's Stanford-Binet kept age levels and reported an IQ. It, not the point scale, became the standard individual test.

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Part of the Historical IQ Tests Archive. Editorial content under CC BY-SA 4.0. The 1915 monograph and PNAS paper are in the public domain; read the monograph at the Library of Congress.

BibTeX RIS

Points, not ages.

Two ways to read the same answers

Give credit, then compare with a group

From a Boston ward to the Army

References

Related historical tests

A score against your group. Still the idea today.