Thurstone Primary Mental Abilities (1938)

THE STUDY BEHIND THE MONOGRAPH

A test-by-test correlation table, analysed by a method its author had just invented

57testsCovering words, numbers, space, memory, perception and reasoning, in a battery that took several sessions to give.

240volunteersTested in the spring of 1934; most accounts describe them as University of Chicago students.

3fundersThe University of Chicago's Social Science Research Committee, the American Council on Education and the Carnegie Corporation of New York.

No. 1Psychometric MonographsThe opening number of the Psychometric Society's monograph series, applying the method of The Vectors of Mind (1935).

Sources disagree on the battery size: 57 tests in most accounts, 56 in some. The volunteers were University of Chicago students.

ROTATION TO SIMPLE STRUCTURE · SIMULATED

Same data, different axes: find the angle where each test belongs to one factor

Thurstone's centroid method first puts an axis through the middle of all the tests, so everything loads on it, a lot like Spearman's g. He then rotated the axes until each test loaded strongly on as few factors as possible. He named a factor only from loadings of .40 or more and treated anything between −.20 and +.20 as negligible. Turn the axes and count the tests that meet both rules.

— FACTOR I— FACTOR II

Rotation from centroid axes0°

TESTIIISIMPLE?

Verbal A0.57-0.45—

Verbal B0.57-0.35—

Verbal C0.64-0.47—

Verbal D0.46-0.39—

Spatial A0.570.42—

Spatial B0.550.35—

Spatial C0.570.50—

Spatial D0.510.34—

Near the centroid axes every test loads on Factor I, a g-like picture.0 / 8

Eight invented tests in two clusters (verbal-like, spatial-like), two factors only. The 1938 analysis rotated many more factors at once.

THE NAMED FACTORS

Seven abilities, each a cluster of tests that moved together

Verbal comprehensionUnderstanding words and passages.

Word fluencyProducing words quickly to a rule.

NumberFast, accurate simple arithmetic.

SpaceImagining shapes as they move or turn.

Associative memoryRemembering paired material.

Perceptual speedSpotting details and differences quickly.

ReasoningFinding rules (induction) and applying them.

Factor names as listed in reference summaries; descriptions are ours.

FACTOR W · 60 SECONDS

How many words can you produce, not just recognise?

Word fluency was one of the surprises: producing words fast was a separate factor from understanding them (V). Write as many words as you can that start with the letter shown.

A task in the spirit of fluency tests, not Thurstone's own; there are no norms here.

READY0:60

[object Object]

THURSTONE AGAINST SPEARMAN, THEN BESIDE HIM

Several factors, then a factor above the factors

1904Spearman's gOne general factor plus test-specific parts explains why all mental tests correlate.

1935The Vectors of MindThurstone's multiple-factor method: ask how many common factors a correlation table needs.

1938Primary Mental AbilitiesSeveral distinct factors explain test performance better than one common factor. Seven are named.

1941Factorial Studies of IntelligenceL. L. and Thelma Gwinn Thurstone, Psychometric Monographs No. 2: the primaries in schoolchildren.

1948A second-order factorNoting that the primaries correlate positively, Thurstone suggests factor-analysing those correlations, which yields something like g. Later hierarchical models, ending in Cattell–Horn–Carroll, put g and the primaries at different levels.

LOUIS LEON THURSTONE · d. 1955

Attitude scales, a journal and a factor method

1927A Law of Comparative JudgmentThe scaling method still named after him.

1928Attitudes Can Be MeasuredApplying scaling to opinions.

1935The Vectors of MindMultiple-factor analysis, developed from his 1933 APA presidential address.

1936PsychometrikaThe Psychometric Society's journal begins; Thurstone designs its cover.

1938Primary Mental AbilitiesPsychometric Monographs No. 1. Named Charles F. Grey Distinguished Service Professor and elected to the National Academy of Sciences.

1938Experimental school batteryA trial battery of primary-ability tests for schools is made available.

1947Multiple-Factor AnalysisRewrites and extends The Vectors of Mind; becomes the standard text.

1952–55North CarolinaRetires from Chicago and re-founds his Psychometric Laboratory at the University of North Carolina, where both Thurstones hold posts. Dies 29 September 1955.

REFERENCES

Sources cited on this page

[1]Thurstone, L. L. (1938). Primary Mental Abilities. Psychometric Monographs, No. 1. University of Chicago Press. Review notice, Mathematical Gazette 22 (1938).doi (review)Used for: Hero details: ix + 121 pp., 9s., publishers.

[2]Springer chapter abstract: Primary Mental Abilities, Psychometric Monographs No. 1.link.springer.comUsed for: First number of the series, Vectors of Mind method, three funders.

[3]International Encyclopedia of the Social Sciences: Thurstone, L. L. (via Encyclopedia.com).encyclopedia.comUsed for: 57 tests / 240 subjects, seven factors, 1948 second-order suggestion, school battery, career.

[4]Pioneers of Human Behaviour: Louis Leon Thurstone.pioneersofhumanbehaviour.comUsed for: Spring 1934 testing, Psychometrika cover, NAS, UNC, death date, 1941 monograph.

[5]Revised orthogonal rotational solution for Thurstone's original PMA battery. Psychometrika.link.springer.comUsed for: Naming rule (≥ .40) and negligible band (±.20); centroid axes and rotation.

[6]Cogn-IQ. Thurstone's 7 Primary Mental Abilities.cogn-iq.orgUsed for: Factor names; 56-test figure (conflict); CHC lineage.

[7]Wikipedia. Louis Leon Thurstone.en.wikipedia.orgUsed for: Works list and dates.

EDITORIAL RECORD

What changed in this revision

The monograph was not read in full; details come from its review notice, publisher abstract and reference entries. The commercial school battery has its own page (SRA Primary Mental Abilities, 1941).

REMOVED“First empirically derived multi-factor battery” as a headline claim, and Spearman's g described as “dominant in the UK.” Both were unsourced framings.

CORRECTEDThe 1938 work was a research monograph on a 57-test battery, not a published school test. The schools battery is a separate, later product.

ADDEDMonograph hero, the study in four numbers, a rotation-to-simple-structure simulator using Thurstone's .40 and ±.20 rules, the seven factors, the 1904–1948 debate strip, works and career, and 7 references.

FLAGGEDBattery size: 57 tests in most sources, 56 in one.

KEPTThe word-fluency sprint, now timed more gently and labelled as an illustration.

KEEP EXPLORING

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Part of the Historical IQ Tests Archive. Editorial content under CC BY-SA 4.0.

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