History of Intelligence Theories

William Stern (1871–1938): The Individual Behind the Intelligence Quotient

Lamiell (1996) notes that if mentioned at all, Stern is known as “the IQ guy,” which in one sense is true enough. He was indeed the one who invented the formula for the intelligence quotient:

IQ=100\dfrac{\text{Mental Age}}{\text{Chronological Age}}

What is not typically mentioned is that he was a little embarrassed by his IQ idea and would have been happy if his name were not associated with it (Lamiell, 2003, p. 1). He wrote movingly about how IQ tests should not be used to degrade individuals (Stern, 1933, as cited in Lamiell, 2003):

Under all conditions, human beings are and remain the centers of their own psychological life and their own worth. In other words, they remain persons, even when they are studied and treated from an external perspective with respect to others’ goals….Working “on” a human being must always entail working “for” a human being….The psychotechnician has every good reason to take these considerations seriously. Because if there are places today where the term “psychotechnician” is uttered with something of a disdainful tone, that is due to the implicit or explicit belief that psychotechnicians not only intercede but interfere in the lives and rights of the individuals they deal with. The feeling is that psychotechnicians degrade persons by using them as a means to others’ ends. (pp. 54–55)

Stern wrote extensively about a wide variety of issues about intelligence, personality, individuality, and many other topics. It irked him that the IQ formula was the idea that caught on. Fortunately, scholars are beginning to remember Stern as more than just “The IQ guy.”

Stern’s Humanism & the Limits of Science

Stern used intelligence tests and other scientific approaches to understand people but also wanted to be clear about the limits of such approaches. His work did not constitute a romantic rejection of science but rather a clear-headed delineation of its proper boundaries. In arguably the first book on the psychology of individual differences, Stern (1900, as cited in Lamiell, 2003) provides this thought, which, provided suitably tasteful graphic design, should probably be made into framed posters that psychologists who cherish individuality can hang in their offices:

[E]very individual is a singularity, a one-time existing being, nowhere else and never before present. To be sure, certain law-like regularities apply to him, certain types are embodied in him, but the individual is not exhausted by these laws and types; there remains ever something more, through which the individual is distinct from others who conform to the same laws and types. And this last kernel of being, which reveals the individual to be thus and so, distinct from all others, is not expressible in the language of scientific concepts, it is unclassifiable, incommensurable. In this sense, the individual is a limiting concept, toward which theoretical investigation strives but can never reach; it is, one could say, the asymptote of science. (pp. 15-16)

If a whole poster seems a bit much, “The Individual—The Asymptote Of Science” would fit nicely on a bumper sticker.

Reading Recommendations

Selected publications Comments
The psychological methods of testing intelligence (Stern, 1914) Besides showing Stern to be extremely sensible and practical, this book is eye-opening in showing the extremely wide variety of very basic questions that had to be answered before IQ tests could be taken seriously.
William Stern (Stern, 1930) For those wishing to acquire some intellectual humility, Stern’s autobiography might do the trick. Stern’s prose is at times dense with ideas that at first seem like gibberish but upon close inspection are seen to be quite profound.


Lamiell, J. T. (1996). William Stern: More than “the IQ guy.” In G. A. Kimble, C. Alan Boneau, & M. Wertheimer (Eds.), Portraits of pioneers in psychology, Vol. II, pp. 73–85. Hillsdale, NJ: Erlbaum.

Lamiell, J. T. (2003). Beyond individual and group differences: Human individuality, scientific psychology, and William Stern’s critical personalism. Thousand Oaks, CA: Sage.

Stern, W. (1900). Über Psychologie der individuellen Differenzen (Ideen zu einer “Differentiellen Psychologie”) [On the psychology of individual differences (Toward a “differential psychology”)]. Leipzig: Barth.

Stern, W. (1914). The psychological methods of testing intelligence (G. M. Whipple, Trans.). Baltimore: Warwick & York. (Original work published 1912)

Stern. W. (1930). William Stern. In C. Murchinson (Ed.), A history of psychology in autobiography, (Vol. 1, pp. 335-388). New York: Russell & Russell,

Stern, W. (1933). Der personale Faktor in Psychotechnik und praktischer Psychologie [The personal factor in psychotechnics in practical psychology]. Zeitschrift für angewandte Psychologie, 44, 52–63.


8 thoughts on “William Stern (1871–1938): The Individual Behind the Intelligence Quotient

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