IJ 8 THE MISMEASURE OF MANmajority of authors do not publish; one does not want to let them
be known." Both Binet and his student Simon had measured the
same heads of "idiots and imbeciles" at a hospital where Simon was
in intern. Binet noted that, for one crucial measurement, Simon's
values were consistently less than his. Binet therefore returned to
measure the subjects a second time. The first time, Binet admits,
"I took my measures mechanically, without any other preconcep-
tion than to remain faithful to my methods." But the second time
"I had a different preconception. ... I was bothered by the differ-
ence" between Simon and myself. "I wanted to reduce it to its true
value.... This is self-suggestion. Now, capital fact, the measures
taken during the second experiment, under the expectation of a
diminution, are indeed smaller than the measures taken [on the
same heads] during the first experiment." In fact, all but one head
had "shrunk" between the two experiments and the average dimi-
nution was 3 mm—a good deal more than the average difference
between skulls of bright and poor students in his previous work.
Binet spoke graphically of his discouragement:I was persuaded that I had attacked an intractable problem. The mea-
sures had required travelling, and tiring procedures of all sorts; and they
ended with the discouraging conclusion that there was often not a milli-
meter of difference between the cephalic measures of intelligent and less
intelligent students. The idea of measuring intelligence by measuring
heads seemed ridiculous. ... I was on the point of abandoning this work,
and I didn't want to publish a single line of it (1900, p. 403).At the end, Binet snatched a weak and dubious victory from
the jaws of defeat. He looked at his entire sample again, separated
out the five top and bottom pupils from eacb group, and elimi-
nated all those in the middle. The differences between extremes
were greater and more consistent— 3 to 4 mm on average. But even
this difference did not exceed the average potential bias due to
suggestibility. Craniometry, the jewel of nineteenth-century objec-
tivity, was not destined for continued celebration.Binet's scale and the birth of IQ
When Binet returned to the measurement of intelligence in
1904, he remembered his previous frustration and switched to
other techniques. He abandoned what he called the "medical"