The Mismeasure of Man by Stephen Jay Gould

THE HEREDITARIAN THEORY OF IQ (^243)
Others, for whatever reasons, could not fathom the instructions
and scored zero. With high levels of imposed anxiety, poor condi-
tions for seeing and hearing, and general inexperience with testing
for most recruits, it would be fatuous to interpret the zero scores
as evidence of innate stupidity below the intelligence of men who
made some points—though Yerkes wormed out of the difficulty
this way (see pp. 244—247). (My own students compiled lowest rates
of completion for the tests that yield the largest secondary modes
at zero in Yerkes's sample—tests 4 and 5. As the only exception to
this pattern, most of my students completed test 3, which produced
a strong zero mode in the army sample. But 3 is the visual analog
of "what is the next number in this series," a test that all my
5*6 Frequency distributions for four of the Beta tests. Note the promi-
nent mode at zero for tests 4, 5, and 7.
TEST A,
6 ETA
TEST 6,
BETA
TEST X BETA
TEST ST BETA