The tests conducted upon the male adult population of the United
States, during the Great War, revealed the astonishing fact that the
average mental “age” was approximately twelve years; that is to say,
the average adult possesses an intelligence of a boy at that age.
The body may have grown, but the mind has not! Of course, many were
above that level; but many fell below, and the above represented the
_average_. In many other countries, the average would certainly have
been far lower.
The majority, therefore, do not possess normal adult minds; there
has been an arrested development. A scale of mental development was
accordingly constructed, and individuals were placed somewhere in that
scale. The human mind may be anything, from a genius to an idiot.
In this scale, there were many “defectives.” Those individuals who
possessed a mentality of from eight to twelve years, were classed as
“morons”; those who ranged from three to seven years, “imbeciles”; and
those of two, and under, “idiots.”
The mental-age or intelligence-level of any person may be ascertained
by special tests, devised for the purpose. These tests were originated
by the psychologist Binet, but Terman and others have greatly extended
and amplified the original methods. Such tests have now been conducted
extensively, and the results show us that surprisingly low levels of
intelligence are the rule, and not the rare exception. The importance
of an extensive educational campaign is therefore manifest; and the
Editor of this series, Mr. Haldeman-Julius, is carrying on one of the
most important campaigns in the world today--by spreading general
culture and education. For, by this means alone, and by suitable
eugenic measures, can the human race be elevated and improved, with
each succeeding generation.