ABSTRACT
Modern intelligence theory begins in the year 1904, in which, simultaneously, Binet put forward the first practical intelligence test and Spearman published his theoretical breakthrough in the article, 'Intelligence Objectively Determined and Measured'. The difference between the practical and the theoretical streams has curiously persisted down to the present day. For most of a century, many psychologists have followed the Binet tradition of adding test to test according to a common sense idea of what intelligence is. Meanwhile, on a different level, Spearman's introduction of factor analysis has bloomed into a vast field of multivariate experimental attacks on theory. The technical proof of the lay is the fact that correlation tables could be arranged in a hierarchy falling from left to right and from above down. He noted that the highest correlations were for complex performance in mathematics, classical grammar and the like.
