Modern factor analysis is the outgrowth of Spearman's original "2-factor" model of intelligence, according to which a mental test score is regarded as the sum of a general factor and a specific factor. As early as 1914, Godfrey Thomson realized that the data did not require this interpretation and he demonstrated this by proposing what became…

On the occasion of Psychometrika's fiftieth anniversary, the past twenty-five years' developments in mental test theory are reviewed. Psychometrika articles treating topics in test theory are listed in a bibliography. (Author/LMO)

Three developments over the past 15 years--our understanding of cognition, new techniques in technical psychometrics, and the computer explosion--form the basis for a proposal for new intelligence tests. These developments are reviewed, and both leaps and steps in intellectual assessment are proposed. (Author/RD)