The MLAT was first published in 1959 by The Psychological Corporation and was still sometimes used as of 2004. In his paper "Fundamental considerations in testing for English language proficiency of foreign students", published in 1961, Carroll challenged the language testing field's reliance on discrete-point testing. This is an analytical approach to language testing in which each test question is meant to measure one distinct content point. Carroll supported using an integrative testing design, in which each question requires the test-taker to use more than one skill or piece of knowledge at a time and may be a more natural representation of the test-taker's knowledge of the language. Carroll's paper influenced the design of the Test of English as a Foreign Language, or TOEFL, which combined both discrete-point and integrative methods for the assessment. In 1962, Carroll presented his Model of School Learning. In the model, Carroll defined a hypothetical framework used to predict achievement in schools. The framework was made up of two kinds of variables: individual differences and instructional variables. Individual differences related to general intelligence, aptitudes and motivation while instructional variables related to instructional quality and duration. Carroll's 800-page work, "", was published in 1993. In the book, Carroll proposed his psychological theory about three different levels of cognition, the Three Stratum Theory. In 1994, he was one of 52 signatories on "Mainstream Science on Intelligence", a public statement written by Linda Gottfredson and published in the "Wall Street Journal" as a response to what the authors viewed as inaccurate and misleading reports made by the media regarding academic consensus on the results of intelligence research in the wake of the appearance of "The Bell Curve" earlier the same year. Selected from over 400 books and articles.