[Excerpt] Greater use of tests assessing competence in verbal, mathematical, technical arenas and in specific occupations for selecting workers will have important effects on the economy. First, the rewards for developing the competencies measured by the tests will rise and this will increase the supply of workers whh these competencies. Tests like the General Aptitude Test Battery predict job performance because they measure or are correlated with a large set of developed abilities which are causa}]y related to productivity and not because they are correlated with an inherited ability to learn. Legal barriers to increased use of tests assessing verbal, mathematical and technical competence have contributed to our society's tendency to under-rewards these achievements. The resulting weak incentives for hard study have contributed to the low levels of achievement of American high school students in science and mathematics.