levels of intelligence
in theories proposing that intelligence can be envisaged as a series of levels, general ability comes at the top of the hierarchy and successively narrower abilities come at lower levels. In one variant, the top level comprises general ability, the second level major group factors, the third level minor group factors, and the fourth level specific factors. Major group factors are those that are measured by many (but not all) intelligence tests, whereas minor group factors are ones that are measured by a smaller number of tests. Specific factors are measured only by single tests.