His research not only led him to develop the concept of the g factor of general intelligence, but also the s factor of specific intellectual abilities. Stratum III represents a single general level of intelligence, similar to Spearmans g (Sternberg & Kaufman). Some agree on the existence of general intelligence, albeit the nature of g is hotly debated, and some disagree completely with the notion of g. The main theories to consider after Spearmans are multifactor theories and hierarchical theories. He disagreed with Thurstones model and pointed out the intercorrelation between the factors said to represent Thurstones primary abilities. Unlike Spearmans theory of g, Cattells model suggested that g was made up of two components; crystallised intelligence (Gc) and fluid intelligence (Gf). Castejon, Perez and Gilar (2010) point out that there is a significant lack of empirical evidence to support multiple intelligence theories.There is much continued debate over the existence and nature of ¿½g¿½. The next level contains minor group factors; verbal, numerical and educational abilities which stem from v:ed, and practical, mechanical, spatial and physical abilities which stem from k:m. These minor groups then branch into specific factors. Since Spearman first suggested a general factor of intelligence (g) in 1904, many theorists have developed their own ideas about the nature of intelligence. Intelligence has always been an important component in the study of psychology. ).Gardner ‘s multiple intelligences theory challenges Spearman¿½s ¿½g¿½ by suggested there are 9 completely distinct intelligences (Maltby, et al., 2010). Both he and his opponents are agreed that there are Specific Factors peculiar to individual tests, both he and his opponents agree that there are Group Factors which run through some but not all tests. Som The componential sub-theory refers to the mental processes through which intelligent behaviour is expressed. There are six products which consist of the form in which information is stored, processed and used; units, classes, relations, systems, transformations and implication. Despite apparent floors in Spearmans model, the notion of g has influenced many theorists since it was first proposed, with several theories having been developed in the wake of Spearmans work.Multifactor theorists argue that there is more than one factor of intelligence to account for. He described g as a kind of mental energy each individual possesses and believed it resulted in our specific abilities and skills (Maltyby, et al.). Stratum I consists of 69 specific levels of intelligence, for example, spelling ability. This argument has been revisited recently by Bartholomew, Deary and Lawn (2009) who concluded that the apparent good fit of a model may not be sufficient to explain the workings of the brain during IQ tests. Carrolls theory incorporates Spearmans g, specific factors, Cattells Gc and Gf, Thurstones group factors and Vernons hierarchical approach (Maltby, et al. Spearman argued that this evidence suggests there is an overall g measured by these IQ tests. Charles Spearman developed his two-factor theory of intelligence using factor analysis. Humphreys (1967), however, does not believe Cattells model adequately explains intelligence and he points to methodological floors in Cattells study, for example, in the selection of variables. Charles Spearman, an English psychologist, noticed that students who did well in one subject area tended to do well in corresponding subjects.. To explain this, Spearman suggested that each individual test has a specific ability (s) that is tapped, so performance on an arithmetic subtest, for example, depends partly on g and partly on numerical skills (s) specific to the test (Gleitman, 1995). Spearman's work on intelligence resulted in A Measure of "Intelligence" for Use in Schools (1925) and The Abilities of Man, their Nature and Measurement (1927).