Louis Guttman, a U.S. psychologist proposed this theory of intelligence. The theory states that the organization of mental ability can be represented by a radial order of complexity. There are two parts to the model: A) a simplex which is the relative distance from the center of a circle. Abilities that are closer to the center of the circle are closer to the construct of "general" intelligence Which is dead center on the model circle) and B) a circumplex which represents the relative distance around the circumference of the circle with abilities more highly correlated and thus closer together. the system identifies abilities through a set of coordinates.
RADEX THEORY OF INTELLIGENCE: "The radex theory of intelligence is a graphic model."