G Factor or General Intelligence
Is intelligence a singular factor or does it have several facets? In scientific circles the discussion is lively and ongoing. The British scientist Charles Spearman postulated that there is one dominant general intelligence factor (also called the G factor), that governs all cognitive abilities.
Not everybody agrees. Some claim that there are multiple intelligence factors, which are (more or less) independent. According to these scientists, a person could for example be very good at math, but very bad in memory related tasks.
Fluid intelligence and crystallized intelligence
A very important distinction between intelligence factors is the one between 'fluid intelligence' and 'crystallized intelligence'. Fluid intelligence refers to the degree of flexibility in thinking and the ability to reason abstractly. Crystallized intelligence refers to the degree in which an accumulation of knowledge and skills has taken place in the course of life.
Fluid intelligence is influenced by environment and learning experiences to a much less degree than crystallized intelligence. The first form of intelligence is to a larger degree a reflection of the genetic component of intelligence.
Read more on multiple intelligences or take an IQ test.