In seeking to develop a culture-fair intelligence or IQ test that separated environmental and genetic factors, Raymond B. Cattell

Raymond Cattell

Raymond Bernard Cattell was a British and American psychologist, known for his exploration of many areas in psychology...

 created the CFIT or Culture Fair Intelligence Test. Cattell argued that general intelligence (g) exists and that it consists of fluid intelligence and crystallized intelligence

Fluid and crystallized intelligence

In psychology, fluid and crystallized intelligence are factors of general intelligence originally identified by Raymond Cattell...

. Unlike other tests, which typically use a deviation of 15 or 16, Cattell uses a deviation of 24. This means if same normally distributed population took both tests, the central 68.2% would fall between 76 and 124 on Cattell but 85 and 115 on Stanford Binet 5 (deviation 15).

• Crystallized intelligence (gc) refers to that aspect of cognition
  Cognition
  In science, cognition refers to mental processes. These processes include attention, remembering, producing and understanding language, solving problems, and making decisions. Cognition is studied in various disciplines such as psychology, philosophy, linguistics, and computer science...
  
   in which initial intelligent judgments have become crystallized as habits.
• Fluid intelligence (gf) is in several ways more fundamental and shows in tests requiring responses to entirely new situations.