Raymond Cattell was a British psychologist known for his work in personality theory and psychometrics. He developed the 16 Personality Factor Questionnaire, which aimed to measure various traits that define human personality. Cattell's research emphasized the importance of both surface traits and source traits in understanding individual differences. Cattell also contributed to the field of intelligence testing, proposing the distinction between fluid intelligence and crystallized intelligence. His work laid the foundation for further research in personality assessment and has influenced various psychological practices and theories, making him a significant figure in psychology.