The document discusses several theories of intelligence, including:
1. Charles Spearman's theory of general intelligence ("g" factor) which proposes one general ability underlies other mental abilities.
2. Louis Thurstone's theory that intelligence comprises separate mental abilities rather than one general factor.
3. Howard Gardner's theory of multiple intelligences which defines eight independent abilities like musical and interpersonal intelligence.
4. Robert Sternberg's triarchic theory that intelligence consists of analytical, creative, and practical abilities.