Among his major contributions to psychology are the triarchic theory of intelligence and several influential theories related to creativity, wisdom, thinking styles, love, and hate. A "Review of General Psychology" survey, published in 2002, ranked Sternberg as the 60th most cited psychologist of the 20th century. Sternberg has acquired over $20 million in grants and contracts for his research and has conducted research on five continents. The central focus of his research is on intelligence, creativity, and wisdom. He has also studied close relationships, love, and hatred. He has authored or co-authored over 1,500 publications, including articles, book chapters, and books. His work has been critiqued due to excessive self-citation and self-plagiarism. In 2018 he resigned as the editor of Perspectives on Psychological Science in response to these claims.