Answer by taking a quote from the following article:

Herman Melville (August 1, 1819 - September 28, 1891) was an American novelist, short story writer, and poet of the American Renaissance period. His best known works include Typee (1846), a romantic account of his experiences in Polynesian life, and his whaling novel Moby-Dick (1851). His work was almost forgotten during his last 30 years. His writing draws on his experience at sea as a common sailor, exploration of literature and philosophy, and engagement in the contradictions of American society in a period of rapid change.

The "Melville Revival" of the late 1910s and 1920s brought about a reassessment of his work. The centennial of his birth was in 1919. Carl Van Doren's 1917 article on Melville in a standard history of American literature was the start of renewed appreciation. Van Doren also encouraged Raymond Weaver, who wrote the author's first full-length biography, Herman Melville: Mariner and Mystic (1921). Discovering the unfinished manuscript of Billy Budd, among papers shown to him by Melville's granddaughter, Weaver edited it and published it in a new collected edition of Melville's works. Other works that helped fan the flames for Melville were Carl Van Doren's The American Novel (1921), D. H. Lawrence's Studies in Classic American Literature (1923), Carl Van Vechten's essay in The Double Dealer (1922), and Lewis Mumford's biography, Herman Melville: A Study of His Life and Vision (1929). Starting in the mid-1930s, the Yale University scholar Stanley Williams supervised more than a dozen dissertations on Melville that were eventually published as books. Where the first wave of Melville scholars focused on psychology, Williams' students were prominent in establishing Melville Studies as an academic field concerned with texts and manuscripts, tracing Melville's influences and borrowings (even plagiarism), and exploring archives and local publications. Jay Leyda, known for his work in film, spent more than a decade in archives and small-town libraries gathering documents and records for a day by day record, published as Melville Log (1951). Sparked by Leyda, the second phase of the Melville Revival emphasized research rather than accepting Melville's early books as reliable accounts. The postwar scholars tended to think that Weaver, Harvard psychologist Henry Murray, and Mumford favored Freudian interpretations which read Melville's fiction too literally as autobiography; exaggerated his suffering in the family; and mistakenly inferred a homosexual attachment to Hawthorne. They saw a different arc to Melville's writing career. The first biographers saw a tragic withdrawal after the cold critical reception for his prose works and largely dismissed his poetry. A new view emerged of Melville's turn to poetry as a conscious choice that placed him among the most important American poets. Other post-war studies, however, continued the broad imaginative and interpretive style. Charles Olson's Call Me Ishmael (1947) presented Ahab as a Shakespearean tragic hero, and Newton Arvin's critical biography, Herman Melville (1950) won the National Book Award for non-fiction in 1951. Hershel Parker published his two volume Herman Melville: A Biography, in 1996 and 2002, based on extensive original research and his involvement as editor of the Northwestern-Newberry Melville edition.

What did he study?
psychology,