Four Boston-area residents have been named 2012 MacArthur Fellows and recipients of the MacArthur Foundation’s annual $500,000 “genius grants.”

•Benoit Rolland, 58, has made bows for stringed instruments since 1971. For more than a decade he’s worked from his home studio in Watertown. Besides crafting bows out of Pernambuco wood, he has created high-quality bows out of non-wood composite materials.

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•Junot Diaz, 43, is an author and the Rudge and Nancy Allen professor of writing at MIT. Diaz, a native of the Dominican Republic is best known for writing about the Caribbean diaspora and the transitions of Hispanics to life in the United States.

•Raj Chetty, 33, is a professor of economics at Harvard. Chetty is celebrated for studying the economy through a prism of government policy and exploring how government function and tax policy impact people’s spending and work habits.

•Benjamin Warf, 54, is a pediatric neurosurgeon at Boston Children’s Hospital, where he is credited with developing groundbreaking surgical and treatment techniques for intra-cranial diseases in young children. He has a particular expertise in hydrocephalus, or “water on the brain.”