Hearst was born in New York City. He won the New York State Chess Championship in 1950 and became one of the best American players during that time. He competed in the U.S. Championship in 1954 and 1961.
In 1960, Hearst was a member of the U.S. Chess team at the World Student Team Championship held in the U.S.S.R. The U.S. team won the championship that year, and is was the only time the U.S. has ever won that event. Hearst was Captain of the United States team at the 1962 Chess Olympiad. During the 1960s he authored the "Chess Kaleidoscope" column for "Chess Life" magazine.
Hearst earned a Ph.D in Psychology in 1956 from Columbia University. He left Indiana University with a Distinguished Professor Emeritus status and became Adjunct Professor of Psychology at the University of Arizona.