Daniel Kahneman, who never took an economics course but who pioneered a psychologically based branch of that field that led to a Nobel in economic science in 2002, died on Wednesday. He was 90.

Portrait of Daniel Kahneman, Israeli-American psychologist and 2002 Nobel Prize winner in economics, at the DLD Conference 2009 in Munich on January 27, 2009. Andreas Mueller/VISUM/Redux New Delhi ...