Gary Klein, a psychologist and chief scientist at Applied Research Associates in Fairborn, Ohio, has for the past 25 years studied how people make real-life, critical decisions under extreme time pressure. In his 2009 book Streetlights and Shadows: Searching for the Keys to Adaptive Decision Making (MIT Press), Klein discusses 10 surprising ways effective thinkers deal with ambiguous situations. Staff writer Bruce Bower, who writes on Page 26 of this issue about risk and decisions, recently spoke with Klein about good decision making. What is tacit knowledge and why do you consider it so impo... (p. 32)