``Head Games'' requires a thinking cap for viewers and on-screen subjects, both of whom are challenged with brain games, mind puzzles and social experiments. The human brain is a deeply complex organ, but how does it actually dictate behavior or make a person react to uncomfortable and/or confrontational situations? To find out, experiments are set up throughout the three-part series to see the ways in which everyday people act, conform, and make moral choices when in real-life situations. The experiments are supplemented by games, puzzles and analysis by experts in human behavior. Actor John Krasinski narrates.