When economists first started playing this game in the early 1980s, they assumed that this elementary exchange would always generate the same outcome. The proposer would offer the responder approximately $1⎯a minimal amount⎯and the responder would accept it. After all, $1 is better than nothing, and a rejection leaves both players worse off. Such an outcome would be a clear demonstration of our innate selfishness and rationality.
The X’s marked areas where Kiehl had discovered abnormally low grey matter density in Dugan’s brain. In a curious meeting of law and neuroscience, those X’s would help jurors decide whether he should be executed or sentenced to life in prison. Did the way Dugan’s brain had developed leave him spring-loaded for violence? Or had he chosen freely when he abducted, raped and killed a 10-year-old girl in 1983?