One of Professor Simon's specialties lies in the field of law & psychology, a subject he teaches at both graduate and undergraduate levels. He is the author of In Doubt: The Psychology of the Criminal Justice Process. The book focuses on the psychological causes of errors in the criminal process, which can readily result in the punishment of innocent people and the acquittal of the guilty. He lectures frequently on psychological insights into the criminal process to judges and law enforcement personnel. Simon also specializes in psychological experimentation in the domains of reasoning and decision making. His work focuses on bi-directional processing, grounded in connectionist models of cognition.