Palmists, astrologists, and readers of tarot cards or crystal balls claim to help solve personal problems. Mediums claim to aid communication with deceased friends and relatives. Faith healers and psychic surgeons claim to cure physical illness. Psychic detectives offer advice to law enforcement agencies in hope of solving crimes. Other claimants operate in religious organizations using their alleged ability to help attract new followers or maintain the loyalty of present ones. Is all of this just innocent fun, real help, or can psychics actually harm individuals with their claims?

Deception & Self-Deception outlines many of the techniques that can be used to fake psychic ability and describes ways in which these can be countered during an investigation. Richard Wiseman examines the general principles of deception and how these principles may be used to deceive. He also gives an account of the reliability of testimony related to the performance of alleged psychics and seances.