ABSTRACT
This chapter examines some of the important psychological, physiological and other theories that have proven themselves important in practice, and sets the background for getting to the deep truth. Sigmund Freud identified what he regarded as the main drivers of human behaviour: eros or libido, which centre on life's pleasures and erotic thought, and thatanos or death instincts. Freud suggested that unconscious emotional responses always occur ahead of conscious reactions to the same input, but may be repressed before intruding into awareness, concealed by mental constructions or through obsessive behaviour, such as repeated washing of the hands or cleaning of the carpet. Freudian theories thus suggest that to succeed with deception, a liar has to block out damaging information from his subconscious, especially his real memory, feelings and attitudes. When interviewed, the liar may deliver his answers too quickly or have varying response times that do not correspond with the complexity of the question or matter concerned.
