Emotional language, repetition and a sense of shared values are some of the ways people find common ground in conversation.
They are also methods used by two of the world's most infamous terrorists - Osama bin Laden and the Christchurch mosque gunman - to incite extremist violence.
Charles Darwin University's expert in forensic linguistics, Dr Awni Etaywe says examining their writings can help authorities identify other potential terrorist threats.
Etaywe spoke to Corin Dann.
