The successful ones exhibit three similar characteristics— psychopathy, narcissism and Machiavellianism —which have been referred to by psychologists as “dark” personality traits. Those characteristics allow con artists to swindle people out of their money without feeling any remorse or guilt.

Konnikova, the author of 2016's The Confidence Game, recently spoke to The Harvard Gazette and revealed the three core traits of a con artist and how to avoid being conned. Konnikova says all con artists share some mixture of three traits: psychopathy, narcissism, and Machiavellianism.