However, there are four general categories of signals that people can use to detect both deception and scams, which include signs of nervousness, repression, easy agitation or anxiety, and idiosyncratic sources (von Hippel and Trivers, 2011). Sometimes it's easier to spot when something is wrong. People who are familiar with each other's habits can also detect deception through peculiar signals of nervousness, suppression, and cognitive load, because different individuals reveal their mental states in different ways (von Hippel and Trivers, 2011). For example, if a good friend, family member or colleague can suddenly start having behavioral changes or simply start lying about something, then that person will be able to tell that something is happening.