Miranda warning
According to the American Psychological Association, people are so used to hearing the Miranda warning on television that they think they understand their rights.  However, a 2011 study by Richard Rogers says that many people do not understand their Miranda rights, or have wrong beliefs about them.  For example, Rogers found that 31% of defendants waiting for trials in Texas and Oklahoma did not understand their right to remain silent.  They believed that if they did not answer questions, the court would use that as evidence of their guilt.  Rogers also found that 36% of college students believed the same thing.