Why do people ignore security warnings? Why do they pay attention to some advice but ignore others? Why are spammers and phishers apparently so good at getting people’s attention? Over the course of each day, we often receive dozens of warnings. We’re told that web sites are using untrusted certificates, that downloads might harm our computers and that scripts may be unsafe. We’re so used to these warnings that we hardly even notice them anymore. But what makes an effective warning message? Why do people stop and consider some messages but happily ignore others?