Do you tend go straight to a certain tab when you first visit PopSci.com? Do you ever navigate using your arrow keys? (Who does this?) If the app notices that a person, while signed into his account, isn't navigating like usual, it can do something about it. For example, it could ask for him to answer security questions. This level of security might not be so crucial for Popular Science, but it's attractive for banking and shopping online. An app based on these techniques could even recognize and repel spambots, the patent suggests.