Sony could detect PlayStation users based on how they hold a controller
A recent Sony patent application identifies a problem many console gamers may be able to identify with when moving between consoles: "To log in to their account a user is often required to enter a password, which may be seen by other users. Moreover, once a user has entered their password, a situation arises where the user remains logged into their account unless the user subsequently performs a log out operation, which can result in other user's [sic] potentially obtaining access to the user's profile."