In the 90's I had a Visual Basic addon which was an AI that monitored the keyboard typing pattern. It could identify who was typing at the keyboard, so you could use it as a backup to lock the system if someone had discovered the password. That app could also be used to encrypt files independently, and only decrypt files when the typing pattern matched the username and password.

Not the only thing which could be used to decide if someone is the genuine user, some users might have tic's like tourettes, but involve unusual mouse movements or clicks. Or they could be things like having to switch on the NumLock on a keyboard in order to type in a numerical password. These are all very subtle behaviours which might not be spotted by someone after the password to get into a system.

Edit So windows has had AI built into its gui since at least Windows 200, really noticeable in XP, its the benign sounding Mouse Properties "Enhance pointer precision", but this can also be used to work out who is using the windows GUI by comparing the operation of the GUI, things like do windows get resized or maximmised, do some programs tend to be use on a particular monitor (if a multimonitor setup), and how on target is the user when closing a window, ie where do they consistently hit the big red X close button in the top right of a window and how quickly do they do this. All this is meta data to further workout who is actually using the computer or not. Linux AFAIK doesnt have this so you have more privacy with Linux in some respects.