text: This is being done to a limited extent in vision research-People have had microelectrode arrays implanted on the surface of the visual cortex of the brain, connected to a video camera.  The signal from the video camera activates the visual cortex, and these people, many of who have no eyes at all, or totally destroyed optic nerves, are able to "see" simple objects.  Thus, it is a proven concept that electrical signal can feed in meaningful information, and that information can lead to behaviour changes.  For many years, simple electrodes have been used to elicit specific tastes, memories, musclular twitches, etc.  As to your specific question-in order to control people's behaviour..in other words to overcome their will and wishes, and make them do things, or think things, that the operator of the machine wishes, would require a very good understanding of what controls our actions, emotions, and thoughts.  It's very unlikely that we will be at that state in 10-20 years.  Perhaps in 50 years we will have a very basic understanding, and in 100 years a fairly good understanding.  At any rate, when we do understand that, then it would be a relatively simple step to control it electronically (since electronics is simpler than the brain, and would also be advancing over that 100 years).