1. A method of providing user-specific interaction, the method comprising: receiving image content through a television (TV) network; displaying the image content on a digital television; identifying an object of interest of a user among at least one of a plurality of regions and a plurality of objects included in the image content; and providing additional information corresponding to the object of interest, wherein the digital television analyzes signals of a plurality of user devices, converts additional information corresponding to the analyzed signals to be appropriate for the user devices, and provides the converted additional information to the user devices, wherein the signals received from the user device comprise at least one of a vital signal of the user detected by the user device and an external force applied to the user device.