A TARDIS gets inside your head. This is essential to its function as it helps the operator to run the ship, translate alien thought patterns into recognisable speech, monitor potential threats and perform many other tasks that help to streamline the lives of its occupants.

All TARDIS units are Psychic and this provides the basis for many of its operating systems, particularly the translation, HADS and Internal Weapon Deactivation systems. For more information see the TARDIS Telepathic Systems (pg.92). The TARDIS will never use this ability to intrude upon private thoughts or to possess or otherwise control others, although it is conceivable that a evil operator could find a way to utilise its psychic circuitry for such purposes.