Abstract: A touch sensitive apparatus comprises: a top plate comprising a plurality of touch detection regions, and having one or more light sources associated therewith, such that light from the one or more light sources is transmitted within the top plate with total internal reflection; a plurality of detectors for detecting light from the one or more light sources, wherein each detector is associated with a touch detection region; wherein the top plate and the detectors are arranged such that if an external body touches a first surface of the top plate in a touch detection region, then light is coupled from a second surface of the top plate to the associated detector(s); the touch sensitive apparatus further comprising processing means to determine at least the presence or absence of a touch in any of the touch detection regions of the top plate.