1. A system comprising: at least one processor; a head-mountable display that provides a wearer field-of-view when worn; a touch interface arranged on the head-mountable display such that the touch interface is outside of the wearer field-of-view when the head-mountable display is worn; a non-transitory computer readable medium; and program instructions stored on the non-transitory computer readable medium and executable by the at least one processor to perform functions comprising: providing, on the touch interface, a user-interface comprising a set of input areas, wherein each of the input areas is associated with a character from a set of characters; receiving, on the touch interface, first touch input data indicating a selection of a first input area from the set of input areas and a direction relative to the first input area; determining a first subset of input areas from the set of input areas, wherein the first subset includes a range of one or more adjacent input areas extending from the selected first input area in the indicated direction relative to the selected first input area; receiving, on the touch interface, second touch input data indicating a sequence of one or more successive selections of respective second input areas from the set of input areas and respective directions relative to each selected second input area, wherein each selected second input area is located to a first side of a previously selected second input area; determining one or more second subsets of input areas from the set of input areas, wherein each second subset includes a range extending from the selected second input area in the indicated direction relative to the second input area, wherein the range is exclusive of input areas that are located to a second side of previously selected second input area, and wherein the second side is opposite the first side; determining a word that includes respective characters corresponding to input areas within the first subset of input areas and the one or more second subsets of input areas; and causing a visual depiction of the determined word to be provided on a head-mountable graphical display.