Koch investigates metonymically-induced changes of meaning. He makes use of the conceptual networks provided by frame theory. Frames may be seen as conceptual gestalts and, in metonymic changes of meaning, a new sense is highlighted as the figure while the old sense serves as its ground within the frame. Figure/ground effects also account for the origin of metonymy in discourse. Koch distinguishes between three types of ad hoc metonymic innovation inducing a metonymic change: hearer-based inferential innovations such as the interpretation of 'fireplace' as "fire", speaker-based imprecise innovations such as the sense of "hip" for 'thigh,' and expressive innovations such as 'skull' for "head". (Klaus-Uwe Panther and Günter Radden)