This study describes metonymic argument alternations, in which a constructional slot can be filled by any of a set of semantic roles that index one another, and provides a diachronic corpus analysis of two such alternations in French. In the Reveal secret frame and other communication frames, the Medium can indexically replace the Speaker and the Topic can indexically replace the Information. A regression analysis shows that while topic for information metonymy is more syntactically and pragmatically restricted, medium for speaker metonymy has seen an increase in usage over time across the frame. This change is related to sociocultural developments and has implications for the study of figurative language and lexical semantic change. While it is well understood that figurative mechanisms such as metonymy affect language change, here it is demonstrated that cultural shifts drive changes in metonymies themselves, with corresponding impacts for linguistic structure.