Many territorial songbirds alter the structure of their songs after listening to and interacting repeatedly with the same neighbors. Here, we use a robotic lizard to test for similar learned changes in signal structure in male Sagebrush lizards, Sceloporus graciosus. Subjects were exposed to two types of headbob displays (species-typical and unusual) both in short-term tests and in repeated exposures for 10 d. We found no evidence for immediate changes in signal structure to match a particular opponent (signal matching) or long-term changes after repeated exposure (‘song’ sharing). If anything, the lizards’ displays became less like that of the robotic stimulus over time. Further tests of other taxa are needed to identify the evolutionary forces that lead to these forms of behavioral plasticity and to determine whether song sharing and signal matching are unique characteristic of songbirds. Lizards also became more agitated and produced more highly aggressive displays of their own when confronted with headbob displays that violated the basic syntactic structure of their display system, confirming that they were paying attention to subtle differences in display structure despite the artificial nature of the treatments. Thus, our study also adds to the growing evidence supporting the use of robotic playbacks to study animal communication.