 These observations provide ammunition for pluralism about representational format. Pluralists can posit one system of compositionally structured mental representations for perception, another for navigation, another for high-level cognition, and so on. Different representational systems potentially feature different compositional mechanisms. As indicated in  section 1.3,  pluralism figures prominently in contemporary cognitive science. Pluralists face some pressing questions. Which compositional mechanisms figure in which psychological domains? Which representational formats support which mental operations? How do different representational formats interface with each other? Further research bridging philosophy and cognitive science is needed to address such questions.