Mental states, such as thinking and remembering or feeling angry, happy, or dizzy, have a clear internal component. Barsalou (1999) proposes that introspective experiences are simulated when people understand conceptual references to these mental states. However, mental states can also be described from an external perspective, in which not an inner experience, but an external expression or action may be simulated. In a paradigm based on the property verification task, we presented sentences describing mental states (i.e. emotional, visceral and cognitive states) and contrasted sentences with an internal or external focus. Results show that switching costs occur when participants shift between sentences with an internal and external focus, suggesting that different forms of simulation underlie understanding these sentences. In addition, these findings also imply that references to very different categories of mental states are grounded in a similar way; through the process of simulation.