Anthropocentric biases manifest themselves in two different ways in research on animal cognition. Some researchers claim that only humans have the capacity for reasoning, beliefs, and interests; and others attribute mental concepts to nonhuman animals on the basis of behavioral evidence, and they conceive of animal cognition in more or less human terms. Both approaches overlook the fact that language-use deeply informs mental states, such that comparing human mental states to the mental states of nonlinguistic animals is misguided. In order to avoid both pitfalls -- assuming that animals have mental lives just like we do, or assuming that they have no mental lives at all -- I argue for a functional methodological approach. Researchers should study animal cognition by identifying environmental inputs, the functional role of internal states, and behavioral outputs. Doing so will allow for cross-species comparisons in a way that the use of folk psychological terms does not.