Categorical assignments were problematic. For example, the decision to append cognitive to a body of biological research on neurons, e.g. the cognitive biology of neuroscience, is separate from the decision to put such body of research in a category named cognitive sciences. No less difficult a decision needs be made—between the computational and constructivist[43] approach to cognition, and the concomitant issue of simulated v. embodied[44] cognitive models—before appending biology to a body of cognitive research, e.g. the cognitive science of artificial life.