This volume, 'Animal Cognition in Nature', is the result of an ongoing synthesi s of several ideas that were considered revolutionary, if not heretical, in the 1960s. At that time, animal behavior, whether studied in field or laboratory, by ethologists or psychologists, was generally interpreted as the result of simple processes relating specific stimuli to specific behaviors. Examples from that time include S-R models, sign stimuli, IRMs, etc. Theoretical constructs such as mental representations, memory or attention were avoided. Today, students of animal behavior work in an entirely different atmosphere. This is the result of several developments.