In the framework of a longitudinal case study on a male tervueren dog, Philip, the present paper was aimed to get a more sophisticated insight into the cognitive functioning of the dog's mind. Our experiment was designed to study the dog's ability to recognize knowledge or ignorance in others. The procedure used here was identical to that used in an ape-study (Gómez & Teixidor, 1992) and therefore provides the possibility for direct dog-ape comparison regarding their performance. Results show that similarly to the case with this “enculturated” orangutan, after few trials Philip was able to adjust his communicative behaviour to the state of knowledge of his human partner and cooperated successfully in the problem solving task (getting the ball). The exact mechanism underlying this communicative behaviour is still not clear, and both low- and high-level explanations are considered. We suggest that this approach gives a new possibility to conduct comparative studies aimed to understand the evolution of social cognition
