1. Cognitive Ethology Laboratory, German Primate Center, Kellnerweg 4, 37077 Goettingen, Germany
2. Leibniz ScienceCampus Primate Cognition, Kellnerweg 4, 37077 Goettingen, Germany
3. Department for Primate Cognition, Georg-August-University Goettingen, Kellnerweg 4, 37077 Goettingen, Germany