Knower–guesser differentiation in ravens: others' viewpoints matter

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 278; no. 1705; pp. 634 - 640
• Main Author: Bugnyar, Thomas
• Format: Journal Article
• Language: English
• Published: England The Royal Society 22.02.2011
• Subjects: Animal feeding behavior; Animals; Association Learning; Caching; Chimpanzees; Competitive Behavior - physiology; Competitive Food Retrieval; Corvus corax; Crows - physiology; Curtains; Discrimination Learning - physiology; Feeding Behavior - physiology; Female; Food access; Humans; Knowledge Attribution; Male; Memory - physiology; Mind; Observation; Perspective; Primates; Raven; Ravens; Social behavior
• ISSN: 0962-8452; 1471-2954; 1471-2945; 1471-2954
• DOI: 10.1098/rspb.2010.1514

Differentiating between individuals with different knowledge states is an important step in child development and has been considered as a hallmark in human evolution. Recently, primates and corvids have been reported to pass knower–guesser tasks, raising the possibility of mental attribution skills in non-human animals. Yet, it has been difficult to distinguish ‘mind-reading’ from behaviour-reading alternatives, specifically the use of behavioural cues and/or the application of associatively learned rules. Here, I show that ravens (Corvus corax) observing an experimenter hiding food are capable of predicting the behaviour of bystanders that had been visible at both, none or just one of two caching events. Manipulating the competitors' visual field independently of the view of the test-subject resulted in an instant drop in performance, whereas controls for behavioural cues had no such effect. These findings indicate that ravens not only remember whom they have seen at caching but also take into account that the other's view was blocked. Notably, it does not suffice for the birds to associate specific competitors with specific caches. These results support the idea that certain socio-ecological conditions may select for similar cognitive abilities in distantly related species and that some birds have evolved analogous precursors to a human theory-of-mind.