Do rhesus monkeys (Macaca mulatta) attribute knowledge and ignorance to others?

Area of Science:

• Cognitive Ethology
• Primate Cognition
• Theory of Mind Research

Background:

• Understanding mental states, such as knowledge and belief, is crucial for complex social interactions.
• Previous research has explored theory of mind capabilities in various primate species, with mixed results.
• Rhesus macaques (Macaca mulatta) are a well-studied model organism for primate behavior and cognition.

Purpose of the Study:

• To investigate whether rhesus monkeys can infer the causal link between visual perception and knowledge.
• To determine if macaques can differentiate between individuals based on their differing states of knowledge (knower vs. guesser).
• To test the hypothesis that rhesus macaques lack the ability to make inferences about others' mental states.

Main Methods:

• Four rhesus monkeys observed an experimenter who alternated roles as a 'knower' or 'guesser'.
• The 'knower' saw food being hidden under one of three cups; the 'guesser' did not observe the hiding process.
• Monkeys were presented with choices indicated by the 'knower' (correct) and the 'guesser' (incorrect) to assess their discrimination ability.

Main Results:

• None of the rhesus monkeys demonstrated an ability to distinguish between the 'knower' and the 'guesser'.
• The macaques did not use the differing information provided by the two experimenter roles to guide their choices.
• Behavioral responses did not indicate an understanding of the experimenters' distinct levels of awareness.

Conclusions:

• The findings suggest that rhesus macaques may not possess the capacity for inferring others' mental states.
• These results support the hypothesis that rhesus macaques are limited in their ability to attribute knowledge to others.
• Further research is needed to fully elucidate the nuances of theory of mind in non-human primates.