Theory of mind abilities in chimpanzees (Pan troglodytes)

: attribution and intentional manipulation of mental states in social problem-solving scenarios

Abstract

Theory of mind, the ability to attribute mental states to oneself and others, is fundamental for our daily social interactions, being at the core of human unique forms of communication and culture. To comprehend how humans acquire theory of mind abilities and which cognitive mechanism are behind it, it is fundamental to investigate its evolutionary origins through the study of theory of mind in other animals, especially in non-human great apes because of their phylogenetic proximity to humans. In this thesis, I have mainly focused on the study of theory of mind abilities in chimpanzees, one of our closest living relatives. In three empirical studies, I have investigated attribution and intentional manipulation of mental states in different social problem-solving scenarios that involve cooperation and competition with conspecifics.

The first chapter of this thesis offers an overview of the ontogenetic development of theory of mind abilities in children, before examining the experimental evidence of theory of mind abilities in apes. Chapter 2 assesses whether chimpanzees and orangutans use understanding of others’ visual perspective to provide their partners with information about hidden food in a mutualistic cooperation task. Chapter 3 explores chimpanzees’ use of theory of mind abilities and manipulation of epistemic states in a competitive task where subjects can employ concealment and distraction deceptive strategies by manipulating external objects. Chapter 4 tests chimpanzees’ explicit false belief understanding and manipulation of belief states in a novel task where subjects have active participation and the possibility to deceive competitors by creating a false belief in them. Overall, apes show remarkable cooperative, communicative and deceptive abilities. They are able to use external objects to request specific actions from conspecifics or prevent them access to food and they predict competitors’ behavior through understanding of visual perspective and knowledge-ignorance states. However, apes do not show understanding of false belief states and, although they are able to use their theory of mind abilities to manipulate others’ behavior, across studies there is no conclusive evidence that apes intentionally manipulate others’ mental states. Finally, Chapter 5 discusses the implications of the findings of the three empirical studies and suggests directions for future research.

Date of Award	2 Jul 2021
Original language	English
Awarding Institution	University of St Andrews
Supervisor	Josep Call (Supervisor)