Theory of Mind in Bonobos: Sponsored Student Research Project 2019–2020
Makesha Balkaran
MHC Philosophy Honors (B.A.), MHC Psychology Honors (B.A.)
Class of 2021
Vincent M. Andreassi
Philosophy and Cognitive Science (B.A.), Linguistics and Neuroscience (B.A.)
Class of 2020
Do great apes have a theory of mind (i.e., the ability to attribute mental states to themselves and others)? This is a longstanding question in primatology that has important philosophical implications for the question of human uniqueness and the origin of human culture. Philosophy majors Makesha Balkaran and Vincent M. Andreassi participated in a research project sponsored by the Philosophy Department that aimed to answer this question. Makesha and Vincent describe their research projects below.
Due to our background interests and experiences in the fields of philosophy and psychology, we [Vincent M. Andreassi and Makesha Balkaran] were selected to participate in a theory-of-mind research project with bonobos (a species of great ape) proposed and directed by Professor Robert Lurz, chair of the Philosophy Department. This research opportunity was supported through the Philosophy Department's Jay Newman Fund and authorized by the Jay Newman Chair of the Philosophy of Culture, Professor Serene Khader. We wish to thank Professor Lurz and Professor Khader for giving us this unique and special opportunity to participate in research on theory-of-mind abilities in bonobos.
We know that humans are influenced by what we think others believe. Is this something unique to the human mind or are other animals also influence by what they think others believe? Our research projects were aimed to test whether a bonobo, named Kanzi, would be influenced by what he thought another agent believed. Bonobos are a species of great ape, and one of our closest living nonhuman relatives. If bonobos have a theory-of-mind like humans, we predicted that Kanzi's behavior in the test should be influenced by the different beliefs of another agent. To test this, we each designed separate touch-screen tests for Kanzi to be administered to him at the Ape Cognition and Conservation Initiative (ACCI) in Des Moines, where Kanzi lives. The tests were non-invasive, caused Kanzi no harm or stress, were approved by ACCI's and Brooklyn College's IACUC, and were part of his regular enrichment program.
Makesha's Project
In this study, we designed a touchscreen video test that recorded how fast Kanzi responded to a prompt in a video he watched. Kanzi watched a video of a banana being hidden in one of two containers (which container the banana was hidden in Kanzi couldn't see). However, in the video, a person (the communicator) pointed to the container with the banana inside and said "Kanzi, the banana is in here." Kanzi was rewarded with a grape if he touched the container (on the screen) to which the communicator pointed. The computer program we used recorded how long it took Kanzi to point to the onscreen containers. In some of the videos, the communicator knew (correctly believed) which container had the banana inside (true-belief test), while in other videos the communicator had a false belief about which container had the banana inside (false-belief test). If Kanzi was influenced by what he thought the communicator believed, we predicted that Kanzi should be slower to touch the container to which the communicator pointed in the false-belief test than in the true-belief test. Data for my test is still being collected at the moment.
This research opportunity provides an insight into the function of cognition in non-human brain functioning—and for that matter, explores how cognition diversely evolves. As a student of Brooklyn College, this research, therefore, allows the special chance to expand my range of being able to think empirically, by developing and testing hypotheses regarding the world; and in this case, the research provided me the opportunity to investigate the evolutionary orgins of theory-of-mind in humans and great apes by using information gathered from one of our closest living relative, the bonobo.
Vincent's Project
This study was similar to Makesha's study except that the communicator (who indicated where the banana was hidden) was replaced by a guy in a gorilla suit (played by Professor Lurz) who wanted to take the banana away from where it was hidden. Kanzi watched videos in which the "gorilla" was shown trying to steal a banana on the table before it was placed into one of two containers. Kanzi's tasks was merely to touch the container that he saw that banana go into. In some of the videos (true-belief test), the gorilla knew (had a true belief) which container the banana was in; while in other videos (false-belief test), the gorilla had a false belief about which container the banana was in. Does Kanzi attribute to the gorilla a false belief about the banana's location? We hypothesized that the discrepancy between what Kanzi believes (about which container had the banana) and what the gorilla believes (about which container had the banana) in the false-belief test, should result in a delayed response in this test condition relative to the true-belief test. Thus, we predicted that if Kanzi has a theory of mind, he would react more slowly in the false-belief test than in the true-belief test.
Early data suggest Kanzi indeed reacted more slowly in the false-belief test than in the true-belief test. Kanzi was on average 88 milliseconds slower in the false-belief test than in the true-belief test. We are in the process of collecting more data with a second subject.
This research opportunity has been of great value to me as students here at Brooklyn College, allowing me to gain hands-on experience in the nuts and bolts of experimental design and problem-solving creatively as a team. My philosophical perspectives on cognition and theory-of-mind have deepened as a result, as has my appreciation for how the study of non-human animals can inform our understanding of human cognitive function and evolution.
