The evolution of metacognitionThe top flank of Apollo's temple in Delphi reads, "Know Thyself." It is not surprising that such an adage is associated with the favored son of the Olympian god, Zeus, the god of light, arts and sciences, and humanity's greatest aspirations. Indeed, the association between Apollo and philosophy make it clear that for the ancient Greeks, self-awareness and self-reflection were essential for existence. This sentiment is best captured by another renowned Greek, Socrates, who famously asserted that, "an unexamined life is not worth living."
This tradition was elaborated and extended by a number of leading philosophers of the Enlightenment, the most notable of which was Descartes (1637). Descartes' philosophy, like that of Socrates, highlighted the importance of both self-awareness and selfreflection to our understanding of being human. In fact, for Descartes knowing oneself and asserting, "I think therefore, I am" was the only way to prove one's existence.
The questions we hope to answer in the proposed experiments are in step with this centuries-old tradition of self-exploration. The unique contribution of this proposal will be to explore these same questions in a comparative framework where the differences and similarities between human and non-human primates will be systematically explored. The proposed experiments are of particular interest because Descartes and many others since have maintained that animals are unable to engage in the kind of self-reflection that led to the adage of "I think, therefore, I am" because animals lack the ability to communicate using language,
For it is very noticeable that there are no human beings, not the unintelligent or stupid, including even mad people, who are incapable of arranging different words and composing from them an utterance by which they make their thoughts understood; whereas there is no other animal, no matter how perfectly and favourably born it may be, which acts similarly. (Descartes, 1637) Translation by Desmond M. Clark, Penguin Books (1999) p. 41.
Descartes argued that animals' behavior consists of instinctive and mechanical reactions to their environments. In contrast, the fluent use of language by humans was taken as both evidence for self-reflective consciousness and proof that only humans have it. Though a number of studies that have attempted to train apes how to use language have failed, animals have, nonetheless, shown intelligent behavior in the absence of language in a number of studies. Some of these experiments include monkeys making logical inferences in the form of if A > B and B > C then A > C and developing expertise about a similar problem when tested with novel exemplars (Cheney & Seyfarth, 1990; Terrace
et al., 2003).
Various studies conducted in our laboratory have indicated that monkeys are sensitive to their lack of knowledge when confronted with a novel (and a difficult) problem. This sensitivity has been demonstrated in two studies. In one, monkeys asked for a "hint" when presented with a difficult problem. In a second, nave monkeys, when given the opportunity, appreciated the fact that they could solve a problem faster if they studied the actions of an expert model than if they attempted to solve the problem entirely by trial and error (Subiaul
et al., 2004).
The proposed experiments build on these earlier findings. Specifically, we hope to demonstrate that, though animals lack a linguistic form of communication, they nevertheless possess the ability to reflect on their own knowledge-state and act accordingly. Results from these studies have the potential to make a number of significant contributions to philosophy, psychology, and the evolutionary sciences. These results will have clinical and educational applications, as well. Foremost, these studies will help us understand the basic processes primates in general use to guide their behavior when presented with difficult problems. Do subjects who are confronted with difficult problems seek out information? Do they ask for more time to study a given problem? Or, do they seek out information from a knowledgeable conspecific either indirectly-by studying the model's responses-or directly-by requesting specific information necessary to solve the problem? Critically, because the proposed experiments will use the same task and analogous procedures across subjects, we will be able to compare performance between species. As a result, we will be able to ask the following questions: Can differences between human and non-human primates on metacognitive tasks be explained by language? Is an understanding of the mental states of others (i.e., a theory of mind) an intervening variable when trying to understand one own's mind? Or is the ability to form representations of the contents of one's own mind independent of the ability to form representations of the contents in the minds of others?
To date, all experiments on metacognition have focused on understanding different aspects of the system in humans. Some studies have begun to explore related phenomena in non-human primates, such as monkeys. None have developed a program that compares human and non-human primates in a variety of metacognitive tasks in both social and asocial settings in order to compare what aspects of the metacognitive system are uniquely human and which are shared among primates in general. As a result, the proposed research program in addition to being the first of its kind holds the promise of bringing us closer to better knowing ourselves.
Cheney, D. L., & Seyfarth, R. M. (1990).
How monkeys see the world. Chicago: University of
Chicago Press.
Descartes, R. (1637).
Discourse on method.
Subiaul, F., Cantlon, J., Holloway, R., & Terrace, H. (2004). Cognitive imitation in rhesus macaques.
Science, 305, 407-410.
Terrace, H. S., Son, L., & Brannon, E. (2003). Serial expertise of rhesus macaques.
Psychological
Sciences, 14(1), 66-73.
