Developmental Accounts of Theory-of-Mind Acquisition: Achieving Clarity via Computational Cognitive Modeling

Developmental Accounts of Theory-of-Mind Acquisition: Achieving Clarity via Computational Cognitive Modeling Paul Bello (Paul.Bello@rl.af.mil) Air Force Research Laboratory - Information Directorate 525 Brooks Rd. Rome, NY 13441 USA Nicholas Cassimatis (cassin@rpi.edu) Rensselaer Polytechnic Institute - Dept. of Cognitive Science 110 8th St. Troy, NY 12180 USA interpreted in variety of ways to suit different purposes. This has several important consequences for the theoretical impact of ToM experiments: Abstract People’s ability to predict and explain the beliefs, desires and actions of others, often called their Theory of Mind (ToM) is an central component of cognition. There is ample experimental evidence suggesting a major developmental shift in children’s ToM somewhere between the ages of three and five (Wellman, Cross & Watson 2001). These results are often interpreted in terms of children acquiring rich understanding of belief and its representational nature. Both of these descriptors are am- biguous and controversial. This makes evaluating the evidence of such a shift, and its implication about the knowledge and mechanisms underlying ToM more difficult. Computational cognitive models are precise by nature, and can help resolve many of these difficulties. We present Polyscheme/ToM, a computational model of human behavior in some important ToM tasks. It uses a domain-general mechanism for repre- senting alternate states of affairs in order to represent the way other people view the world. We demonstrate that the model has several implications: 1) it is possible to succeed in false belief tasks without explicitly representing beliefs; 2) behav- ior in experiments purporting to show success in false-belief- like tasks at earlier ages require significantly simpler mecha- nisms than success in the traditional false-belief task, and 3) the shift from younger to older behavior in these tasks can be accounted for by small, but highly consequential changes in cognitive mechanisms. 1. Disagreement among various researchers concerning the nature of mental states such as beliefs, desires, and intentions have led to any number of interpretations for both performance and developmental data in accounting for them. Philosophers who have studied these problems for millennia cannot even agree upon precise meanings for these terms, and remain at odds over the general proper- ties these states may possess. For example, do children actually represent the beliefs of other agents (i.e., do they have specific beliefs about beliefs), or do they instead have an overall representation of another person’s perspective on the world without explicitly thinking about the individ- ual beliefs that make up that representation, as researchers such as Josef Perner seem to suggest (Perner 1991). Problems in interpreting ToM experiments Developmental psychologists have designed a number of clever and important experiments to chart out the acquisi- tion of so-called Theory of Mind (ToM) by young children (Liu & Wellman 2004). The central debate among theoretical frameworks for describing the acquisition and nature of ToM is focused differing views on how children might be able to predict the actions of other agents. For example, one these theories characterizes children as “little scientists” who con- struct theories of human behavior through connecting stim- uli, mental states, and actions taken by observable human agents. This framework is often called theory-theory (Gop- nik & Meltzoff 1997). Alternatively, proponents of simula- tion theory subscribe to the assumption that children are able to assume the perspective of other people, and use their own cognitive apparatus for dealing with their perspective of the world as a good first-approximation to that of the person to be simulated (Goldman 1989). The results of many different experiments have been used by proponents of both views to buttress support for their respective positions. However, these results are often presented using terms such as representation, belief, knowledge, simulation and model, all of which can be 2. Disagreements over definition make experimental data difficult to interpret. It is often assumed that the false- belief task as presented in (Wimmer & Perner 1983) is the gold standard for determining whether a child has ac- quired the so-called representational theory of mind, and thus a thorough understanding of beliefs. A meta-analysis conducted in (Wellman et al. 2001) strongly corroborates success on these kinds of tasks with a relatively narrow age range (usually between 3.5 and 5.0 years old). How- ever, there are studies that suggest that younger children (e.g., (Wellman & Bartsch 1988)) and even chimpanzees (Call, Hare, Carpenter & Tomasello 2004) have ToM abil- ities normally only ascribed to older human children. 3. Imprecision makes it difficult to assess the magnitude of development. Without a specific and precise account of cognition, both pre- and post- success on the false be- lief task, it is difficult to assess the magnitude of the de- velopment in children’s thinking that the behavior shift in these tasks represents. Theory-theorists are faced with a fundamental problem of accounting for the induction and adaptation of a large knowledge-base corresponding to a n¨aive theory of human behavior. It is difficult to asses how large of a problem this is without a more precise charac- terization of these theories in both younger and older chil- dren. Simulation theorists aren’t faced with the problem of a large theory, they face a more fundamental set of difficul- ties entailed by their own commitments, partially outlined