1 Simulation article SIMULATION Alvin Goldman and Kelby Mason To appear in: Handbook of Philosophy of Psychology and Cognitive Science (Paul Thagard, ed.) Abstract Simulation theory is a prominent account of how people engage in mindreading. Problems are presented for the rival theories, including rationality theory and theory theory (both child-scientist and modularity versions). The conceptual change approach to young children’s difficulties with false-belief tasks is shown to be dubious. Mirror neurons demonstrate the existence of simulation, or resonance, mechanisms by which mental states in an acting agent are replicated in an observer. When one merely observes another individual execute an action, a matching action plan is activated in one’s own brain. Similar mirroring systems are found for touch, pain, and disgust. Evidence that such simulation mechanisms are used for mindreading is found in impairments of face- based emotion recognition. Evidence for higher-level simulation-based mindreading is discussed, based on patterns of egocentrism, or projection. Key Words Child-scientist theory, Curse of knowledge, Egocentrism, Emotion recognition, Empathy, False-belief task, Folk psychology, Inhibitory control, Mindreading, Mirror neurons, Motor imagery, Projection, Rationality theory, Simulation theory, Theory of mind, Visual imagery 1. Introduction Human beings spend a lot of time thinking about thoughts, feelings and other assorted mental states, both their own and those of others. I try to figure out what Albertine really thinks of Oscar, how much a certain gift would please the intended recipient, how I would feel in the morning if I had another drink. We commonly arrive at beliefs about such mental states, and thereby make attributions--retrospective, concurrent or predictive attributions--to the persons in question, the “targets” of attribution. The psychological capacity to perform this kind of task is variously referred to as mindreading, folk psychology, theory of mind or mentalizing. This capacity makes an appearance early in life, across cultures and without explicit cultural instruction. Most of our everyday social interaction and communication seems to depend on our beliefs and expectations about the mental states of other people, and therefore on mindreading. The scientific study of mindreading began with a paper in primatology. Based on the impressive performance of chimpanzees on various tasks, David Premack and Guy Woodruff (1978) argued that they had humanlike mindreading abilities (see Tomasello and Call 1997, Heyes 1998, and Povinelli et al. 2000 for more sceptical reviews of 2 Simulation article mindreading in non-human primates). The tasks they used, however, could not rule out the possibility that chimpanzees were merely exploiting correlations between situations and targets’ behavior (e.g. when food is around, others will eat it), rather than actually thinking about targets’ mental states (e.g. that others want the food and will therefore eat it). This prompted several philosophers (Dennett 1978, Harman 1978) to suggest a more rigorous test for mindreading, the false-belief task (described below). The false-belief task was introduced to developmental psychology in an influential paper by Heinz Wimmer and Josef Perner (1983), who tested for infants’ mindreading abilities. Since then, mindreading has become a major area for research in philosophy and the cognitive sciences, including developmental psychology, social psychology and neuroscience. One theory of mindreading is that it involves mental simulation. Its basic idea is that in predicting the target’s mental states, we try to simulate or reproduce in our minds the same state, or sequence of states, that they are in. We put ourselves in their position, and see what we would believe, feel or do. There are various ways to elaborate this basic idea, and there are also alternative accounts of mindreading. To give some idea of the context in which simulation theory emerged, we sketch these alternative accounts below. But the main focus of this chapter is simulation, and so we give more attention to versions of simulation theory, detail the evidence for the importance of simulation, and discuss some of the key conceptual issues for simulation theory. A comprehensive theory of human mindreading should address at least the following six questions: 1. How do we mindread other people? What processes do we use to arrive at mental state attributions? 2. How do we mindread ourselves? (Since the processes of first- and third- person attribution may differ, this is a separate question from (1)). 3. The developmental question—how and when do we acquire the capacity for mindreading? 4. The architectural question—how is this capacity implemented in the brain, and how is it connected with other capacities? 5. The conceptual question—what is the content of the mental state concepts used in mindreading? 6. The comparative/evolutionary question—what are the mindreading capacities of other species, and how did the human capacity evolve? Although there are connections between these questions, especially (1) and (2), they are still largely independent. Simulation theory is primarily an answer to (1), and only secondarily to the others. Similarly, the chief alternative to simulation theory, theory theory, is in the first instance a theory about the process of third-person attribution. In the next section we outline the basics of the theory theory of mindreading, as well as two other accounts that have been suggested as alternatives to simulation theory, namely modularism and rationality theory. 3 Simulation article 2. Alternatives to simulation Theory theory According to theory theory, our mindreading capacity is implemented by an intuitive theory of mind, a body of knowledge or belief about the causal relations between mental states on the one hand and behavior, environment and other mental states on the other. An intuitive, or folk, theory of mind is supposed to contain a lot of generalizations like the following: 1) If someone wants x, and believes that y is a means to x then, other things being equal, they will do y 2) If someone believes p and if p then q then, other things being equal, they will believe q 3) If x is in someone’s field of vision and they are attending to the scene then, other things being equal, they will perceive x In mindreading, we use these generalizations and our data about the target’s circumstances or behavior to infer some of the target’s mental states. Once we have done this, we can then make further predictions or retrodictions about their other mental states. Note that neither the theory of mind nor the process of inference is assumed to be accessible to consciousness. Thus we can be mostly unaware of either its principles or any overt deductive or inductive inferences, while still relying on them at a subpersonal level when we mindread. In addition, the generalizations of theory of mind would need to be much richer and more complicated than the skeletal folk platitudes (1)-(3), but theory- theorists have done limited work on formulating more realistic principles. In the early days of research on mindreading, theory theory was the default account of mindreading in psychology (and to some extent it still is). This is partly due to the prevalence in philosophy of mind of a position called functionalism (Lewis 1972; Block 1978; Shoemaker 1984). According to one brand of functionalism, common sense functionalism, mental-state concepts are understood in terms of their role (or function) in the overall cognitive economy. What we understand by a mental state such as pain or belief, say, are the causal links between that state and behavior, environment and other mental states, links that are specified by a common sense psychological theory. If mental states are understood by their functional roles in a common sense psychological theory, then it is natural to infer that when ordinary people are thinking about mental states—as in mindreading—they apply such a theory. This functionalist notion of “theory” is one of several reasons for calling the body of our folk-psychological knowledge a theory. Just as in many scientific theories, folk- psychological concepts like belief and desire are interdefined by a cohesive set of causal principles. Moreover, setting aside the controversial status of introspection, mental states are not directly observable, and in other scientific domains such non-observable entities (e.g. atoms, genes) are often called “theoretical”. Finally, if mindreading involves making inferences from observable data and general principles, then it resembles 4 Simulation article scientific processes of prediction. Because it holds that mindreading requires a lot of propositional knowledge like (1)-(3) plus inferences from this knowledge, theory theory can also be called an information-rich and inferentialist approach. In its most general form, theory theory is a theory about the process of mindreading. As such, it is compatible with a variety of views about the development of mindreading, its cognitive architecture, and the relation between first- and third-person mindreading. The purest form of theory theory, however, takes a definite stance on the first three of these questions. This is the child-scientist theory, advocated by Alison Gopnik, Henry Wellman, and Andrew Meltzoff (Gopnik and Wellman 1992, 1994; Gopnik and Meltzoff 1997). According to the child-scientist theory, the resemblance between our mindreading capacity and scientific