Representational development and theory-of-mind computations

[Gop] Cognitive developmentalists often jump on bandwagons. This was the case with Piagetian "conservation" in the 60s and 70s. Hoards of experimental variations on a theme swamped the developmental literature, with little or,no theoretical interest other than to lower the age that correct performance on conservation tasks could be demonstrated (see Karmiloff-Smith 1981 for critical discussion). The latest hot topic of the developmental 80s and 90s theory of mind stemmed from Premack and Woodruff's (1978) seminal BBS target article on the chimpanzee, together with the clever experimental adaptation to human children by Wimmer and Perner (1983). Every developmental journal and conference is now permeated with theory-ofmind experiments. Fortunately, however, this time there are some notable theoretically oriented exceptions to the usual experimental bandwagon, and these have made it possible to explore the biological versus cultural underpinnings of children's knowledge, the modular status of theory-of-mind representations and their impairment in autism, and the status of theory-of-mind knowledge as an explicit theory in the child's mind (Baron-Cohen 1991b; Baron-Cohen et al. 1985; Frith 1989; Gopnik & Wellman 1992; Leslie 1987; Perner 1991b). Gopnik's present target article is another step in this important direction. Gopnik argues that children's understanding of their own beliefs (and other intentional states) is mediated by the same internal representations as their understanding of the beliefs of others and hence that there is nothing "privileged" or "direct" about access to first-person intentional states. She goes on to claim that these common representations take the form of an explicit theory that is directly analogous to a scientific theory. This "theory-theory" (Churchland 1984; Gopnik & Wellman 1992; Stich 1983) is contrasted with a "simulation theory" (Goldman 1989; 1992a; Gordon 1986; 1992c), in which the intentionality of psychological states is gradually developed through experience. This dichotomy leads Gopnik to interpret the developmental evidence as indicating "a dissociation between the psychological states that cause the children's behavior and their sincere conscious report of their psychological experience" (sect. 6, para. 6). Implicit in this view is a claim that the psychological states of children are the same as those of adults; children simply have difficulty in accessing and reporting those states before age 4. Indeed, Gopnik explicitly endorses this claim in describing children's psychological states: "these creatures [children] are not just like us, they are us . a few years ago" (sect. 6, para. 8). We do not fundamentally disagree with Gopnik's general thesis that common representations subserve theory-of-mind processes for both firstand third-person states. However, in this commentary we conceptualize changes in children's theory of mind (as well as changes in expertise) as involving representational change rather than more efficient access. We believe that this provides a more productive view on the nature of development in this area. Furthermore, let us be clear that we endorse the view that theory-of-mind computations involve secondorder or meta-representations (Leslie 1987), that they find their roots in the proto-declaratives of infancy (Baron-Cohen 1991b; Gomez 1991), that the propositional attitudes they involve find an early behavioral manifestation in toddlers' pretend play (Leslie 1987), and that the capacity for meta-representation is specifically human (Karmiloff-Smith 1979a; 1979b). We claim, however, that the developmental pattern of success and failure on theory-of-mind tasks can be better understood in terms of progressive refinement and elaboration of the representations that underlie intentional states, rather than in terms of discrete stages of improvement in access to fully specified representations. In support of her position, Gopnik places great stress on the fact that 3-year-olds can successfully solve a problem in which past knowledge is pitted against present knowledge as long as the past knowledge does not involve mental states but physical states. Thus, 3-year-old children can succeed in an experimental setting where an object is hidden in location A, subsequently moved to location B, and is in B at the moment of questioning about its previous location (the physical location task). Threeyear-olds, however, fail if mental states must be computed, such that one protagonist thinks an object is in location A while the child knows it to have been moved in location B (the mental location task). Children seem unable to attribute the false belief of location to the other protagonist's mind until they are 4 years of age. This has led several authors to invoke a fundamental change in theory of mind at age 4. There are other data, however, that suggest 3-year-olds can attribute false beliefs to other minds under certain conditions and that 4-year-olds cannot under other conditions. In particular, when given the same theory-of-mind task but solely in verbal form (i.e., the child does not see where objects are hidden or moved to but is merely told so), 3-year-olds succeed (Zaitchik 1991). By contrast, when given the task purely in visual form with no verbal input for example, in the form of a silent film (Norris & Millan 1991) 4and 5-year-olds find the task difficult and it is only at close to 6 years that they succeed. It is difficult to interpret this developmental pattern of performance in terms of differential access to equivalent beliefs. If 4-year-olds can access beliefs that are generated from both visual and verbal input (in the standard form of the false-belief task), why should they fail when given only visual input? How can 3-year-olds succeed with only verbal input when they fail on the standard task with both visual and verbal input? Clearly, more is needed to explain the results of these different experiments other than simply differentiating between physical and mental location tasks. Theory-of-mind tasks require the ability to simultaneously represent conflicting information: the protagonist's (or one's own) belief about a past situation and the current true situation. We believe the developmental results are best interpreted in terms of increasing capability in using and generating symbolic representations that are sufficiently well elaborated to override the otherwise compelling interpretations generated by direct experience. Furthermore, language is central to theory-of-mind processes precisely because it provides particularly effective "scaffolding" for symbolic representations. Critically, it requires less cognitive sophistication to merely maintain and use symbolic representations provided by others (in the form of verbal description) than it does to generate the appropriate representations oneself. Three-year-olds succeed at the physical location task because they need only maintain a representation of a past physical situation, not a belief about a past situation. They succeed at the verbal-only mental location task because the experimenter provides the necessary symbolic encoding in verbal form and there is no direct perceptual experience generating conflicting representations. However, they fail at the standard theory-ofmind tasks because their rudimentary symbolic representations, even when verbally generated by the experimenter, are insufficient to override an experience-based interpretation of the true situation. We should also explain why 3-year-olds, and even younger children, can engage in elaborate pretend play (Leslie 1987). Although it involves symbolic representations or meta-representations that conflict with current perceptual experience (e. g., a block that stands for a car), the demands on the symbolic