The developmental origins of naïve psychology in infancy.

Adv Child Dev Behav. 2009;37:55-104

Authors: Poulin-Dubois D, Brooker I, Chow V

Abstract

Research interest in children's understanding of the mind goes back as far as Piaget's claim that children are cognitively egocentric (Flavell, 2000). Many years later, research on the understanding of the mind was revived in a paper that sought evidence for a theory of mind, not for children but for chimpanzees (Premack & Woodruff, 1978). The researchers claimed that chimpanzees' ability to predict what a human actor will do to achieve certain goals implies that the animal attributes mental states to the actor. This seminal paper generated a flurry of studies on theory of mind in nonhuman primates. A review of this research based on several different experimental paradigms concluded that chimpanzees understand others in terms of a perception-goal psychology (i.e., they can perceive what the other's goal is but not understand the mental states associated with the goal), as opposed to a full-fledged, human-like belief-desire psychology (Call & Tomasello, 2008). Around the same time, research on children's understanding of the mind was revived in a landmark paper by Wimmer and Perner (1983) and by other developmentalists (Bretherton, McNew, & Beegly-Smith. 1981). In line with the research on nonhuman primates, part of the progress that has been made in recent years is a recognition that theory of mind knowledge is acquired in an extended series of developmental milestones and that this development is based on a rich set of socio-cognitive abilities that develop in infancy (Wellman, 2002). The evidence outlined in the sections of this chapter suggests that infants possess a nascent understanding of mental states that older children use in explaining and predicting human behavior. Researchers have learned a great deal about the developmental origins of naive psychology in infancy. Nevertheless, the depth of infants' understanding of human behavior is still a controversial issue. For example, a popular paradigm in naive psychology is violation of expectancy. In false-belief tasks, infants look longer at a scene.in which a protagonist searches for an object in a location she does not know than at a scene in which the protagonist searches for an object in a location where she has previously seen the object disappear. The fact that no active behavioral response is required makes many researchers doubt that an infants' looking pattern reflects a deep level of understanding. Looking pattern may simply reflect the infants' detection that something in the scene is novel (e.g., protagonist looks at a location different than the one infants last saw her look at). Indeed this interpretation may account for the conflicting results in recent studies (e.g., Poulin-Dubois et al., 2007; Onishi & Baillargeon, 2005; Surian et al., 2007). Poulin-Dubois et al. (2007) recently reported that the ability to distinguish between knowledge and ignorance (true belief) is absent at 14 months of age and still fragile at 18 months in a violation-of-expectancy task depicting videotaped human actors. In contrast, false-belief attribution to a computer animated caterpillar has been reported in 13-month-old infants (Surian et al., 2007). Given that infants have had more experience with humans looking at objects than with a caterpillar's looking behavior, the current evidence for an implicit understanding of advanced mental states such as false belief should be interpreted with caution. As is the case for nonhuman primate research, infants' mind-reading success might be accounted for by a simple behavior-reading explanation