OF DISPOSITIONAL STATES BY 12-MONTH-OLDS

The ability to interpret the behavior of other individuals is essential for effective social functioning. Many investigators now believe that even young infants can recognize that agents act toward goals. Here we report three experiments suggesting that 12-month-old infants not only can recognize goal-related action, but also can interpret future actions of an actor on the basis of previously witnessed behavior in another context. The possibility that this inference is made through the attribution of mental states is discussed. The ability to interpret the behavior of other individuals is essential for social functioning. Without the ability to infer emotions, desires, and beliefs—for instance, that John is angry, Mary wants to leave, or Betty thinks that it is cold outside—it would be impossible to predict or understand the behavior of other people. Although the ability to reason about certain mental states such as beliefs and false beliefs might emerge between the ages of 3 and 5 years (Gopnik, 1993; Wellman, 1990; Wellman, Cross, & Watson, 2001), there is growing interest in infants’ reasoning about the behavior of others (e.g., Gergely, Nadasdy, Csibra, & Biro, 1995; Meltzoff, 1995; Woodward, 1998). Recent studies have shown that infants do have some understanding of goal-related behavior. For example, in one study, 9and 12month-old infants were shown a computer-animated ball repeatedly jumping over a barrier to reach another object. When subsequently shown a modified display with the barrier removed, the infants expected the ball to move straight to the object to satisfy its goal, rather than repeat the jumping behavior (Csibra, Gergely, Biro, Koos, & Brockbank, 1999; Gergely et al., 1995). Twelve-month-old infants can also recognize the underlying positive or negative “valence” of an action; the helping actions of one computer-animated actor toward another are seen as similar to caressing actions, whereas a hindering act is seen as similar to a hitting act (Premack & Premack, 1997a). However, many researchers have noted that such sensitivity to goal-related behavior need not imply that infants are attributing mental states to the actors (Gergely et al., 1995; Premack & Premack, 1997b; Woodward, 1998). Identifying a goal state that an actor tends to act toward does not require understanding how the actor mentally construes the situation (e.g., that the actor wants to reach the goal). For example, in the aforementioned studies, infants may have identified the specific, physical goal of an actor in a scene—that is, recognized simply that there was a tendency or disposition for the actor to act toward a given physical state. In the present studies, we sought to elaborate upon the type of attributions infants make when viewing goal-oriented behavior. Previous studies (e.g., Gergely et al., 1995; Woodward, 1998) have shown that after witnessing an actor engage in a specific goal behavior (e.g., approaching an object), infants recognize that the same goal behavior will occur in a subsequent situation with an altered spatial arrangement (e.g., the goal object has moved or an obstacle has been removed). However, what will infants attribute if the second situation is a completely different context from, yet is socially related to, the first? That is, will infants interpret an actor’s new behavior in this new situation on the basis of the history of that actor’s behavior in a different situation? Such a pattern of results would indicate that the infant’s ability to recognize an agent’s dispositions is more complex than previously shown. Furthermore, such a sophisticated ability might indicate that infants are actually attributing to the actor a mental-state mediator underlying the new behavior. The present experiments tested infants using movies consisting of animated geometric figures, a type of stimulus commonly used in the study of psychological reasoning in infants (Gergely et al., 1995; Wagner & Carey, 2002) and adults (Heider & Simmel, 1944; Thayer & Schiff, 1969). In Experiments 1 and 2, 5and 12-month-old infants were habituated to computer-animated movies depicting two objects (a square and a triangle), one engaging in helping behavior and one engaging in hindering behavior toward a third object (a ball) that attempted to climb a hill. The infants were then shown two new test movies in which all three objects were present in a new context in which the original goal state did not apply (no hill was present). In one test movie, the ball approached and settled next to its helper, and in the other movie, the ball approached and settled next to its hinderer. Pilot testing demonstrated that adults tended to see the ball as “liking” or “preferring” the helper object, because the ball completed its goal in concert with the actions of the helper in the habituation movies. Because of this interpretation, they differentiated between the test movies: When asked to choose between two interpretations, 9 of 10 adults reported that the test movie in which the helper object was approached was a coherent continuation of the previous habituation movies, whereas the test movie in which the hindering object was approached was not. We predicted that if infants interpreted the ball’s likely new disposition in the test-movie context on the basis of the previous actions in the habituation movies, they would also differentiate between the test movies, and looking times to the two movies would differ. Experiments 1 and 2 tested this hypothesis. Experiment 3 served to control for an alternative, associationist explanation for lookingtime patterns.