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The development of intentions: Understanding people and their actions
528 THE DEVELOPMENT
OF INTENTIONS: UNDERSTANDING AND THEIR ACTIONS
PEOPLE
Maria Legerstee, Department of Psychology, York University, 4700 Keele Street, Toronto, M3 J 1P3 The ability to act intentionally and to perceive intentions in others is a prerequisite to a conceptual understanding of people and allows for a clear differentiation between the social and the physical (Fry, 1989). The concept of a person implies an understanding that people have both social and physical attributes, such as intentions, emotions, size and shape, whereas objects have only physical attributes (Gelman & Spelke, 1981; Strawson, 1958). Because adults are aware ofthe different attributes of people and objects they interact differently with the two classes. They act on the physical properties of objects by manipulating them, but on the social attributes of people by communicating with them. Thus adults employ different and rational means/actions with people and objects in order to achieve a particular goal. In order to provide evidence that infants have a theory of how people act, one has to show that they too expect people to act rationally, rather than randomly, and according to social rules. Gergely et al (1995) propose that the principle of rationality of the infant’s theory of people assumes that whenever there are multiple available means that a person could perform to achieve a goal, they will choose the one that is most rational: that is, the action that will allow them to achieve their aim in the most optimal manner. If infants are able to predict the rational behavior of an agent from among the various behaviours that are possible to achieve a goal in a particular context, then one can assume that the infant has a theory of a person. To determine whether 6-month-old infants are able to generate rational predictions about people’s future behavior from observing their present actions, two groups of infants were randomly assigned to two experiments, and their gazes were recorded. In Experiment 1, infants were assigned to 2 conditions. In condition 1 (talking), an actor talked to something hidden behind a curtain saying “Hi, how are you, would you please move.” After the infants were habituated, the curtain was pulled away and the infants saw either a person move (rational event), or a broom move (fastened on an invisible trolley that was moved back and forth by a hidden assistant) (nonrational event). As predicted, infants looked longest at the non-rational event. In Condition 2 (acting), the above paradigm was repeated but now the actor performed actions (grabbing and moving arms in sweeping motions). Contrary to what was predicted, the infants looked longer at the rational event, where the actions were performed on the object than to the nonrational event, where the actions were performed on the person. In order to assess whether infants in condition 1 (talking) looked longer at the non-rational event because the broom moved independently, the above conditions were repeated in Experiment 2. Instead of having the actors continue their actions after the curtain had been opened, or the stimuli move, the actors stopped acting and the stimuli remained stationary. The results revealed that now, infants looked longer at the rational than the non-rational events in both conditions. The data shows that 1) Infants look longer at events that do not show violations of social behavior (rational events) than events that do (nonrational events). This is in contrast to studies that assess the infants understanding of physical objects, where infants look longer at events that violate physical principles (novelty effect) than those that do not, and 2) young infants focus on object specific desires of people (Wellman, 1990). They expect people to communicate to persons, but not to objects. This appreciation of social interactions seems to be a prerequisite to the older infants’ understanding that others have experiences about objects.
OF INTENTIONS: UNDERSTANDING AND THEIR ACTIONS
PEOPLE
Maria Legerstee, Department of Psychology, York University, 4700 Keele Street, Toronto, M3 J 1P3 The ability to act intentionally and to perceive intentions in others is a prerequisite to a conceptual understanding of people and allows for a clear differentiation between the social and the physical (Fry, 1989). The concept of a person implies an understanding that people have both social and physical attributes, such as intentions, emotions, size and shape, whereas objects have only physical attributes (Gelman & Spelke, 1981; Strawson, 1958). Because adults are aware ofthe different attributes of people and objects they interact differently with the two classes. They act on the physical properties of objects by manipulating them, but on the social attributes of people by communicating with them. Thus adults employ different and rational means/actions with people and objects in order to achieve a particular goal. In order to provide evidence that infants have a theory of how people act, one has to show that they too expect people to act rationally, rather than randomly, and according to social rules. Gergely et al (1995) propose that the principle of rationality of the infant’s theory of people assumes that whenever there are multiple available means that a person could perform to achieve a goal, they will choose the one that is most rational: that is, the action that will allow them to achieve their aim in the most optimal manner. If infants are able to predict the rational behavior of an agent from among the various behaviours that are possible to achieve a goal in a particular context, then one can assume that the infant has a theory of a person. To determine whether 6-month-old infants are able to generate rational predictions about people’s future behavior from observing their present actions, two groups of infants were randomly assigned to two experiments, and their gazes were recorded. In Experiment 1, infants were assigned to 2 conditions. In condition 1 (talking), an actor talked to something hidden behind a curtain saying “Hi, how are you, would you please move.” After the infants were habituated, the curtain was pulled away and the infants saw either a person move (rational event), or a broom move (fastened on an invisible trolley that was moved back and forth by a hidden assistant) (nonrational event). As predicted, infants looked longest at the non-rational event. In Condition 2 (acting), the above paradigm was repeated but now the actor performed actions (grabbing and moving arms in sweeping motions). Contrary to what was predicted, the infants looked longer at the rational event, where the actions were performed on the object than to the nonrational event, where the actions were performed on the person. In order to assess whether infants in condition 1 (talking) looked longer at the non-rational event because the broom moved independently, the above conditions were repeated in Experiment 2. Instead of having the actors continue their actions after the curtain had been opened, or the stimuli move, the actors stopped acting and the stimuli remained stationary. The results revealed that now, infants looked longer at the rational than the non-rational events in both conditions. The data shows that 1) Infants look longer at events that do not show violations of social behavior (rational events) than events that do (nonrational events). This is in contrast to studies that assess the infants understanding of physical objects, where infants look longer at events that violate physical principles (novelty effect) than those that do not, and 2) young infants focus on object specific desires of people (Wellman, 1990). They expect people to communicate to persons, but not to objects. This appreciation of social interactions seems to be a prerequisite to the older infants’ understanding that others have experiences about objects.