Developmental changes in the discrimination of dynamic human actions in infancy (original) (raw)

2011, Developmental Science

Recent evidence suggests adults selectively attend to features of action, such as how a hand contacts an object, and less to configural properties of action, such as spatial trajectory, when observing human actions. The current research investigated whether this bias develops in infancy. We utilized a habituation paradigm to assess 4-month-old and 10-month-old infants' discrimination of action based on featural, configural, and temporal sources of action information. Younger infants were able to discriminate changes to all three sources of information, but older infants were only able to reliably discriminate changes to featural information. These results highlight a previously unknown aspect of early action processing, and suggest that action perception may undergo a developmental process akin to perceptual narrowing. Effective management of one's daily affairs requires efficient processing of the actions of others. Processing human action is critical for understanding others' goals and intentions, which are in turn crucial for navigating social situations. Since human action is inherently complex and dynamic in nature, a powerful cognitive system that utilizes both top-down and bottom-up processes likely underlies action analysis (Baldwin, 2005). While adults can make use of top-down information to guide their action processing and goal inference, infants lack much of this information, and must rely more heavily on bottom-up processes to analyze others' behavior. Thus, investigating how infants process the actions of others provides a window into the development of early social cognition. One aspect of infant action perception that has yet to be directly examined is action discrimination-that is, infants' ability to perceive differences among actions. We use the term action to refer to the intentional movements of a human agent in the execution of a goal, including the initiation, unfolding, and completion of the movements. Characterized as such, there are numerous properties of action that a human agent can vary: the spatial trajectory of their actions, the speed of their actions, the particular limb used, the kind of grasp used, etc. Exploring action discrimination in infancy can reveal what properties of action infants attend to and encode during their observation of other's behavior. For instance, do infants readily discriminate between actions that vary according to a single property, such as speed? Are they better able to discriminate changes in certain properties over other properties? The goal of the current research was to investigate what properties of action infants attend to when observing actions, and whether their attention during action observation changes across development. What is known about infants' action discrimination comes from research exploring infants' goal understanding. Infants' ability to discriminate actions on the basis of goal information changes across development. Woodward (1998) tested whether infants understand that actions are directed toward particular goals. In her study, infants were habituated to an actor