[Tool use of objects emerge continuously.]

The developmental origins of humans' ability to use objects flexibly as tools remains controversial. Although the dominant approach for conceptualizing tool use development focuses on a qualitative shift in cognition near the end of the first year, we suggest that perception-action theory offers important clues for how infants' earlier exploratory behaviors set the stage for the emergence of tool use. In particular, we consider how infants' attempts to relate objects and surfaces enables them to learn how objects function as extensions of the hand and provide opportunities for practicing the actions that will be recruited for tool use later in development. In this connection, we discuss behavioral and kinematic studies on object manipulation, which show that infants relate objects to surfaces in a discriminative manner and gain greater motor control of banging over the course of the first year. In conclusion, a perception-action perspective suggests that tool use emerges more continuously over developmental time than has traditionally been maintained.