Development of adaptive tool-use in early childhood: sensorimotor, social, and conceptual factors.

Tool-use is specialized in humans, and juvenile humans show much more prolific and prodigious tool-use than other juvenile primates. Nonhuman primates possess many of the basic motor and behavioral capacities needed for manual tool-use: perceptual-motor specialization, sociocultural practices and interactions, and abstract conceptualization of kinds of functions, both real and imagined. These traits jointly contribute to the human specialization for tool-using. In particular, from 2 to 5 years of age children develop: (i) more refined motor routines for interacting with a variety of objects, (ii) a deeper understanding and awareness of the cultural context of object-use practices, and (iii) a cognitive facility to represent potential dynamic human-object interactions. The last trait, which has received little attention in recent years, is defined as the ability to form abstract (i.e., generalizable to novel contexts) representations of kinds of functions, even with relatively little training or instruction. This trait might depend not only on extensive tool-using experience but also on developing cognitive abilities, including a variety of cognitive flexibility: specifically, imagistic memory for event sequences incorporating causal inferences about mechanical effects. Final speculations point to a possible network of neural systems that might contribute to the cognitive capacity that includes sensorimotor, sensory integration, and prefrontal cortical resources and interconnections.