Real-time Processes in the Development of Action Planning

We tested developmental changes in the moment-to-moment interplay among perceptual, neural, and motor components of action planning using video, motion-tracking, head-mounted eye tracking, and EEG. Preschoolers (N = 32) and adults (N = 22) grasped a hammer to pound a peg. When the handle pointed toward their non-dominant hand, younger children (“nonadaptive children”) used a habitual overhand grip that interfered with wielding the hammer, whereas adults and older children (“adaptive children”) used an adaptive underhand grip. Adaptive and nonadaptive children differed in: when and where they directed their gaze to obtain visual information; neural activation of the motor system before reaching; and straightness of their reach trajectories. Nonadaptive children immediately used a habitual overhand grip and then gathered visual information, leaving insufficient time to form a plan before acting. We suggest that development of action planning depends on a real-time “tug of war” between habits and information gathering and processing.