The road from from banging a block to drawing circles and fluent handwriting
What is the connection between banging a block on a table top and fluent handwriting?
The fluent production of a series of letters involves pre-planned rapid finger actions that are produced without visually guided online error correction. Each letter is formed by one or more strokes (sub-movements) each with a single acceleration-deceleration velocity profile.
The child’s ability to produce these well controlled rapidly repeated movements is built on a lifetime’s worth of experience starting from birth!
Infant shaking and banging actions
Infants engage in repeated bouts of repetitive movements from the first weeks of life. Early repetitive movements include kicking and batting at objects with the hands.
Repetitive movements of the hands while holding an object are particularly prominent in the months after the infant has learned to sit independently and include shaking rattles, and banging objects either on a surface or together.
These early shaking movements are linked to the emeragence babbling.
Early scribbling is another rapidly repeated action.
Forming action plans
These early repetitive actions provide the infant with multiple opportunities for developing internal models of arm actions. A model of the planned action is mapped onto the feedback from the proprioceptoras joints, muscles and skin as well as to the outcome of the action.
Action plan --> internal feedback (proprioception) + external feedback (consequences of action monitored by vision sound).
These repetitive actions are too fast to be visually guided – error correction cannot happen online.
Infant reach, grasp and manipulation
At the same time infants also starts to engage in slower more controlled actions as they practise posting objects, fitting them together and taking them apart. These actions are slower and have a defined outcome will often involve repeated exploratory attempts to get the action right. This class of actions requires careful attention to what the hand is doing and will sometimes involve online visual correction.
What about block banging?
Research has shown that the trajectory of the hand when reaching becomes straighter with practice and new research shows that even block banging gets more efficient with practice! Recent research by Kahrs et al looked at the changes in banging movements of infants between the ages of 7 and 12 months.
The infant was observed while sitting on the parent’s lap facing a table and banging a block on the table surface.
Such banging actions are rapidly repeated and build on the earlier experience with repeated shaking actions. In contrast to shaking actions however, there is a externally defined endpoint for the movement and the hand and block need to be carefully posotioned so as to make effective contact with the horizontal surface.
The results of this research showed that with increasing age and thus experience the infants’s banging actions improved in effectiveness and efficiency:
- The trajectory of the movement became straighter. The angle of contact between the block and table surface became smaller
- The velocitiy profile of the movements showed a single movement with a single acceleration and deceleration profile. (This in contrast to reaching movements with show several sub-movements and several velocity peaks, with online correction of the movement trajectory.)
- This increased direct downward movement of the hand was associated with increased ability to bring the block down flat against the surface of the table.
Kahrs, B. A., Jung, W. P., & Lockman, J. J. (2012). What is the role of infant banging in the development of tool use? Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale, 218(2), 315–20. doi:10.1007/s00221-012-3062-3
von Hofsten C (1979) Development of visually directed reaching: the approach phase. J Hum Mov Stud 5:160–178