Assessment of children's writing features: A pilot method study of pen-grip kinetics and writing surface pressure

The writing process is a complex task involving dexterous manipulation of the writing instrument by the hand digits and biomechanical ergonomic factors that contribute to handwriting efficiency and productivity. We describe a pilot study using an instrumented writing apparatus - a sensor (pen) and a digitized writing surface (tablet) - to measure the pen-grip kinetics (digit forces) and the pen pressure applied to the tablet during a writing task. Eight elementary school students with no handwriting difficulties copied a short story. The mean digit forces on the pen were compared with the mean pen pressure on the tablet at five interval points. Results revealed that the digit forces on the pen were significantly stronger than the pen pressure on the tablet. Results also showed significantly less digit-force variability throughout the writing task than the pen-pressure variability on the writing surface, which significantly lessened toward the end of the writing task. Information on these properties can broaden understanding of the elements that influence nonproficient handwriting in children with dysgraphia. Results also indicate the possible efficacy of a therapeutic tool for handwriting assessment and intervention using objective measurements during writing, warranting future studies with children with and without dysgraphia.