The cognition and ergonomic design of a direct manipulation digital drawing pen for children

Presently, direct manipulation-based digital drawing developments have mostly focused on adult cognition. The adult design principles do not apply to children because their needs, skills, and expectations all differ. Thus, we conducting research and survey related to the field of children's digital drawing are essential. This study mainly recruited children aged 7–10 years as research participants. After investigations, we found that: (1) Children often use brush selection, brush stroke thickness changes, color changes, color fill functions, and eraser functions. (2) The sizes of the digital pen for children (7–10 years old): Length 120 mm, diameter 8 mm, hexagonal cross-section. (3) From the tilt angles of the pen and the multiple regression analysis of stroke thickness, we obtained the following formula: tilt angle = thickness × 5.584 + 3.223. (4) The buttons on the digital pen: When used the two buttons, the spacing 4 mm, and when used more than 3 buttons (contains 3 buttons), the spacing 2.5 mm. Fourteen participants were randomly asked to use “intuitively operated stylus pens (pressing the button, sliding the pen, rotating the pen, and tilting the pen)” and “conventional clicking interfaces” in turn. We collected user data and the error rate during the operational performance and provided subjective evaluations, specifically regarding the participant's drawing function (stroke thickness) operation when “different options were provided for drawing functions.” The results of the experimental showed that the direct movements for drawing pictures using the digital drawing pen, button-pressing, sliding, and rotating showed superior intuitiveness compared to tilting for children. When the number of selections increases, not suitable for used to rotating and tilting. According to the subjective evaluation conducted by the participants, direct manipulation can increase children's enjoyment of drawing.