Evaluation of handwriting task difficulty based on detrended fluctuation analysis

The control of voluntary movements is a dual structure consisting of cognitive and physical controls; cognitive control involves attentional resources, unlike physical control. Various voluntary movements can be performed by combining cognitive and physical controls. Body movements depending on attentional resources are performed using cognitive control; these movements fluctuate with white noise and their fluctuations gradually become the one-over-f fluctuation as the dependence on the attentional resources decreases. The handwriting process of characters is a voluntary movement. This study focused on the relationship between the repetitive handwriting process and the attentional resources allocated to it. The attention resources allocated to the handwriting process depend on the difficulty of the handwriting task. Moreover, the difficulty of a handwriting task is determined by the complexity of the shape of the handwritten characters, and the stroke counts is one indicator of this. Therefore, we focused on five Chinese kanji characters with different stroke counts. We investigated fluctuations in the temporal and spatial handwriting elements (twelve handwriting elements in all) defined within the handwriting process of each Chinese kanji character. The detrended fluctuation analysis was applied to the fluctuation analysis of the handwriting elements. In this paper, we discussed the relationship between the handwriting task difficulties and handwriting elements using local scaling indices based on the detrended fluctuation analysis.