Title : The absolute beginner. Right-and lefthand process-based measures in handwriting
Abstract:
Fine motor performance across ages is traditionally assessed through handwriting and drawing, focusing on both the final product and the kinematic aspects of the movement (Blank et al., 2019; Smits-Engelsman et al., 2001; van Drempt et al., 2011). In kinematic analysis, tablet-based dynamic parameters, such as the number of velocity inversions and movement fluency (e.g., speed, frequency), have revealed important characteristics of handwriting development and maturation, particularly in early writers (Rueckriegel et al., 2008). When it comes to product quality, it is often assessed through human judgment (Hamstra-Bletz, De Bie, & Den Brinker, 1987). A notable attempt to digitize this evaluation is the use of the Dynamic Time Warping (DTW) method to assess the consistency of letter formation (Di Brina et al., 2008). Building on these insights, handwriting, whether evaluated for quality or kinematics, is also significantly influenced by cognitive factors such as spelling and motor sequence learning, which shape kinematic performance and overall writing efficiency (e.g., Kandel et al., 2006; Fitjar et al., 2021; Meulenbroek & van Galen, 1989). In this study, we aimed to assess fine motor skills by analyzing computerized kinematic and quality variables, isolating the impact of cognitive factors. To achieve this, we compared the dominant hand (DH) and non-dominant hand (NDH) in a group of 26 adults (4 males, mean age 28.8, range: 22-35). The rationale was that the DH serves as an expert in fine motor movements (Annett, 1992), while the NDH represents a non-expert hand, although still operating with a memorized motor pattern. Participants performed three letter formation tasks (normal velocity, fast, and accurate) and a path tracing task on a digitized tablet, with kinematics and DTW variables recorded via CSWin software (Marquardt et al., 2021). Linear mixed model analyses compared the two hands considering each collected measure as dependent variables. Results showed significant kinematic differences between the DH and NDH, with the DH displaying faster, more fluent movements, though no differences in global letterform coherence were found. It confirms executional outperformance of the DH over the NDH noted in previous literature (Dexheimer et al., 2007; Heuer et al., 2007) moreover DH and NDH seem to show a common level of representation in motor programming (Grosskopf et al., 2006). These findings, compared with prior research (Di Brina et al., 2008), suggest that letterform consistency might be not a powerful indicator of fine motor skills, but a robust indicator of motor sequence learning.
