Profiling handwriting process deviations in children with dysgraphia
Profiling Handwriting-Process Deviations in Developmental Dysgraphia: An Open, Normatively-Referenced Instrument
Human-Computer Interaction
Summary
Children with developmental dysgraphia struggle with handwriting, but existing tools mostly analyze the final written product rather than the handwriting process. The authors created an open tool that measures and compares how children write sentences on a tablet, by looking at 136 detailed features grouped into 12 categories. They tested their tool with over 250 children, showing it can reliably highlight differences in handwriting movements and timing without labeling children as dysgraphic. The tool and data are freely available for others to use and build upon.
What this means in practice
- •For occupational therapists: Use detailed, norm-referenced handwriting process profiles to tailor interventions for children with handwriting difficulties.
- •For digital pen developers: Integrate an open, validated instrument for quantifying handwriting deviations to enhance diagnostic features in writing-assist devices.$Commercial implications: Enables pen manufacturers to offer diagnostic tools for handwriting disorders to therapists and schools, improving product value.
Authors
Jihyun Mun, Mounîm A. El-Yacoubi
Abstract
Online handwriting captured on digitizing tablets yields hundreds of kinematic, temporal, spatial, and dynamic features. These features are rarely organized into interpretable, reusable constructs, and, although standardized tests norm the handwritten product, no openly available instrument places a child's handwriting process relative to a verified-typical reference. We introduce and validate an open measurement instrument for profiling handwriting-process deviations in children with developmental dysgraphia from sentence-level online handwriting. The instrument comprises (i)~a literature-only vocabulary, fixed before any cohort analysis, organizing 136 online-handwriting features into 12 handwriting-process domains, and (ii)~an age- and sex-adjusted normative reference framework, fit on verified-typical children only, that turns those features into a 12-axis deviation profile with per-child bootstrap uncertainty. We establish its measurement properties on the DiaGraMo cohort (N=257 Czech children aged 8--12; 110 verified-typical, 147 with dysgraphia): the vocabulary is structurally coherent, and the reference is calibrated, parsimonious, and leakage-free. On the same cohort, five of twelve domains separate the groups at BH~$q<.05$ (Cliff's~$δ$ +0.19 to +0.51), on spatial, temporal, and pen-orientation processes, and 96.5\% of participant~$\times$~domain scores have a bootstrap CI narrower than one z-unit. No classifier is trained: the instrument reports uncertainty-aware deviation scores rather than a diagnostic label, and its outlier rate is not a diagnostic rate. The vocabulary, the analysis code, and an open reference implementation that scores new participants are all openly released, giving handwriting and dysgraphia researchers a reusable, validated instrument for situating individual children against a normative reference.