Handwriting Isochrony in Autistic and Non-Autistic Children

Handwriting difficulties are frequently reported in autistic children and may interfere with academic performance and daily activities. However, whether fundamental motor principles such as isochrony are preserved in autism remains largely unexplored.To address this question, fifty-five autistic and fifty-nine age-matched non-autistic children (6–12 years), all with intellectual functioning within the normal range, traced the letter “e” at five different sizes on a graphic tablet.Kinematic data were analyzed using the power law MT = T₀ × Aγ, where MT is movement time, A the amplitude of “e”, T0 the baseline time and γ the degree of isochrony. Participants whose data adequately fit the power law (R² > 0.49) were retained for further analysis.In total, 18 autistic and 34 non-autistic children were included. Frequentist and Bayesian analyses revealed no group differences in the degree of isochrony (γ ≈ 0.46 across conditions) or baseline time (T0 ≈ 1.45 s).These findings suggest that isochrony constitutes a fundamental motor invariant preserved in autism, and that handwriting difficulties are more likely to arise from higher-level visuomotor or fine motor control processes rather than from impairments in basic temporal motor planning.

Auteurs Bordeaux Neurocampus