Document Type : Original Article
Authors
1
Ph.D. Candidate in Cognitive Psychology, Department of Psychology, Faculty of Education and Psychology, Ferdowsi University of Mashhad, Mashhad, Iran
2
Associate Professor, Department of Psychology, Faculty of Education and Psychology, Ferdowsi University of Mashhad, Mashhad, Iran.
3
Professor, Department of Psychology, Faculty of Education and Psychology, Ferdowsi University of Mashhad, Mashhad, Iran.
4
Professor, Department of Rehabilitation, Jönköping University, Jönköping, Sweden
Abstract
Introduction
Developmental Coordination Disorder (DCD) is a prevalent neurodevelopmental disorder of childhood, with prevalence estimates of 5–6% (Bieber et al., 2023). Beyond impairments in learning and executing motor skills (Cardillo et al., 2025), DCD can be associated with deficits in executive functions, attention, cognitive inhibition, and information processing (Altman et al., 2025). Inhibitory control is defined as the ability to suppress a dominant, automatic, or inappropriate response or cognitive process. It is considered a fundamental component of executive functions (Ikeda et al., 2014). Despite numerous reports indicating inhibitory deficits in children with DCD (Joshi et al., 2022), findings from previous studies are not entirely consistent (Koch et al., 2018). One potential explanation for this discrepancy may be the overreliance on a single metric, such as reaction time or error count, while disregarding the speed–accuracy trade-off. The Inverse Efficiency Score (IES) enables concurrent evaluation of speed and accuracy by integrating reaction time and error rates (Baek et al., 2023; Statsenko et al., 2020). Furthermore, Receiver Operating Characteristic (ROC) curve analysis and the Area Under the Curve (AUC) can determine the discriminative power of performance metrics in distinguishing children with DCD from typically developing children (Çorbacıoğlu & Aksel, 2023). To date, no study has simultaneously used IES and ROC analysis to examine interference control in children with DCD. The present study had two objectives: first, to compare the performance of children with DCD and typically developing children on the Stroop-like big–small task, and second, to evaluate the discriminative power of reaction time, error count, and IES using ROC analysis.
Method
A total of 1,693 children aged 7–10 years in Babolsar participated in a three-stage screening process. The screening incorporated the Developmental Coordination Disorder Questionnaire-07 (DCD07), the Movement Assessment Battery for Children–Second Edition (MABC-2), DSM-5 criteria, and the Strengths and Difficulties Questionnaire. Children exhibiting indications of ADHD or ASD were excluded, as were two children with DCD who demonstrated a response accuracy of less than 25%. The final sample comprised 22 right-handed children diagnosed with DCD (11 girls and 11 boys; mean age 8.76 years) and 26 right-handed children categorized as having typical development (10 girls and 16 boys; mean age 8.69 years). Participants performed the Stroop-like big–small task under congruent and incongruent conditions (each comprising 40 stimuli), and their reaction times and response accuracy were recorded. The IES index and the IES interference cost were calculated. Group comparisons were conducted using independent t-tests, or Welch's t-tests in cases of unequal variances. Furthermore, to assess the discriminative capability of the indices, an ROC analysis was conducted, incorporating the AUC, determination of the optimal cut-off point, sensitivity, specificity, and the Youden index.
Findings
In comparison with typically developing children, children with DCD demonstrated prolonged reaction times and a higher number of errors in the congruent condition. These differences were statistically significant (p < 0.01 and p < 0.05, respectively). In the incongruent condition, the DCD group also exhibited prolonged reaction times (p < 0.01) and committed a greater number of errors (p < 0.001). The IES values in both congruent and incongruent conditions were significantly higher in the DCD group than in the typically developing group (both p < 0.001). Additionally, the IES interference cost was higher in children with DCD (p < 0.01). ROC analysis revealed that IES in the incongruent condition—with an AUC of 0.904 (95% CI: 0.817–0.991)—had the greatest discriminative power among the indices examined. The optimal cutoff point was determined to be 1.123, yielding a sensitivity of 95.5%, a specificity of 76.9%, and a Youden index of 0.724. Furthermore, several indices exhibited discriminative power exceeding 0.7: congruent reaction time (AUC = 0.766), congruent error count (AUC = 0.719), congruent IES (AUC = 0.804), incongruent reaction time (AUC = 0.802), incongruent error count (AUC = 0.879), and IES interference cost (AUC = 0.799). Among the indices with an AUC greater than 0.8, incongruent IES, incongruent error count, congruent IES, and incongruent reaction time demonstrated favorable performance.
Discussion
The findings indicated that children with DCD exhibited prolonged response times and an increased number of errors in both congruent and incongruent conditions, aligning with previous evidence regarding deficits in inhibition and executive attention in this population (He et al., 2018; Wilson et al., 2020). This pattern may be indicative of reduced inhibitory efficiency, slower processing, or difficulty suppressing dominant responses. However, determining the independent contribution of these processes requires further research. Furthermore, the inverse efficiency score was higher in the DCD group, particularly in the incongruent condition. This finding suggests that the integration of speed and accuracy provides a more nuanced assessment of performance disparities between the two groups. This finding aligns with evidence regarding reduced neural efficiency and the recruitment of compensatory resources in DCD (Subara-Zukic et al., 2022), as well as increased mental effort required to manage interference (Grund et al., 2024). ROC analysis revealed that the IES in the incongruent condition offered the best discriminative power among the examined indices, consistent with evidence regarding the utility of performance-based metrics in distinguishing clinical groups (Çorbacıoğlu & Aksel, 2023). However, the limited sample size and uncertainty of the estimates preclude the use of IES as a substitute for standard DCD diagnostic tools. Its cutoff point requires validation in larger, independent samples. In general, children with DCD exhibited poorer performance in terms of speed, accuracy, and cognitive inhibitory processing efficiency. Due to the restricted sample size, the modest number of trials, and the fixed presentation order (where congruent conditions precede incongruent ones), the findings should be generalized with caution. Future studies employing larger samples, balanced condition orders, a more diverse array of tasks, and neuroimaging methods could further investigate these findings and their underlying cognitive and neural mechanisms.
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