KMAN Publication Inc. (KMANPUB) Journal of Adolescent and Youth Psychological Studies (JAYPS) 2981-2526 7 Serial Number 41 2026 01 10 Development of a Cognitive–Physical Dual-Task Intervention Package and Its Effectiveness on Evidence Rate (Evidence Accumulation Speed) in Adolescent Girls Development of a Cognitive–Physical Dual-Task Intervention Package and Its Effectiveness on Evidence Rate (Evidence Accumulation Speed) in Adolescent Girls 1 11 10.61838/kman.jayps.4762 EN Journal Article 2025 07 27 <table> <tbody> <tr> <td> <p><strong>Objective:</strong> The present study was conducted with the aim of developing a cognitive–physical dual-task intervention package and examining its effectiveness on the evidence rate (evidence accumulation speed) in adolescent girls.</p> <p><strong>Methods and Materials:</strong> This research employed a quasi-experimental design with pretest–posttest–follow-up and a control group. The statistical population consisted of low-active adolescent girls in Tehran in the 2024–25 academic year. Using convenience sampling, 50 participants were selected and randomly assigned to experimental and control groups (25 in each group). The experimental group received training based on the designed cognitive–physical dual-task package over eight weeks in twenty-four 20-minute sessions. The control group performed moderate-intensity aerobic exercises, starting from below-threshold intensity and progressing to moderately high intensity. To assess cognitive changes, the Wisconsin Card Sorting Test (WCST) was used, with “perseverative errors” and “total errors” serving as indices of cognitive flexibility and evidence accumulation speed. The process of developing the intervention package included designing training lesson plans, a teenager’s workbook, and evaluating content validity using CVR and CVI indices, which ranged from 0.8 to 1 and 0.9 to 1, respectively, confirming the satisfactory validity of the package. Data were analyzed using repeated measures ANOVA.</p> <p><strong>Findings:</strong> The results showed that the mean perseverative errors and total errors in the experimental group decreased significantly compared to the control group at posttest and follow-up (p &lt; 0.01). Effect size and eta squared also indicated a considerable impact of the cognitive–physical exercises on increasing the evidence accumulation rate.</p> <p><strong>Conclusion:</strong> The designed package significantly improved cognitive flexibility and decision-making processing speed in adolescent girls. These findings support the effectiveness of integrative mind–body approaches in enhancing fine-grained cognitive indices during adolescence.</p> </td> </tr> </tbody> </table> https://journals.kmanpub.com/index.php/jayps/article/download/4762/8615