Validating the Online Circle Test (OL-CT): Cross-Format Equivalence, One-Week Reliability, and Depressive Symptom Correlates in Japanese Undergraduates

Background The Circle Test is a drawing-based task for assessing time perspective, and its indices have been linked to psychological well-being, including depression symptoms. However, conventional paper-and-pencil administration requires substantial human resources for scoring and quantification, limiting its scalability for large or remote surveys to be conducted. We developed an online web-based circle test with automated scoring and evaluated its validity and reliability. Methods Thirty-six Japanese undergraduates completed both the Online Circle Test (OL-CT) and paper-and-pencil Circle Test (PP-CT) in a counterbalanced crossover design (Visit 1) and repeated the OL-CT after 7–9 days either in the laboratory or at home (Visit 2). Continuous indices included log-transformed absolute and proportional areas, and categorical indices included temporal dominance and temporal relatedness. Validity analyses evaluated (a) cross-format equivalence between PP-CT and OL-CT and (b) clinical validity through associations with depressive symptoms measured using the Japanese version of the Patient Health Questionnaire-9 (J-PHQ-9). Reliability analyses evaluated (a) the one-week test-retest reliability of the OL-CT and (b) the contextual stability across laboratory versus home administration. Results Cross-format equivalence was moderate for log-transformed absolute areas (ICC = .73-.77) but excellent for proportional areas (ICC = .89-.90). The categorical agreement was high (88.9%), with no systematic category shift. For clinical validity, higher J-PHQ-9 scores were associated with a greater representational emphasis on the past, whereas future indices were not significant predictors in this non-clinical sample. One-week test-retest reliability was moderate-to-excellent for absolute areas (ICC = .69-.89) and excellent for proportional areas (ICC = .93-.95). Categorical stability was also high (temporal dominance: 91.7%, κ = .88; temporal relatedness: 86.0%, κ = .76). The OL-CT indices did not differ between the laboratory and home retesting contexts. Conclusion The OL-CT demonstrates strong validity and reliability as a scalable digital time-perspective assessment, with particularly robust proportional indices and stable categorical profiles across formats, time, and testing contexts.