Data Sources and Citation Metrics
The 5th edition of the Research.com Best Psychology Scientists in Japan Ranking was developed using comprehensive bibliometric data sourced primarily from OpenAlex and CrossRef, complemented by a range of additional reputable data repositories. The citation-based metrics utilized to formulate the ranking were derived from data collected on 2026-01-12. A key metric employed is the D-index (Discipline H-index), which assesses a researcher’s impact specifically within the discipline of Psychology by considering only those publications and citations related to the examined field. This focused approach ensures that the ranking accurately reflects a scientist's scholarly contributions in Psychology rather than generalized academic output.
Scope of Research and Qualification Criteria
The ranking process involved the examination of 279,971 scientist profiles aggregated from multiple bibliometric data sources across all scientific disciplines. Within the specific domain of Psychology, 38 leading scientists were identified for consideration. To qualify for inclusion in the Psychology ranking, each scientist was required to have a D-index of at least 30, with the majority of their tier publications concentrated within the field of Psychology. In addition, notable awards and recognized achievements in Psychology were considered as supplementary factors in the evaluation.
The threshold for the D-index is adjusted incrementally—by steps of 10—based on the estimated total number of scholars in each discipline. This scalable thresholding is designed to ensure that the top 1% of leading experts are represented in the ranking. Furthermore, to validate disciplinary focus, a proximity criterion was applied whereby the difference between a scientist’s general H-index and their Psychology-specific D-index does not exceed 30%, safeguarding that listed researchers maintain a strong specialization in the discipline.
Additional Verification and Methodological Rigor
Recognizing that raw bibliometric data alone cannot fully capture a scholar’s impact, all scientist profiles included in the ranking underwent manual verification. This process involved cross-correlating publication records with a broad spectrum of trusted academic sources to confirm accuracy and relevance. Although not directly influencing the ranking position, the number of papers published in prestigious journals and conference proceedings is regarded as an important secondary indicator of a scientist’s contribution to Psychology research.
The ranking’s primary positioning is grounded in the rigorously compiled D-index derived from the most authoritative bibliometric databases available, namely OpenAlex and CrossRef. These databases are widely recognized within the research community for their comprehensive, up-to-date coverage of scholarly publications and citations.
For a detailed exposition of the ranking methodology, readers are invited to visit our methodology page.
Research.com’s Mission and Commitment
Research.com is dedicated to fostering a deeper understanding of research excellence by providing transparent, reliable, and comprehensive rankings of scientists worldwide. Our mission is to motivate researchers, companies, and policymakers globally to actively examine the trajectories of leading experts, thereby facilitating informed decision-making. Equally, we seek to offer the entire scientific community an accessible platform to identify and engage with top scholars in specific research areas, across countries and within individual academic institutions. Through meticulous data collection, verification, and presentation, we strive to uphold the highest standards of credibility and precision in all our scholarly rankings.
