A comparative analysis of automated methods for nonverbal synchrony quantification in psychological counseling

Nonverbal synchrony (NVS) has been investigated in relation to key psychotherapy and counseling process variables, such as therapeutic alliance and session quality, with empirical evidence suggesting a potential association. However, findings remain inconsistent, and the concordance between different automated methods of quantifying NVS is still understudied. This study contributes to the limited body of methodological research by comparing two principal NVS quantification approaches – the Ramseyer-Tschacher and Altmann methods – analyzing their relationship under both homogeneous (uniform) and heterogeneous parameter settings (method-specific). An analysis of 13 counseling sessions revealed strong positive correlations between most NVS measures under homogeneous settings (ρ = 0,17 to 0,92), particularly for overall synchrony strength and frequency. In contrast, under heterogeneous settings, while internal correlations within each method remained stable, cross-method correlations became weak or negative (ρ = –0,30 to 0,25). Notably, measures of synchrony strength within synchrony intervals showed distinct patterns of correlation relative to other NVS indicators, suggesting that they may reflect different aspects of synchronous behavior. These findings highlight the critical impact of parameter settings on NVS measurement and emphasize the need for greater methodological standardization in this field. Furthermore, the results indicate that different quantification methods may be sensitive to different temporal characteristics of synchrony, which has implications for both research and clinical applications. Additionally, these findings suggest that automated NVS quantification could potentially serve as an objective alternative to questionnaire-based assessments of counseling session quality, though substantial validation work addressing parameter sensitivity would be required before implementing such applications. This study contributes to the growing body of research on NVS by addressing key methodological considerations for future investigations.