Whose delay matters? Reply latency, emotional occurrence, and onset timing in group-based messaging among Japanese adolescents and emerging adults

Reply latency can carry interpersonal meaning beyond elapsed time, yet its emotional implications in group messaging remain less understood than in dyadic communication. This study examined anticipated emotional occurrence, conditional-on-occurrence onset timing, and their integrated occurrence-by-time patterns in group-based messaging among Japanese high school and university students ( N = 590). A vignette-based mixed factorial survey design compared separate waiting- and delaying-role survey samples, with target status, relationship type (best friend vs. romantic interest), and read status varied within participants. Emotional occurrence was analyzed using participant-cluster-robust logistic regression, conditional onset using partial proportional-odds models with participant-jackknife inference, and the two components were integrated into standardized occurrence-by-time probabilities. Waiting was associated with higher occurrence probabilities of anxiety, sadness, and anger, whereas delaying was associated with higher guilt occurrence. Among occurrence-positive judgments, onset tended to be anticipated earlier under delaying. However, the integrated analyses qualified this pattern: for anxiety, sadness, and anger, delaying-role probabilities were only slightly higher at early thresholds, whereas waiting-role probabilities became substantially higher at later thresholds. Guilt showed a distinct pattern, with integrated probabilities remaining higher under delaying throughout. Relational differentiation was clearest for anxiety and sadness in occurrence and appeared more selectively in conditional timing. These findings show that earlier conditional onset does not necessarily correspond to higher integrated occurrence-by-time probabilities across all judgments, underscoring why emotional occurrence and conditional timing should be considered jointly when interpreting reply latency as a socially structured chronemic cue in multi-person communication.