Explain the task-dependent effects of two-stage prompting

Determine whether the first-pass media description provides a compact event-order scaffold that explains the observed gain in Cat1 minimal-span temporal grounding, and account for the mixed effects of two-stage prompting across the AVTrace task categories.

Background

The authors evaluate a two-stage prompting condition for Qwen3-Omni-30B in which the system first summarizes salient visual and audible events and their apparent order, then receives that summary together with the original media and task prompt. The intervention improves Cat1 performance but reduces performance on Cat2, Cat4, and Cat6, while producing no clear change on Cat5 and Cat7.

The authors offer the event-order scaffold as one possible explanation for the Cat1 improvement, but the heterogeneous effects across categories do not establish this mechanism. They explicitly leave the interpretation open for future investigation, making the relationship between intermediate temporal summaries and task-specific performance an unresolved problem.

References

One possible explanation for the Cat1 gain is that the first-pass description provides a compact event-order scaffold for the second-stage timestamp prediction; the mixed effects across categories leave this interpretation open for future investigation.

— AVTrace: Diagnosing Audio-Visual Temporal Reasoning in Omni Models  (2609.19991 - Zhang et al., 17 Sep 2026) in Section 5, subsection “Evidence removal, perturbation, and prompting”