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A video model was told to look broadly first, then narrow down, and it found subtle anomalies that flat classification missed

AspireAI community · arXiv (JiYuan Wang et al., NeurIPS 2026)
Video reward models that judge a clip in one pass tend to miss anomalies that are small on screen but obvious in time. Concentrate and Concentrate (CaC) scans coarsely before it looks closely: a global temporal scan anchors the suspicious window, fine-grained spatial grounding localises it inside that window, and a structured spatiotemporal chain-of-thought produces the verdict. To train it, the team built the first large-scale generated video anomaly dataset with per-frame bounding boxes, temporal windows and fine-grained attribution labels, then used a three-stage recipe of supervised fine-tuning and a two-turn GRPO pass with extra Temporal and Spatial IoU rewards for the localisation step. CaC gained 25.7% accuracy on fine-grained anomaly benchmarks, and used as a reward signal it reduced anomalies in generated video by 11.7% while improving overall video quality. The caveat is that the dataset is generated rather than collected, so the gains reflect the generator's own notion of an anomaly.
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One distance function matched sparse-autoencoder features across layers and compressed feature circuits into supernodes
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.
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