Recurrent retrofitting cuts VLM language params 23.3% while beating the unpruned baseline

HildeKuehne · x · 2026-10-31

An arXiv paper by Madhav Iyengar, Andreas Geiger and Hilde Kühne retrofits depth recurrence into pretrained vision-language models: prune layers from the language backbone and loop over a remaining subset, with a linear adapter fusing each block's output back into token representations. A three-stage recovery (language-only pretraining, vision-language projector alignment, visual instruction tuning) uses distillation from the original model in stages one and three. On TinyLLaVA-1.4B, with no new vision-language data, the retrofitted recurrent model stores 23.3% fewer language parameters yet outperforms the unpruned baseline trained on the same recovery data. Ablations: block-wise recurrence beats layer looping; the adapter matters; distillation helps; variable recurrence during training improves robustness to different inference-time iteration counts.

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