IAA: Inner-Adaptor Architecture Empowers Frozen Large Language Model with Multimodal Capabilities
Bin Wang, Chunyu Xie, Dawei Leng, Yuhui Yin
TL;DR
The paper tackles the challenge of preserving NLP capabilities while equipping frozen large language models with robust multimodal understanding. It introduces the Inner-Adaptor Architecture (IAA), which inserts adaptable multimodal layers inside a frozen LLM and adds a dedicated embedding layer and LM head for multimodal inputs, enabling effective image-text interaction without fine-tuning the LLM. Through a carefully designed two-stage pre-training, instruction fine-tuning, and grounding fine-tuning regimen, IAA achieves state-of-the-art or competitive results on general multimodal benchmarks and visual grounding with substantially smaller data requirements, while maintaining strong text-only NLP performance. The deployment-friendly design supports dual workflows (multimodal and text-only) and shows improved memory efficiency, suggesting practical applicability and potential extension to additional modalities in future work.
Abstract
In the field of multimodal large language models (MLLMs), common methods typically involve unfreezing the language model during training to foster profound visual understanding. However, the fine-tuning of such models with vision-language data often leads to a diminution of their natural language processing (NLP) capabilities. To avoid this performance degradation, a straightforward solution is to freeze the language model while developing multimodal competencies. Unfortunately, previous works have not attained satisfactory outcomes. Building on the strategy of freezing the language model, we conduct thorough structural exploration and introduce the Inner-Adaptor Architecture (IAA). Specifically, the architecture incorporates multiple multimodal adaptors at varying depths within the large language model to facilitate direct interaction with the inherently text-oriented transformer layers, thereby enabling the frozen language model to acquire multimodal capabilities. Unlike previous approaches of freezing language models that require large-scale aligned data, our proposed architecture is able to achieve superior performance on small-scale datasets. We conduct extensive experiments to improve the general multimodal capabilities and visual grounding abilities of the MLLM. Our approach remarkably outperforms previous state-of-the-art methods across various vision-language benchmarks without sacrificing performance on NLP tasks. Code and models are available at https://github.com/360CVGroup/Inner-Adaptor-Architecture.
