Unleashing the power of untuned large language models in recommender systems: a thorough investigation of current approaches, challenges, and future research directions
摘要
The emergence of large language models (LLMs) has fundamentally redefined the landscape of artificial intelligence, offering remarkable capabilities in natural language understanding, generation, and reasoning. In the domain of recommender systems (RS), these advancements present new opportunities for addressing enduring challenges such as the cold-start problem, data sparsity, domain adaptation, explainability, and user engagement. Yet the substantial cost, complexity, and resource demands of fine-tuning these models limit their widespread adoption. This review investigates an alternative paradigm-leveraging untuned LLMs for RS—where general-purpose language models operate without task-specific parameter updates, relying on prompt engineering, zero-shot learning, and in-context learning. By analyzing 41 state-of-the-art articles, we find that untuned LLMs can adeptly generate context-aware, personalized, and human-aligned recommendations at reduced computational overhead, exhibiting notable performance in synthetic user–item interactions, semantic preference inference, zero-shot retrieval, and cross-modality reasoning for text, images, videos, and graph-based data. Our synthesis highlights successful integrations with graph neural networks (GNNs), vision language models (VLMs), and retrieval-augmented frameworks that improve recommendation accuracy, novelty, and user satisfaction, while uncovering key limitations such as hallucination, evaluation inconsistencies, fairness gaps, and inefficiencies in large-scale deployment. To address these concerns, we propose a structured set of future research directions, including scalable model compression (e.g., quantization, LoRA), fairness-aware and human-aligned evaluation metrics, synthetic data quality assurance, and domain adaptation strategies applicable to e-commerce, education, health care, and entertainment. We position untuned LLMs as a transformative force for next-generation RS, offering a scalable, explainable, and adaptive foundation for developing intelligent, user-centric systems in diverse real-world scenarios.