Personalized Parameter-Efficient Fine-Tuning of Foundation Models for Multimodal Recommendation

TL;DR

This paper introduces PerPEFT, a personalized parameter-efficient fine-tuning method for multimodal recommendation systems that improves performance by conditioning item embeddings on user interests while maintaining lightweight adaptation.

Contribution

It proposes a novel user-group based PEFT approach that enhances multimodal recommender models with personalization, compatible with any PEFT method, and demonstrates significant performance gains.

Findings

PerPEFT outperforms baseline models by up to 15.3% in NDCG@20.

The method provides consistent improvements across various PEFT variants.

PerPEFT adds only 1.3% of the foundation model's parameters, maintaining efficiency.

Abstract

In recent years, substantial research has integrated multimodal item metadata into recommender systems, often by using pre-trained multimodal foundation models to encode such data. Since these models are not originally trained for recommendation tasks, recent works efficiently adapt them via parameter-efficient fine-tuning (PEFT). However, even with PEFT, item embeddings from multimodal foundation models remain user-blind: item embeddings are not conditioned on user interests, despite the fact that users with diverse interests attend to different item aspects. To address this limitation, we propose PerPEFT, a personalized PEFT strategy for multimodal recommendation. Specifically, PerPEFT groups users by interest and assigns a distinct PEFT module to each group, enabling each module to capture the fine-grained item aspects most predictive of that group`s purchase decisions. We further introduce a specialized training technique that strengthens this user-group conditioning. Notably, PerPEFT is PEFT-agnostic and can be paired with any PEFT method applicable to multimodal foundation models. Through extensive experiments, we show that (1) PerPEFT outperforms the strongest baseline by up to 15.3% (NDCG@20) and (2) delivers consistent gains across diverse PEFT variants. It is noteworthy that, even with personalization, PEFT remains lightweight, adding only 1.3% of the parameter count of the foundation model. We provide our code and datasets at https://github.com/kswoo97/PerPEFT.