Analyzing Influential Factors in Review-Based Restaurant Recommender Systems: The Role of Review Length, Aspect, and Emotion

Review text in recommender systems provides rich insights into user preferences and experiences that cannot be fully captured by numerical ratings alone. While recent studies have increasingly leveraged review text to enhance recommendation accuracy, most have primarily focused on improving model performance, with limited attention to quantitatively examining how specific textual elements influence rating prediction. To address this gap, this study empirically investigates the impact of review text characteristics on prediction performance in review-based recommender systems. Specifically, we employ the Unstructured Context-Aware Model (UCAM), where contextual information is replaced with review text embedded using a pre-trained BERT model. Three key textual factors are examined: review length, aspect, and emotion type. Review length is divided into quartiles, and results show that removing shorter reviews significantly degrades performance, indicating their critical role. For analysis, reviews are categorized into food, service, price, atmosphere, and location, with service and food contributing most to performance improvements, while location shows relatively low influence. Emotion types are classified based on Plutchik’s framework, revealing that removing joy, trust, and anticipation reduces performance, whereas excluding sadness slightly improves it. Overall, this study highlights the differential importance of textual features and demonstrates their potential for enhancing recommender system design.