Spatial Priming Outperforms Semantic Prompting: A Grid-Based Approach to Improving LLM Accuracy on Chart Data Extraction
Summary
This paper investigates methods for improving LLM accuracy in chart data extraction, finding that spatial priming via coordinate grids significantly outperforms semantic prompting strategies.
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# Spatial Priming Outperforms Semantic Prompting: A Grid-Based Approach to Improving LLM Accuracy on Chart Data Extraction Source: [https://arxiv.org/abs/2605.08220](https://arxiv.org/abs/2605.08220) [View PDF](https://arxiv.org/pdf/2605.08220) > Abstract:The automated extraction of data from scientific charts is a critical task for large\-scale literature analysis\. While multimodal Large Language Models \(LLMs\) show promise, their accuracy on non\-standardized charts remains a challenge\. This raises a key research question: what is the most effective strategy to improve model performance \(high\-level semantic priming\) or low\-level spatial priming? This paper presents a comparative investigation into these two distinct strategies\. We describe our exploratory experiments with semantic methods, such as a two\-stage metadata\-first framework and Chain\-of\-Thought, which failed to produce a statistically significant improvement\. In contrast, we present a simple but highly effective spatial priming method: overlaying a coordinate grid onto the chart image before analysis\. Our quantitative experiment on a synthetic dataset demonstrates that this grid\-based approach provides a statistically significant reduction in data extraction error \(SMAPE reduced from 25\.5% to 19\.5%, p < 0\.05\) compared to a baseline\. We conclude that for the current generation of multimodal models, providing explicit spatial context is a more effective and reliable strategy than high\-level semantic guidance for this class of tasks\. ## Submission history From: Andrei Lazarev \[[view email](https://arxiv.org/show-email/4329bd06/2605.08220)\] **\[v1\]**Wed, 6 May 2026 13:38:29 UTC \(476 KB\)
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