Oscar William Lithgow-Serrano

Also published as: Oscar William Lithgow Serrano, Oscar William Lithgow-Serrano


2025

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Causal Understanding by LLMs: The Role of Uncertainty
Oscar William Lithgow-Serrano | Vani Kanjirangat | Alessandro Antonucci
Proceedings of the 2nd Workshop on Uncertainty-Aware NLP (UncertaiNLP 2025)

Recent papers show LLMs achieve near-random accuracy in causal relation classification, raising questions about whether such failures arise from limited pretraining exposure or deeper representational gaps. We investigate this under uncertainty-based evaluation, testing whether pretraining exposure to causal examples improves causal understanding using >18K PubMed sentences—half from The Pile corpus, half post-2024—across seven models (Pythia-1.4B/7B/12B, GPT-J-6B, Dolly-7B/12B, Qwen-7B). We analyze model behavior through: (i) causal classification, where the model identifies causal relationships in text, and (ii) verbatim memorization probing, where we assess whether the model prefers previously seen causal statements over their paraphrases. Models perform four-way classification (direct/conditional/correlational/no-relationship) and select between originals and their generated paraphrases. Results show almost identical accuracy on seen/unseen sentences (p>0.05), no memorization bias (24.8% original selection), output distribution over the possible options almost flat — with entropic values near the maximum (1.35/1.39), confirming random guessing. Instruction-tuned models show severe miscalibration (Qwen: >95% confidence, 32.8% accuracy, ECE=0.49). Conditional relations induce highest entropy (+11% vs direct). These findings suggest that failures in causal understanding arise from the lack of structured causal representation, rather than insufficient exposure to causal examples during pretraining.

2024

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Comparing panic and anxiety on a dataset collected from social media
Sandra Mitrović | Oscar William Lithgow-Serrano | Carlo Schillaci
Proceedings of the 9th Workshop on Computational Linguistics and Clinical Psychology (CLPsych 2024)

The recognition of mental health’s crucial significance has led to a growing interest in utilizing social media text data in current research trends. However, there remains a significant gap in the study of panic and anxiety on these platforms, despite their high prevalence and severe impact. In this paper, we address this gap by presenting a dataset consisting of 1,930 user posts from Quora and Reddit specifically focusing on panic and anxiety. Through a combination of lexical analysis, emotion detection, and writer attitude assessment, we explore the unique characteristics of each condition. To gain deeper insights, we employ a mental health-specific transformer model and a large language model for qualitative analysis. Our findings not only contribute to the understanding digital discourse on anxiety and panic but also provide valuable resources for the broader research community. We make our dataset, methodologies, and code available to advance understanding and facilitate future studies.

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Leveraging LLMs to Enhance Clinical Record Analysis and Retrieval
Lorenzo Ruinelli | Amos Colombo | Oscar William Lithgow Serrano | Andrea Franchini | Joseph Cornelius | Sandra Mitrovic | Fabio Rinaldi
Proceedings of the 9th edition of the Swiss Text Analytics Conference

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NLP in support of Pharmacovigilance
Fabio Rinaldi | Lorenzo Ruinelli | Roberta Noseda | Oscar William Lithgow Serrano | Sandra Mitrovic
Proceedings of the 9th edition of the Swiss Text Analytics Conference

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Personalized and Interactive Education in Migraine using Artificial Intelligence
Fabio Rinaldi | Oscar William Lithgow Serrano | Andrea Franchini | Chiara Zecca | Giulia Mallucci | Alberto Cordella
Proceedings of the 9th edition of the Swiss Text Analytics Conference

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Presenting BUST - A benchmark for the evaluation of system detectors of LLM-Generated Text
Joseph Cornelius | Oscar William Lithgow Serrano | Sandra Mitrović | Ljiljana Dolamic | Fabio Rinaldi
Proceedings of the 9th edition of the Swiss Text Analytics Conference

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What can we discover about panic and anxiety from bloggers in Quora and Reddit?
Sandra Mitrović | Oscar William Lithgow Serrano
Proceedings of the 9th edition of the Swiss Text Analytics Conference