Ruchira Dhar

Author directory

2026

Compositionality is considered central to language abilities. As performant language systems, how do large language models (LLMs) do on compositional tasks? We evaluate adjective–noun compositionality in LLMs using two complementary setups: prompt-based functional assessment and a representational analysis of internal model states. Our results reveal a striking divergence between task performance and internal states. While LLMs reliably develop compositional representations, they fail to translate consistently into functional task success across model variants. Consequently, we highlight the importance of contrastive evaluation for obtaining a more complete understanding of model capabilities.
The application of Item Response Theory (IRT) for data selection in benchmarks has mostly been limited to monolingual settings. In this work, we ask: how does IRT generalize when the same benchmark is translated across languages? We conduct experiments on Multilingual GSM and Global MMLU, covering over 100 language models and 11 languages. Fitting 1PL, 2PL, and 3PL IRT models per language, we assess cross-lingual consistency of parameters and whether IRT-filtered subsets preserve model rankings across languages: item *difficulty* emerges as the most stable parameter followed by *guessing* and *discrimination*. A differential item analysis also shows that lack of stability can be tracked to specific items shifting under translation across languages. Our findings suggest IRT-based selection in multilingual settings must be both parameter-aware and item-aware, validating model choice and screening individual items before assuming cross-lingual generalization.

2025

This paper explores the effectiveness of Multimodal Large Language models (MLLMs) as assistive technologies for visually impaired individuals. We conduct a user survey to identify adoption patterns and key challenges users face with such technologies. Despite a high adoption rate of these models, our findings highlight concerns related to contextual understanding, cultural sensitivity, and complex scene understanding, particularly for individuals who may rely solely on them for visual interpretation. Informed by these results, we collate five user-centred tasks with image and video inputs, including a novel task on Optical Braille Recognition. Our systematic evaluation of twelve MLLMs reveals that further advancements are necessary to overcome limitations related to cultural context, multilingual support, Braille reading comprehension, assistive object recognition, and hallucinations. This work provides critical insights into the future direction of multimodal AI for accessibility, underscoring the need for more inclusive, robust, and trustworthy visual assistance technologies.

2024

Knowledge claims are abundant in the literature on large language models (LLMs); but can we say that GPT-4 truly “knows” the Earth is round? To address this question, we review standard definitions of knowledge in epistemology and we formalize interpretations applicable to LLMs. In doing so, we identify inconsistencies and gaps in how current NLP research conceptualizes knowledge with respect to epistemological frameworks. Additionally, we conduct a survey of 100 professional philosophers and computer scientists to compare their preferences in knowledge definitions and their views on whether LLMs can really be said to know. Finally, we suggest evaluation protocols for testing knowledge in accordance to the most relevant definitions.