When Language Models Lose Their Mind: The Consequences of Brain Misalignment

Fuente: arXiv
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Auteurs principaux: Merlin, Gabriele, Toneva, Mariya
Format: Preprint
Publié: 2026
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author Merlin, Gabriele
Toneva, Mariya
author_facet Merlin, Gabriele
Toneva, Mariya
contents While brain-aligned large language models (LLMs) have garnered attention for their potential as cognitive models and for potential for enhanced safety and trustworthiness in AI, the role of this brain alignment for linguistic competence remains uncertain. In this work, we investigate the functional implications of brain alignment by introducing brain-misaligned models--LLMs intentionally trained to predict brain activity poorly while maintaining high language modeling performance. We evaluate these models on over 200 downstream tasks encompassing diverse linguistic domains, including semantics, syntax, discourse, reasoning, and morphology. By comparing brain-misaligned models with well-matched brain-aligned counterparts, we isolate the specific impact of brain alignment on language understanding. Our experiments reveal that brain misalignment substantially impairs downstream performance, highlighting the critical role of brain alignment in achieving robust linguistic competence. These findings underscore the importance of brain alignment in LLMs and offer novel insights into the relationship between neural representations and linguistic processing.
format Preprint
id arxiv_https___arxiv_org_abs_2603_23091
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle When Language Models Lose Their Mind: The Consequences of Brain Misalignment
Merlin, Gabriele
Toneva, Mariya
Computation and Language
While brain-aligned large language models (LLMs) have garnered attention for their potential as cognitive models and for potential for enhanced safety and trustworthiness in AI, the role of this brain alignment for linguistic competence remains uncertain. In this work, we investigate the functional implications of brain alignment by introducing brain-misaligned models--LLMs intentionally trained to predict brain activity poorly while maintaining high language modeling performance. We evaluate these models on over 200 downstream tasks encompassing diverse linguistic domains, including semantics, syntax, discourse, reasoning, and morphology. By comparing brain-misaligned models with well-matched brain-aligned counterparts, we isolate the specific impact of brain alignment on language understanding. Our experiments reveal that brain misalignment substantially impairs downstream performance, highlighting the critical role of brain alignment in achieving robust linguistic competence. These findings underscore the importance of brain alignment in LLMs and offer novel insights into the relationship between neural representations and linguistic processing.
title When Language Models Lose Their Mind: The Consequences of Brain Misalignment
topic Computation and Language
url https://arxiv.org/abs/2603.23091