The 'Arrow of Time' effect: LLMs are better at predicting what comes next than what came before
Sep 2024, phys.org
Their performance at predicting the previous word is always a few percent worse than at predicting the next word. This phenomenon is universal across languages, and can be observed with any large language model.""In theory, there should be no difference between the forward and backward directions, but LLMs appear to be somehow sensitive to the time direction in which they process text. Interestingly, this is related to a deep property of the structure of language that could only be discovered with the emergence of large language models in the last five years."
via EPFL Ecole Polytechnique Federale de Lausanne: Vassilis Papadopoulos et al, Arrows of Time for Large Language Models, arXiv (2024). DOI: 10.48550/arxiv.2401.17505
Image credit: AI Art - Dental Implantology Services - 2024
Ouch! Study investigates pain vocalizations and interjections across 131 languages
Nov 2024, phys.org
Each of the three emotions yielded consistent and distinct vowel signatures across cultures. Pain interjections also featured similar open vowels, such as "a," and wide falling diphthongs, such as "ai" in "Ayyy!" and "aw" in "Ouch!"However, for disgusted and joyful emotions, in contrast to vocalizations, the interjections lacked regularities across cultures. The researchers expressed surprise at this latter finding.
Is this because disgust is cultural, or at least not entirely physical, and heavily mediated by culture, as compared to actual pain? This is commonly understood in the realm of olfactory perception, where some people think the smell of revolting, rotten fish is delicious (they're Norwegian). Or the smell of vomit (they're Italian, Parmesan to be specific), or the smell of the inside of the skin folds of a homeless person who hasn't been able to bathe in months (they're called New Yorkers, and they kind of long for the smell of the subway, which contains these volatiles). In fact, anything that's fermented is so close to rotten food, that unless you've been culturally conditioned to like it, you won't, at least not at first. Cilantro, I'm looking at you too.
via CNRS et Université Lumière Lyon, School of Social Sciences at University of Western Australia, and Institute of Psychology at University of Wrocław: Vowel signatures in emotional interjections and nonlinguistic vocalizations expressing pain, disgust and joy across languages, Journal of the Acoustical Society of America (2024). DOI: 10.1121/10.0032454
Words activate hidden brain processes shaping emotions, decisions and behavior
Jan 2025, phys.org
Words have meaning, but they also have emotional meaning:
"There's no single brain region handling this activity, and it's not as simple as one chemical representing one emotion."
(These studies were done thanks to the participation of patients being treated for epilepsy.)
The researchers discovered emotionally charged words - whether positive, negative, or neutral - modulate neurotransmitter release. By measuring the sub-second dynamics of the releases, they identified distinct patterns tied to emotional tone, anatomical regions, and which hemisphere of the brain was involved."The surprising result came from the thalamus. This region hasn't been thought to have a role in processing language or emotional content, yet we saw neurotransmitter changes in response to emotional words. This suggests that even brain regions not typically associated with emotional or linguistic processing might still be privy to that information. For instance, parts of the brain responsible for mobilizing movement might benefit from having access to emotionally significant information to guide behavior."
Note: The words used in the study were drawn from the Affective Norms for English Words (ANEW) database, which rates words by positive, negative, or neutral emotional valence.
via Virginia Tech School of Neuroscience and Fralin Biomedical Research Institute: Seth R. Batten et al, Emotional words evoke region- and valence-specific patterns of concurrent neuromodulator release in human thalamus and cortex, Cell Reports (2025). DOI: 10.1016/j.celrep.2024.115162
