Probing for Reading Times
Summary
The paper asks whether the hidden states of neural language models hold information about human reading behaviour beyond what the usual single-number predictor, surprisal, provides. The authors train regularized linear regression probes that map layer-wise representations onto three word-level eye-tracking measures: the duration of a word's first fixation, its gaze duration, and the overall time spent reading it. They use the Provo and MECO corpora, covering English, Greek, Hebrew, Russian and Turkish, with representations from mGPT, GPT-2 and cosmosGPT. Every layer is compared with three scalar baselines: surprisal, information value and logit-lens surprisal.
For early-pass measures, especially in English, representations from early layers predict reading times better than surprisal. This hints that model depth roughly mirrors the time course of human reading. For total reading time, compact surprisal is usually as good or better. Adding surprisal to the representations often helps. The best predictor depends heavily on the language and the measure. This matters for psycholinguistic modelling, because no single LM-derived feature works best in every setting.
Key points
- Data: the Provo and MECO eye-tracking corpora, five languages (English, Greek, Hebrew, Russian, Turkish).
- Models: mGPT (up to 1.3B parameters, the largest model tested), GPT-2 and cosmosGPT. Multi-token units are represented by mean-pooled hidden states.
- Early-layer representations beat surprisal on first fixation and gaze duration. Scalar surprisal and logit-lens surprisal stay competitive or superior for total reading time, and often in the non-English languages.
- Evaluation uses raw MSE with permutation testing to control for chance associations. Representations vary more across layers than information value or logit-lens surprisal do.
- Code is available at github.com/rycolab/llm-representations-rt. Stated limitations include eye-tracking data only, no randomly initialized model baselines, and no dimensionality reduction (e.g., PCA).
Topics Psycholinguistics & language acquisition Interpretability
Institutions
Cite
Cite as Eleftheria Tsipidi, Samuel Kiegeland, Francesco Ignazio Re, Tianyang Xu, Mario Giulianelli, Karolina Stanczak and Ryan Cotterell. 2026. Probing for Reading Times. Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers).
@inproceedings{tsipidi2026probing,
title = {{Probing for Reading Times}},
author = {Eleftheria Tsipidi, Samuel Kiegeland, Francesco Ignazio Re, Tianyang Xu, Mario Giulianelli, Karolina Stanczak and Ryan Cotterell},
booktitle = {Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)},
year = {2026},
doi = {10.18653/v1/2026.acl-long.575},
url = {https://doi.org/10.18653/v1/2026.acl-long.575}
}References
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