ORIGINAL RESEARCH article
Front. Psychol.
Sec. Psychology of Language
This article is part of the Research TopicInsights in Psycholinguistics: 2025View all 4 articles
Successive-Cyclic Movement in Humans and Neural Language Models: Testing Wh-Filler-Gap Dependencies
Provisionally accepted
Keonwoo Koo1
Hyosik Kim2*- 1Department of English Language and Literature, Dongguk University, Seoul, Republic of Korea
- 2Department of English Language and Literature, Jeonju University, Jeonju, Republic of Korea
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This study investigates whether auto-regressive language models (GPT-2, GPT-Neo, OPT) replicate human-like sensitivity to covert intermediate phrasal structures (CP vs. NP) during the processing of wh-filler-gap dependencies. We extend this inquiry to backward sluicing, an elliptical construction that provides a robust test for the representation of abstract syntactic structure. Across two experiments measuring processing difficulty via surprisal, we found a significant divergence from established human processing patterns. We found that the models failed to reproduce the human processing facilitation for both canonical and elided dependencies. One model, in fact, showed an inverse effect, a pattern suggesting a reliance on surface-level cues rather than abstract hierarchical representations. We take these findings as evidence that the tested GPT-style models are insufficient for deriving knowledge of covert syntactic structures. This failure lends empirical support to the Poverty of the Stimulus (PoS) argument, and also highlights a significant gap in the cognitive plausibility of contemporary NLMs as models of human syntactic competence.
Keywords: backward sluicing, Intermediate structure, Neural language models, Poverty of stimulus, successive-cyclic movement, Wh-filler-gap dependency
Received: 09 Dec 2025; Accepted: 09 Dec 2025.
Copyright: © 2025 Koo and Kim. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Hyosik Kim
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