Revisiting Real-Time Digging-In Effects: No Evidence from NP/Z Garden-Paths
This addresses a theoretical debate in psycholinguistics about self-organized versus statistical models of sentence processing, but is incremental as it refines existing evidence without introducing new methods.
The study tackled the problem of whether digging-in effects are a real-time phenomenon in human sentence processing by conducting experiments on English NP/Z garden-path sentences using Maze and self-paced reading, and found no evidence for such effects, with positive trends only appearing sentence-finally where wrap-up effects confound interpretation.
Digging-in effects, where disambiguation difficulty increases with longer ambiguous regions, have been cited as evidence for self-organized sentence processing, in which structural commitments strengthen over time. In contrast, surprisal theory predicts no such effect unless lengthening genuinely shifts statistical expectations, and neural language models appear to show the opposite pattern. Whether digging-in is a robust real-time phenomenon in human sentence processing -- or an artifact of wrap-up processes or methodological confounds -- remains unclear. We report two experiments on English NP/Z garden-path sentences using Maze and self-paced reading, comparing human behavior with predictions from an ensemble of large language models. We find no evidence for real-time digging-in effects. Critically, items with sentence-final versus nonfinal disambiguation show qualitatively different patterns: positive digging-in trends appear only sentence-finally, where wrap-up effects confound interpretation. Nonfinal items -- the cleaner test of real-time processing -- show reverse trends consistent with neural model predictions.