Context ameliorates but does not eliminate garden-pathing: Novel insights from latent-process modeling

A theoretically important claim in psycholinguistics is that in English, linguistic context largely eliminates garden-path effects in temporary complement clause/relative clause ambiguities (e.g., Altmann, Garnham, and Dennis, 1992, Avoiding the garden path: Eye movements in context. Journal of Memory and Language, 31 (5), 685-712). However, this strong claim, based on comparing mean differences between groups of conditions in a factorial design, reduces the conclusion to a overly simplistic binary one: either context affects garden-pathing or it doesn't. Mean differences are an aggregate of different, non-deterministic parsing steps that could be very different from trial to trial. As a result, there may not be a simple yes-no answer to whether context eliminates garden-pathing. Sentence comprehension has been argued to involve a cascade of probabilistically occurring latent processes (e.g., Paape and Vasishth, 2022); seen in this way, context-sensitivity may only be occurring probabilistically and in a graded manner. We present a hierarchical multinomial processing tree model that spells out several probabilistic latent processes. The model reveals new insights into the impact of context on garden-pathing, going beyond the simple question of whether context reduces processing difficulty on average. Modeling using new data from a bidirectional self-paced reading study with 319 participants shows that the context affects both first-pass attachment probability and reanalysis cost. Because a simpler account of context effects than the MPT model could be a model based on surprisal derived from large language models, we compare the MPT model's predictive fit to a model using surprisal computed from large language models. Results show that the MPT model, which assumes a mixture distribution of reading times, outperforms surprisal-based models at predicting garden-path effects.