Estimating the True Cost of Garden Pathing: A Computational Model of Latent Cognitive Processes

Abstract

What is the processing cost of being garden-pathed by a temporary syntactic ambiguity? We argue that comparing average reading times in garden-path versus non-garden-path sentences is not enough to answer this question. Trial-level contaminants such as inattention, the fact that garden pathing may occur non-deterministically in the ambiguous condition, and "triage" (rejecting the sentence without reanalysis; Fodor & Inoue, 2000) lead to systematic underestimates of the true cost of garden pathing. Furthermore, the "pure" garden-path effect due to encountering an unexpected word needs to be separated from the additional cost of syntactic reanalysis. To get more realistic estimates for the individual processing costs of garden pathing and syntactic reanalysis, we implement a novel computational model that includes trial-level contaminants as probabilistically occurring latent cognitive processes. The model shows a good predictive fit to existing reading time and judgment data. Furthermore, the latent-process approach captures differences between noun phrase/zero complement (NP/Z) gardenpath sentences and semantically biased reduced relative clause (RRC) garden-path sentences: The NP/Z garden path occurs nearly deterministically but can be mostly eliminated by adding a comma. By contrast, the RRC garden path occurs with a lower probability, but disambiguation via semantic plausibility is not always effective.

Surprisal does not explain syntactic disambiguation difficulty: evidence from a large-scale benchmark

“…They showed that while surprisal correctly predicted that reading times on the boldfaced words in (1a) are longer than the reading times on the same words in (1b), it predicted a much smaller excess processing difficulty on (1a) than empirically observed (for similar results for other linguistic constructions, obtained using the maze task, see Wilcox et al 2021). Such substantial underestimation of processing difficulty by surprisal may indicate that additional processes, such as syntactic reanalysis (Fodor and Ferreira, 1998;Paape and Vasishth, 2022), are recruited during the comprehension of syntactically complex sentences.…”