Comparative illusions are evidence of rational inference in language comprehension.

Sometimes sentences sound acceptable when they are ungrammatical or semantically implausible. In this article, we study "comparative illusion" (CI) sentences where people often rate a sentence like to be acceptable while in fact it is semantically anomalous. We provide a potential explanation for this language illusion from the noisy-channel framework. We hypothesize that comprehenders make rational inferences over the perceived sentence by entertaining alternative "close" plausible interpretations, where closeness is determined by possible production errors. In four experiments, (a) we identified a linguistic construction that elicits a salient CI illusion effect, (b) we established a range of plausible interpretations of the CI sentence, and (c) we found that the probability for comprehenders to assign a certain plausible interpretation to the CI sentence is proportional to how likely they think that interpretation is to be produced as the CI sentence during noisy language communication. This work contributes to a growing body of literature supporting rational noisy-channel inference during language comprehension. (PsycInfo Database Record (c) 2025 APA, all rights reserved).