Word Trigram Frequency Predicts Failure to Detect Word Transpositions: Implications for Rational Inference in Reading

A substantial recent literature has investigated readers' failure to detect transposed words in otherwise grammatical sentences. This phenomenon may reflect a process of rational inference, whereby a reader's prior over word strings overrides the bottom-up perceptual evidence. In three experiments, we tested the prediction emerging from the rational inference framework that failure to detect a transposition should be most common when the prior probability of the untransposed string is high. We found that the frequency of the trigram consisting of the two transposed words and the preceding word predicts failure to notice the transposition: Readers are more likely to miss a transposition of the final two words of a high-frequency trigram such as close the gate than a lower-frequency trigram such as close the pool. We also found a weaker role for the conditional probability of the transposed words based on the entire preceding sentence context. The results support a role for rational inference in 'correcting' errors, and also contribute further evidence that multi-word units play an important role in language processing.