Readers' eye movements distinguish anomalies of form and content.

Evidence is presented that eye-movement patterns during reading distinguish costs associated with the syntactic processing of sentences from costs associated with relating sentence meaning to real world probabilities. Participants (N = 30) read matching sets of sentences that differed by a single word, making the sentence syntactically anomalous (but understandable), pragmatically anomalous, or non-anomalous. Syntactic and pragmatic anomaly each caused perturbations in eye movements. Subsequent to the anomaly, the patterns diverged. Syntactic anomaly generated many regressions initially, with rapid return to baseline. Pragmatic anomaly resulted in lengthened reading times, followed by a gradual increase in regressions that reached a maximum at the end of the sentence. Evidence of rapid sensitivity to pragmatic information supports the use of timing data in resolving the debate over the autonomy of linguistic processing. The divergent patterns of eye movements support indications from neurocognitive studies of a principled distinction between syntactic and pragmatic processing procedures within the language processing mechanism.