Context effects on saccade-related brain potentials to words during reading.

In two experiments saccade-related brain potentials (SRPs) to sentences were investigated under conditions approximating natural reading. Our aim was to look for electrophysiological (SRP) signs of sentence context on the processing of final words that were either congruent or incongruent with the meaning of the sentence. In Experiment 1 subjects indicated by a button-press whether or not the final word was congruent with the context, while in Experiment 2 they read silently without an overt decision. In Experiment 1, SRPs to incongruent words were more negative than SRPs to congruent words between 80-310 msec (from saccade offset). In Experiment 2, however, the inconcruent SRPs became more negative than the congruent SRPs only between 280-460 msec. These results suggest that in Experiment 1, during the processing of incongruent words the early sign of registering mismatch appears simultaneously with the analysis of the visual features of the word.