A preliminary investigation of dispositional affect, the P300, and sentence processing

We examined whether dispositional affect modulated the relation between sentence processing and the P300 Event Related Potential (ERP) component. We used sentence stimuli from our previous study, where sentences started with subject nouns that were quantified e.g., Every kid… or not, as in The kid…, and continued with a direct object which was either singular, as in a tree, or plural the trees. In this Stroop-like task, participants read sentences presented in 1- and 2-word chunks, and were asked to identify the number of words on the screen at the target word tree(s), which was always presented alone (and never sentence-final). We replicated previous findings of a P300 effect, at the target tree(s), however, actual by-condition effects differed from previous work. Of interest, clear individual differences were apparent. Participants with relatively lower Positive Affect scores (as measured by the Positive and Negative Affect Schedule; PANAS), showed differential P300 responses to the control condition, Every/The kid climbed the tree. Thus, the present ERP findings demonstrate that dispositional affect modulated P300 effects. These findings suggest that, rather than relying on global heuristic cues for sentence meaning interpretation, these participants may be differentially sensitive to local (grammatical) cues which signify task relevance. We discuss our results in terms of theories of positive affect, where less positive individuals are differentially sensitive to local (grammatical) information.