The P600 as an index of syntactic integration difficulty

The P600 component in Event Related Potential research has been hypothesise d to be associated with syntactic reanalysis processes. We, however, propos e that the P600 is not restricted to reanalysis processes, but reflects dif ficulty with syntactic integration processes in general. First we discuss t his integration hypothesis in terms of a sentence processing model proposed elsewhere. Next, in Experiment 1, we show that the P600 is elicited in gra mmatical, non-garden path sentences in which integration is more difficult (i.e., "who" questions) relative to a control sentence ("whether" questions ). This effect is replicated in Experiment 2. Furthermore, we directly comp are the effect of difficult integration in grammatical sentences to the eff ect of agreement violations. The results suggest that the positivity elicit ed in "who" questions and the P600-effect elicited by agreement violations have partly overlapping neural generators. This supports the hypothesis tha t similar cognitive processes, i.e., integration, are involved in both firs t pass analysis of "who" questions and dealing with ungrammaticalities (rea nalysis).