Types of conflict-resolution and their EEG-correlates

The central questions of the project are: (1) Are there EEG-correlates for possible vs.impossible conflict resolution during a violation of grammar in the EEG? (2) Is it possible to determine correlates of different conflict resolution activities in the frequency profile of the EEG (to functionally disambiguate ERPs)? So far, EEG-investigations of language processing focus on correlates of processing activities at different levels of grammar. However, given the preferential use of stimuli with grammatical violations in experiments, the observed processing activity will necessarily include conflict resolution. Therefore it is adequate to investigate if and how the type of conflict resolution plays a role, namely the type of conflict resolution in relation to grammatical alternatives: grammatically possible conflict resolution (there is a wellformed alternative) vs. grammatically impossible conflict resolution (there is no wellformed alternative). A positive result would not only have implications for psycho- and neurolinguistics but also for the theoretical modelling of linguistic knowledge in grammar theory. The issues at stake are experimentally tested with grammatically non dissolvable conflicts during the fronting of the finite verb in main clauses (with verbs having more than one separable prefix. Furthermore, previously gathered data are explored with frequencyanalytical methods that have proved successful in an already completed project ("Sentence production: EEG-oscillations during sentence processing", FWF) to gain additional EEG correlates for the differentiation of ERP-results: negativities (latency around 400 ms over centro-posterior regions) are established as reliable ERP-correlate for conflicts with semantic wellformedness. However, in a series of experiments the N400-effect could be found with conflicts that have their cause not or not unambiguously in the semantic domain of language perception, for instance conflicts of case, congruency, argument structure, negative polarity, word position. Viewed under the perspective of the knowledge system "grammar", these domains belong to different subsystems of syntax. Therefore the question is posed whether the observed N400-effect is a not further differentiatable, global reflex of an undifferentiated language controlled conflict processing activity or if it is possible to gain more specific processing correlates with more appropriate analytical techniques. Finally the applied frequency-analytical methods are evaluated and if necessary refined.

The central questions of the project were: (1) whether it is possible to dissociate different types of language-related conflict resolution in the frequency profile of the EEG, thereby allowing for a disambiguation of functionally ambiguous event-related brain potentials (ERPs), and (2) whether EEG-based measures can differentiate between possible and impossible conflict resolution in the processing of grammatical violations. The primary aim of the data-analytical part of the project was to provide a characterization of language-related neurophysiologic events by means of event-related frequency band analyses. In particular, this involved the frequency-specific analysis and classification of N400 effects found in ERP analyses. This component was originally regarded a reliable ERP-correlate of lexical-semantic processes. However, in a series of ERP- experiments, N400-effects have also been observed in response to non-semantic processing demands (conflicts of case, congruency, word position). This raises the question of whether the N400 should be considered a global reflex of undifferentiated language-related conflict processing or whether a further, more specific differentiation of different types of N400s can be achieved via frequency-analytical techniques. Our results suggest that conflicts stemming from processing difficulties in qualitatively different language domains can be attributed to activity in different frequency bands. Moreover, they show that functionally distinct processes which are not distinguishable by means of ERPs can be effectively disambiguated on the basis of their underlying frequency characteristics. Particularly the successful frequency-analytical dissociation of negativities in the time range of approx. 400 ms post stimulus onset that are triggered by different grammatical conflicts (semantic N400, N400 in case conflicts, animacy N400, N400 for word order variations) can be regarded as evidence for the basic hypothesis that a detailed analysis of the underlying frequency characteristics of ERP components leads to a better understanding of the processes involved. Regarding the second major question addressed in the project, our results show that a conflict situation engendered by a processing conflict leads to qualitatively different processes depending on the information available. Thus, conflict resolution activities can be dissociated by means of their underlying dynamic EEG-frequency characteristics (phase-coupling vs. power modulation) depending on whether they are resolvable or not. Therefore, the frequency-analytical characterization of EEG correlates applied here opens up new perspectives for the description and classification of the neural basis of cognitive processes.