g. a specific incongruence of functional elements such as agreement or tense markers), while in the latter, violations arise in virtue of one token being incompatible in its inherent meaning with surrounding tokens. In addition, semantic anomalies may be less categorical in that, unless they are deeply implausible, they are less likely to be classified as outright violations (Coulson et al., 1998a). Accordingly, it appears reasonable that LDK378 order P600 effects are
somewhat more likely to occur in response to (morpho-)syntactic as opposed to semantic violations (but see Section 1.2 for a discussion of P600 effects elicited by semantic incongruities). In testing a critical entailment
of the P600-as-LC/NE-P3 theory, we found that the late positivity following morphosyntactic violations behaved like a P3 in being response-aligned. Even though subjects successfully processed semantic content and syntactic structure, no distinct, stimulus-locked late positivity was observed. This result is predicted by all accounts which subscribe to the P600-as-P3 assumption, but requires additional post hoc assumptions for typical interpretations of the P600 as a distinct component reflecting the analysis, reanalysis or repair of linguistic input. While these results do not prove the P600-as-P3 hypothesis, they confirm a necessary entailment PCI-32765 mw of this theory (particularly of the stronger, else P600-as-LC/NE-P3 hypothesis), and any other finding would have strongly supported the hypothesis of a distinct P600 component. Furthermore, we have demonstrated the feasibility of single-trial analysis techniques informed by immediate behavioural responses during stimulus presentation. Our findings show that single-trial analyses of sentence processing
data can be used to inform models of the neurobiology of language. Lastly, we would like to reiterate a point previously made by Coulson et al. (1998a). Understanding the P600 as a type of P3 (i.e. as being traceable to the same underlying neurobiological system) does not automatically devalue it as a tool for the investigation of the neural substrates of language processing. If our interpretation of the late positivity in sentence processing experiments as an LC/NE-P3 is correct, this component marks a point in time where a linguistic entity has achieved subjective significance and some form of adaption process is underway. Its amplitude marks the degree to and reliability with which this stimulus class is significant. It thereby provides a gradient (though indirect, relative) measure for the time course of certain processes.