A P600 component in an artificial grammar without semantics: an EEG study of structural violation type

TABULLO, ÁNGEL; SEVILLA, YAMILA; PASQUALETTI, GUILLERMO; YORIO, ALBERTO; ZANUTTO, SILVANO; WAINSELBOIM, ALEJANDRO

Kobe

Congreso; ICCN 2010: 29th International Congress of Clinical Neurophysiology; 2010

International Federation of Clinical Neurophysiology

The P600 component is a late positivity found after syntactic anomaliesin sentences (Osterhout and Holcomb 1992) So far, it has not beenaddressed if the P600 is found after violations of an artificial grammarwithout semantic content, based solely on statistic information. Theaims of the present study were: (1) To examine the presence of P600after structural violations of a semantic-free artificial grammar based onstatistical information; (2) to examine if the type of structural violationaffects the P600 component.Methods: 21 right-handed Spanish native speakers participated inthe study. A semantic-free artificial grammar was used. The lexiconconsisted of 17 bisillabic, phonotactically correct pseudowords. Thegrammar admitted two possible sentence structures. Subjects weretrained by mere exposure with a set of 90 correct sentences, and thendiscriminated between grammatical and ungrammatical new sentences inthe test stage. Two types of ungrammatical sentences were presented:(a) conjunction violation (presenting a connector from structure 1 in asentence with structure 2), (b) category violation (presenting an itemfrom an incorrect category at the end of the sentence). EEG activity wasrecorded during test stage.Results: A late centro-parietal positivity was observed within 600900 ms after grammar violations. The difference between grammaticaland ungrammatical sentences was significant (F(1,20) = 7.015; p = 0.016).A further ANOVA, discriminating between violation types, showed aregion × laterality × sentence type effect (F(16,304) = 2.647; p = 0.039).Category violations elicited greater positivities than grammaticalsentences. No differences were found between conjunction violations.Discussion: Results suggests that the P600 can be elicited by expectancyviolations based on distributional properties of input. The effect wasmore clearly observed after category violations. It is possible that thistype of violation was more salient, as it was located at the end of thesentence.