As a contribution to the controversy over the purely formal nature vs. semantic dimension of syntactic constructions, in a joint work with neuroscientists, we conducted an experiment using electrophysiology (Event Related Potentials) in order to determine (1) whether the semantic aspects of language are processed (by the brain) independently or in interaction with the syntax, (2) what contribution the transitive construction makes to the meaning of the sentence. To test these points, we manipulated both the syntactic and semantic components in transitive constructions in French, using « transitive coercion » (a transitive construction was applied to an intransitive verb such as 'to conspire' or 'to lunch') and manipulating the semantic component by applying an object that was semantically either congruent (L’ennemi a conspiré un complot ‘The enemy conspired a scheme’) or incongruent (L’ennemi a déjeuné un complot ‘The enemy lunched a scheme’) with the semantics of the verb. We hypothesized that if semantic information is used on-line during sentence comprehension and interacts with syntax, the strong semantic relationship between the verb and direct object in L’ennemi a conspiré un complot (The enemy conspired a scheme) may override the problem posed by the syntactic incongruity. In order to maximize the semantic congruence of the sentence context, strong semantic associations were present not only between the verb and the object (an internal object, as is a ‘scheme’ for the verb ‘conspire’), but also between the subject and the verb (e.g. the noun ‘enemy’ is a prototypical subject for ‘conspire’). In our linguistic experiment, two main electrophysiological components were at work: the N400, classically considered to reflect difficulties in semantic processing, and the P600, supposed to reflect difficulties in syntactic processing. The analysis of the ERPs elicited by the different types of SVO sentences (with vs. without syntactic coercion, combined with semantic congruence vs. incongruence) in our experiment clearly indicated that the processing of semantic information influences syntactic processing: in line with our hypothesis, the ERP’s results showed that the brain does not detect the syntactic violation (no P600 component) when the sentence makes sense. We then give a linguistic account of these results based on Construction Grammar and Frame Semantics (Fillmore 1982, Fillmore 2012, Goldberg 1995), and argue for constructionist approach to 'coercion' (Michaelis 2004). Moreover, to further examine the respective contribution of the subject-verb and verb-object relationships, in a second experiment we reduced the subject-verb semantic associations: the prototypical subject of the sentences was replaced by a semantically neutral proper name (e.g., Thomas), while keeping the same semantic associations between the verb and the object. Remarkably, the syntactic incongruity in the verb-object relation was detected this time, revealing an interesting graduality of the overall semantic context, with threshold effects. References Fillmore Charles. 1982. Frame Semantics. In Linguistic Society of Korea (ed.), Linguistics in the Morning Calm. Seoul: Hanshin, 111-138. Goldberg Adele. 1995. Constructions. A construction grammar approach to argument structure. Chicago/London: The University of Chicago Press. Kutas M. & Hillyard S. A. 1980. Reading senseless sentences: brain potentials reflect semantic incongruity. Science 207: 203–204. Magne Cyrille, Besson Mireille & Robert Stéphane. 2014. Context influences the processing of verb transitivity in French sentences: more evidence for semantic-syntax interactions, Language and Cognition 6/2: 181-216. Michaelis L. 2004. Word meaning, sentence meaning, and syntactic meaning. In H. Cuykens, R. Dirven & J. R. Taylor (Eds.), Cognitive approaches to lexical semantics. Berlin/New York : Mouton de Guyter, 163-210. Michaelis Laura A. 2004. Type-shifting in Construction Grammar: An Integrated Approach to Aspectual Coercion. Cognitive Linguistics 15 (1): 1–67. Osterhout L. & Holcomb P. J. 1992. Event-Related brain potentials elicited by syntactic anomaly. Journal of Memory and Language 31: 785 – 804. Robert S. 1999. Cognitive invariants and linguistic variability: from units to utterance . In C. Fuchs & S. Robert (Eds.), Language diversity and cognitive representations. Amsterdam/Philadelphia : John Benjamins, 21-35.