de Diego-Balaguer, R.
ICREA, University of Barcelona
There is extensive evidence across languages with different morphological complexity that the retrieval of stems and grammatical features can be dissociated in functional and neuroanatomical terms. In second language acquisition these dissociations can also be observed. Morphosyntactic rules of a second language are particularly difficult to extract compared to L2 lexical acquisition. Aside from age of acquisition, other factors may have an effect in the extent of this difficulty. In this talk I will discuss the importance of two of these factors: the superficial similarity of the morphological transformations across languages and individual differences in the ability to orient attention to the relevant segments in speech. The first factor will be illustrated with a study with Catalan-Spanish bilinguals. Catalan and Spanish have a similar suffix (-o) for regular verbs and completely different alternations for irregular verbs. Two types of irregular verbs were studied (semi-regular verbs with a systematic diphthong alternation, sentir–siento, and verbs with idiosyncratic changes, venir–vengo). Regular verbs showed the same centro-parietal N400 priming effect in the second-language speakers (L2) as in primary-language (L1) speakers. However, differences between groups, in the ERP pattern and the topography of the N400 effect, were observed for irregular morphology. The importance of individual differences in attentional tunning will be illustrated with two event-related potentials experiments where we have been able to observe how this effect is specifically related to the generalisation of dependencies similar to morphological rules in comparison the word acquisition. We tracked the learning process recording electrophysiological changes while participants were learning an artificial language with non-adjacent embedded rules in the words (AXC: puliku, pusaku, pubeku) analogous to simple morphosyntactic rules (e.g.“is playing, isdancing, is talking”). The results indicated a functional dissociation between the brain responses associated to word and rule learning. While an increase in negativity (N400) in the central electrodes was related to word-learning, the development of a frontal positivity (P2) previously related to attentional modulations was correlated to rule-generalisation and accompanied by a synchronisation between frontal and parietal regions. The P2 modulation appeared only in those participants that learned the rule and even in the absence of external acoustic cues indicating its endogenous origin.