Priming of transparent derived verbs in L2 speakers: An fMRI study

In this fMRI long-lag priming study, we investigated the processing of Dutch semantically transparent, morphologically complex derived verbs. In such words, the meaning of the word as a whole can be deduced from the meanings of its parts, e.g. wegleggen ‘put aside’. Native (L1) speakers have been found to decompose transparent complex words in many behavioral and some fMRI studies [1,2]. The brain region usually implicated in morphological decomposition is the left inferior frontal gyrus (LIFG). In a previous fMRI long-lag priming study, this region was found to be deactivated upon presentation of the primed word of a morphologically related word pair [2]. In non-native (L2) speakers, the processing of transparent derived words has hardly been investigated, especially in fMRI studies, and results are contradictory: Some behavioral studies have found more reliance on holistic processing by L2 speakers [3]; some have found no difference between L1 and L2 speakers [4]. In this study, we wanted to find out whether Dutch transparent derived verbs are decomposed or processed holistically by L2 speakers and a control group of L1 speakers. Half of the derived verbs (e.g. omvallen ‘fall down’) were preceded by their stem (e.g. vallen ‘fall’) with a lag of 4 to 6 words (‘Primed’); the other half (e.g. inslapen ‘fall asleep’) were not (‘Unprimed’). Eighteen Dutch L1 speakers and 21 German L2 speakers of Dutch made lexical decisions on these visually presented verbs. A ROI analysis over both groups showed that there was significant deactivation for Primed compared to Unprimed derived verbs in the LIFG. Even though the interaction between Priming and Language Group was not significant, a closer look at the data showed that this effect was large and statistically significant for the L2 group alone, but not for L1 speakers alone (although they did show the same pattern descriptively). The results of the ROI analyses were confirmed in awhole-brain analysis. Thus, L2 speakers show a clear priming effect in the LIFG, whereas the evidence for a priming effect in L1 speakers is less clear. As mentioned before, the LIFG has been associated with morphological decomposition. Our finding of LIFG deactivation in L2 speakers is consistent with the idea that L2 speakers decompose morphologically complex verbs rather than processing them holistically. Results will be discussed in the context of the available behavioral and neuroimaging data on the processing of morphologically complex words in L1 and L2 speakers. References: [1] Marslen- Wilson, W. D., Tyler, L. K., Waksler, R., & Older, L. (1994). Morphology and meaning in the English mental lexicon. Psychological Review, 101(1), 3-33. [2] Bozic, M., Marslen-Wilson, W.D., Stamatakis, E.A., Davis, M.H., & Tyler, L. (2007). Differentiating morphology, form, and meaning: Neural correlates of morphological complexity. Journal of Cognitive Neuroscience, 19(9), 1464-1475. [3] Clahsen, H., & Neubauer, K. (2010). Morphology, frequency, and the processing of derived words in native and non-native speakers. Lingua, 120(11), 2627-2637. [4] Portin, M., & Laine, M. (2001). Processing cost associated with inflectional morphology in bilingual speakers. Bilingualism: Language and Cognition, 4(1), 55-62