Poster #: 106
Topic: Speech and language (incl. deficits)
Wednesday, Sep 9, 2015
Language-attention interactions in neural processing of spoken words
1Donders Institute, Nijmegen, Netherlands
Previous studies indicated diverging patterns of ERP responses to meaningful and meaningless lexical materials: stronger MMN for words vs. pseudowords, and the opposite pattern (pseudowords> words) for N400 responses. Possible reasons include stimulation regime (repetitive oddball stimulation vs. multiple unrepeated stimuli) and/or the level of attention on linguistic input (passive presentation vs. active tasks). To address this, we recorded MMNs to word and pseudoword stimuli, while participants attended to either these stimuli or to a nonlinguistic task.
The results showed an MMN peaking at ~130ms after the word recognition point, followed by a shift in the classical N400 window. In the early window, a strong effect of attention – larger MMN for attended than unattended stimuli – was localised to left-frontal sites. In right-frontal electrodes, however, we found an interaction between attention and lexicality: while word MMNs were relatively immune to attentional modulation, pseudoword responses increased with attention. In the N400 window, attention enhanced all responses. Furthermore, a contrast between pseudoword and word ERPs showed a typical N400 effect (pseudoword>word), present only in attend conditions.
The results demonstrate a complex pattern of language-attention interactions in neural word comprehension processes. Early on, word responses appear more robust, while pseudoword ERPs are subject to stronger attention modulation. Later on, attention effects are more pervasive. We also show that N400 effects can be elicited in MMN designs, and are thus resilient to multiple stimulus repetition. They are, however, limited to attend conditions and therefore likely reflect top-down controlled processes in lexical access.