Authors:

Penolazzi, B., HAUK, O. & PULVERMULLER, F.

Reference:

Year of publication:

2007

CBU number:

6275

Abstract:

A late neurophysiological response, the N400, is well-known to reflect word processing and semantic context integration. Nevertheless, behavioural data have demonstrated that word features and semantic sentence context influence linguistic processes already within the first 200 ms following the onset of the critical word. The lack of early word-related ERP effects in some studies might be due to large stimulus variance on relevant linguistic parameters, for example the length of written words or their frequency of usage. Here we investigated the effect of the Length of words, their standardised lexical Frequency and Probability to occur in a given semantic context, by orthogonally varying these factors in a sentence reading task. We found word Frequency and Probability to be reflected neurophysiologically already at 120 ms and 180 ms after written word onset. However, at these early stages Frequency and Probability effects were modulated by word Length, as documented by significant interactions, whereas at later stages, around 300-500 ms, additive effects of these variables were found. These results indicate that semantic context integration may take place at a surprisingly early stage, therefore challenging serial models of psycholinguistic information access. A methodological implication of this study is that, in order to obtain early psycholinguistic ERP effects, stimulus variance must be kept to a minimum.