Extraction of Semantic Information from Parafoveal Words in the Reading of Chinese: An ERPs Study

Previous studies have confirmed that readers can obtain sub-lexical information (e.g., orthographic or phonological) from the parafovea during reading. However, no consensus has been reached as to whether semantic information can also be extracted from the parafoveal word. A possible explanation for this controversy may be the limitations of the boundary paradigm in eye-tracking reading experiments, which have been the main methodology used in previous studies. For instance, the duration of parafoveal word viewing cannot be held constant across conditions in the boundary paradigm. Thus, in this study, an ERPs paradigm using rapid serial visual presentation (RSVP) with ﬂ ankers was used to study extraction of semantic information from the parafoveal word in the reading of Chinese sentences. A total of 84 sets of Chinese sentences were constructed for this study. Unlike previous studies, in each set of sentences, the two-character verbs were manipulated, yielding a congruent or incongruent context with the target single-character noun that appeared 4 or 5 characters after the verbs. Thus the critical trials (containing the target noun as the right flanker) were the same across congruent and incongruent conditions. Each sentence was presented character by character at fixation, flanked 2 o bilaterally by the preceding character (n-1) on the left and the next character (n+1) on the right. Each viewing consisted of three characters presented on the screen for 100 ms with an inter-stimuli interval (ISI) of 400 ms. Twenty-four participants' ERPs were recorded individually with 40 tin electrodes (10-20 System) in a sound-attenuating, electrically shielded booth. The EEG and EOG signals were sampled at 500 Hz and filtered digitally offline with a 0.02 to 30 Hz band pass. Epochs of interest were selected time-locked to the onset of the critical trials with a 200 ms pre-onset baseline window and a 1000 ms window after onset. Mean ERPs amplitudes from 300~450 ms and 800~950 ms were computed for each participant and tested for significance using ANOVA. A more negative N400 component was found between 300 and 450ms when the sentence context was incongruent than when it was congruent with the right flanker. Furthermore, no significant differences between the two conditions were found between 800 and 950ms, which was the time window of the N400 effect when the target noun was fixated foveally. Since the critical trials were the same across conditions and different lexical properties in the parafovea were avoided, the only manipulation was the semantic congruence of the target noun with the prior context. Thus the significant difference in the N400 component between 300 and 450ms suggests that semantic extraction from the parafoveal word exists during the first 100 ms of current word fixation in Chinese sentence reading. These results suggest that the semantic information of a preview word may be processed in parallel with the fixated word, which supports the view of GAG models (such as SWIFT). Together with the results of previous studies, the present study also demonstrates that the flanker-RSVP ERPs paradigm may be a suitable method for the study of parafoveal processing during sentence reading.