关键词: 眼动与脑电同步技术, 自然阅读, 心理语言学

Abstract: Brain-electric correlates of reading have traditionally been studied with word-by-word presentation, called serial visual presentation (SVP), a condition that eliminates important aspects of the normal reading process and precludes direct comparisons between neural activity and oculomotor behavior, so that the results obtained by this method had lower ecological validity, which was difficult to be popularized. And EM only describes a summation of all cognitive processing occurring during reading, which can not show the sequence of the cognitive processes. This paper presents a new methodology for studying psycholinguistic, which combines eye movements (EM) and electroencephalogram (EEG) to track the time course of cognitive processes. This technique has the advantage of coupling accurate time measures from Event-related potentials (ERPs) and the location of the eye on the stimulus, which can compensate for the lack of EM and ERPs, so it can be used to explore the time course of cognitive processes and its neural mechanism in the process of reading under the natural reading condition. The realization of this technique needed two computers, which were connected through parallel ports. The computer A was used for stimulus presentation and the eye-movement acquisition. And the computer B was used to collect the EEG signals by means of EEG amplifier. It should be noted that eye tracker and EEG amplifier must have the same sampling rate. The computer A would send a synchronization signal (TTL Pulse) to computer B as soon as the stimulus was presented on the screen. The synchronization signal could allow the EM and EEG signals to be recorded simultaneously, which could provide an accurate mark for the off-line analysis of EEG data. It should be pointed that saccde offset or the onset of the first fixation were treated as the reference mark of EEG segment obtained by co-registration of eye movement and EEG record, which was different from traditional ERP off-line analysis. Some studies have begun to make use of this technique to explore fundamental phenomena of psycholinguistic and the mechanism of prafoveal processing during reading, and made some valuable outcomes through this technique. For example, Dimigen, Kliegl & Sommer（2012）utilized co-registration of EM and EEG and combined the boundary paradigm to investigate the neural mechanism of parafoveal preview effect. The results demonstrated that a correct parafoveal preview during the previous fixation could lead to a modulation of fixation-related potentials (FRP) amplitude over occipitotemporal areas. This component could be located to extrastriate occipital or occipitotemporal cortex. At last, based on the problems existing in this technique and its application prospect, some advises have been put forward for the future: (1) A standardized procedure should be developed for the processing of data obtained by co-registration of EM and EEG. (2) More indexes should be selected in using the approach of co-registration of EM and EEG recording. This can achieve more valuable results. (3) Because of the uniqueness of Chinese characters, some studies have found that some effects are different from the alphabetic characters. Therefore, co-registration of EM and EEG recording should be widely used in Chinese reading.

Key words: Co-registration of EM and EEG, Natural reading, Psycholinguistic