An ERPs Approach To The Cognitive Processing Mechanism Of Chinese Evidential Causals

Most of the previous studies have demonstrated that readers show greater difficulty in processing evidential causals than logical causals. Logical causals refer to the causal relations following natural physical and social sequences of events, while evidential causals do not refer to the causal relation following normal sequence of events in the real world, but mean the evidences that enable the speaker to make such statements(Liao Qiaoyun, 2011, p.102). Moreover, Liao Qiaoyun(2011, 2014) conducts the theoretical framework of construal mechanism of evdential causals and makes a further classification on Chinese evidential causals into Chinese evidential causals without evidential marker and Chinese evidential causals with evidential marker. As far as the previous studies are reviewed, little research touches on the mental processing mechanism of Chinese evidential causals by adopting effective empirical approaches. Based on the findings and limitations of the previous studies, the present study adopts the ERPs technique to explore the cognitive processing mechanism of Chinese evidential causals without evidential marker and Chinese evidential causals with evidential marker so as to make sure whether the present study provides the empirical evidences to the construal mechanism of evidential causals proposed by Liao Qiaoyun(2011). The research questions of the present study are presented as follows:Is there any difference in processing the two sub-types of Chinese evidential causals? If there is, what are the differences of the cognitive processing between Chinese evidential causals with evidential marker and Chinese evidential causals without evidential marker? And what is the possible mechanism leading to those differences?The present study is completed in the Key Lab of Cognitive Neuroscience & Foreign Language Learning in SISU. Twelve subjects, all right-handed, take part in theERPs experiment. The age range of these subjects is 22-27(mean: 23). The experimental materials consist of 43 Chinese evidential causals without evidential marker, 43 Chinese evidential causals with evidential marker, and 86 filler sentences. Each sentence is divided into three semantic-parts to be successively presented. After reading the sentence, subjects are required to judge the acceptability of the stimuli.The EEG is collected by the software NeuroScan 4.5. The behavioral data and the ERPs waves are analyzed in an off-line way by the software SPSS 16.0. By comparison of the behavioral data and ERP data of the two sub-types of Chinese evidential causals, the following results are obtained finally.(1) According to the behavioral results, the mean reaction time of processing Chinese evidential causals with evidential marker(1191.302ms) is shorter than that of Chinese evidential causals without evidential marker(2120.796ms). And the degree of acceptability of Chinese evidential causals with evidential marker(97.92%) is higher than that of Chinese evidential causals without evidential marker(87.3%).(2) According to the ERPs results, no difference exists of the mean latency and amplitude of N100 between the two sub-types of Chinese evidential causals in 50-150 time window; but in 150-350 time window, significant differences of the mean amplitude of P200 exist in the three electrodes FPZ(m=1.05255, t=2.693, p=.021<0.05), FP2(m=1.60434, t=3.010, p=.012<0.05), and FP1(m=1.25328, t=3.306, p=.007<0.01) where the P200 amplitude of Chinese evidential causals without evidential marker is more positive than that of Chinese evidential causals with evidential marker; in 350-1100 time window, there exist differences of the mean amplitude of LPC in three electrodes FCZ(m=-1.54342, t=-2.379, p=.037<0.05), CZ(m=-1.39035, t=-2.337, p=.039<0.05), and CPZ(m=-1.51887, t=-2.603, p=.025<0.05) where the LPC amplitude of Chinese evidential causals with evidential marker is more positive than that of Chinese evidential causals without evidential marker. Furthermore, by employing repeated-measures ANOVAs of the brain hemispheres between the two sub-types of Chinese evidential causals, the main effect of brain hemisphere [F(2,11)=7.223, p=.004 < 0.05] and the interaction effect of the brain hemisphere and the two sub-types of Chinese evidential causals [F(2,6)= 6.116, p=.008 <0.05] are yielded in the time course 350-1100 ms. And the negativity of the two sub-types of Chinese evidential causals observed significantly at the left hemisphere is larger than that at the right hemisphere.The conclusions drawn from the behavioral results and ERPs results are to demonstrate that some differences exist in processing the two sub-types of Chinese evidential causals. And the main difference lies in absence or appearance of the evidential marker which not only speeds up the semantic integration of Chinese evidential causals, but also reduces the difficulty of processing Chinese evidential causals. And the cognitive processing mechanism of Chinese evidential causals are inferred from two levels: semantic processing and logical integration of events.To sum up, inferred from the experimental results, the cognitive processing mechanism of the two sub-types of Chinese evidential causals in present study provides the empirical evidences and rationality for the holistic construal framework of Chinese evidential causals proposed by Liao Qiaoyun(2011).