ABSTRACT
Objective:To explore the developmental characteristics of Chinese semantic and orthographic processing in normal school-age children by event-related potential (ERP) technique.Methods:Children aged 7-11 in an ordinary primary school in Changzhou were randomly selected and divided into 7-year old group ( n=21 ), 8-year old group ( n=21), 9-year old group ( n=19), 10-year old group ( n=20) and 11- year old group ( n=22) according to their age.ERP was recorded while subjects completed the Chinese character semantic activation task and pseudo word judgment task. Then the N400 and P200 amplitudes of school-age children under the conditions of semantic correlation, semantic uncorrelation and pseudo word judgment were collected, and the data were analyzed by three factors mixed design ANOVA.Data of behavioral accuracy and response time were analyzed by one-way ANOVA and Bonferroni correction was used for multiple hypothesis testing. The statistical software was SPSS 25.0. Results:(1)Behavioral results: the accuracy of semantic related and semantic unrelated tasks of children in the five groups aged 7, 8, 9, 10 and 11 were statistically significant ( F=15.55, 4.01, both P<0.01), and the accuracy of children in the 7-year old group was significantly lower than those in the other four groups (all P<0.05). There was no significant difference in the accuracy of pseudo word judgment task among the five groups ( F=0.68, P=0.609). The response time of children in the five groups under semantic related and semantic unrelated tasks was significantly different ( F=3.90, 3.13, both P<0.05). The response time of the 11-year old group under semantic related tasks was significantly shorter than those of the 7-, 8- and 9-year old groups (all P<0.05). The response time of the 7-year old and 11-year old groups under semantic unrelated tasks was significantly shorter than those of the 8-, 9- and 10-year old groups (all P<0.05). (2)ERP results: N400 amplitudes of 7-, 8-, 9-, 10- and 11-year old children under semantic related tasks were significantly smaller than those under semantic unrelated tasks and pseudo word judgment tasks (all P<0.05). The N400 amplitude of the subjects gradually decreased with the increase of age, except that there was no statistical difference between the 10-year old and 11-year old groups under the semantic related task, between the 8-year old and 9-year old groups under the semantic unrelated task and the pseudo word judgment task, and between the 10-year old and 11-year old groups (all P>0.05), there were statistical differences between the other age groups (all P<0.05). P200 amplitude of semantic related task at 7-, 8-, 9- and 10-year old was significantly higher than that at semantic unrelated task (all P<0.05), and the amplitude of semantic related task at 7-, 8-, 10- and 11-year old was significantly higher than that at pseudo word judgment (all P<0.05). The amplitude of P200 gradually increased with age, and there were significant differences in pairwise comparison among other age groups ( P<0.05), except semantic related task and unrelated task among 7-, 8- and 9-year old groups, between 10- and 11-year old groups, and pseudo word task between 7- and 8- years old groups, 10- and 11- year old groups (all P>0.05). Conclusion:The semantic processing and orthographic processing of school-age children develop with age in a unique way. The age of 7 is an important period for cognitive development of Chinese language.The age of 8-9 may be a sensitive period for the development of brain plasticity, and the development slows down at the age of 10-11.
ABSTRACT
Objective:To explore the semantic priming processing characteristics of children with Chinese developmental dyslexia(DD).Methods:According to scores of the dyslexia checklist for Chinese children, character recognition test and Raven's standard progressive matrices (RSPM), 19 primary school students from a school in Wuqia County of Xinjiang were selected as DD group.Meanwhile, 19 children were selected as chronological-age control(CA) group matching in age and RSPM scores, and 20 children were selected as reading-level control(RL) group according to the character recognition test and RSPM scores.The amplitude of N400 of children in three groups were tested by semantic priming paradigm under the conditions of semantic related, unrelated and pseudo words.Results:The accuracy of the DD group under the conditions of irrelevant semantics((0.55±0.25) vs (0.81±0.16), P<0.05), and pseudo characters((0.43±0.27) vs (0.68±0.26), P<0.05) were significantly lower than those of CA group.There was no difference between DD group and RL group, as well as between RL group and CA group(both P>0.05). There was no significant difference in the response time among the three groups of children under semantic related and unrelated conditions( F=1.23, 2.03, both P>0.05). In terms of ERP data, in semantic related condition, there was no significant difference in N400 amplitude among the three groups ( F=0.55, P>0.05). In semantic unrelated condition, the amplitude of N400 in DD group was smaller than that in CA Group((-5.92±3.70)μV vs (-9.76±3.45)μV, P<0.05), and there was no statistically significant difference between DD group and RL Group((-5.92±3.70)μV vs (-7.41±4.02)μV, P>0.05), as well as between CA gorup and RL group.As to pseudo words condition, children in DD group had a lower amplitude of N400 than those in CA and RL groups ((-6.03±2.92)μV vs (-9.98±3.40)μV, (-8.91±3.40)μV, both P<0.05). While no significant differences were found between CA group and RL group. Conclusion:Children with Chinese DD have cognitive defects in semantic and orthographic processing.The semantic cognitive defects may caused by their low reading level, rather than their inherent defect, while the defect in orthographic processing may be their inherent defect.