| This study investigated relationship between mental-attentional ( M-) capacity, executive functions, and oral production in development of writing in two genres. Children in grades 3,5, and 7, as well as adults, completed oral and written tasks in the narrative and persuasive genres. Children attended two schools that differed in writing curriculum. A holistic and a developmental scale were used to assess quality of written texts. In addition, participants received tasks tapping M-capacity, shifting, updating, and expressive vocabulary ability. Holistic and developmental scores increased with age in children. There were no differences between schools in terms of holistic scores obtained on oral tasks. However, schools differed in holistic and developmental scores on written tasks and on syntactic complexity in writing. Scores on measures of shifting and updating increased with age. M-capacity scores increased with age until grade 5, but did not differ significantly in grades 5 and 7. Scores on measures ofM-capacity, shifting, and updating did not differ by school, suggesting that within grade, children in the two schools were matched in terms of ability. Adults received lower expressive vocabulary and holistic scores than grade 7 students on written tasks, which suggested that child and adult samples may not have been comparable. Multiple regression analyses showed that M-capacity and updating contributed significantly to variance in scores on written persuasive and narrative tasks, respectively, even after accounting for Age. Contrary to expectation, shifting did not contribute unique variance to scores on written tasks. Mediation analyses showed that M-capacity mediated the relationship between Age and persuasive writing. Additionally, updating mediated the relationship between Age and narrative writing, and between M-capacity and persuasive writing. These findings call into question results of previous studies that emphasized the role of shifting in writing. In addition, the comparison between the two schools points to the role of vocabulary and experience in learning to write. Finally, results suggest that oral exercises highlighting genre-specific features may help children achieve higher levels of writing quality. |
