本文探讨和对比了六级、雅思、托福写作部分的反拨效应机制。研究发现：总体上，成就型考试使用以考试价值为中介影响语言学习和应试备考；工具型考试使用直接影响语言学习；考试设计以考试价值为中介影响语言学习，以价值和期望共同作为中介影响应试备考。工具型考试使用对语言学习、考试设计对考试价值、考试价值对应试备考的影响上，三项考试存在显著差异。本文证实了反拨效应在写作测试上的特定性，以及在不同考试之间的变异性。

The present study explored and compared the washback mechanisms of CET-6, IELTS and TOEFL writing modules. The results showed that, in general, achievement test use influenced language learning and test-oriented preparation, mediated by test value; instrument test use directly influenced language learning; test design influenced language learning via test value, and influenced test-oriented preparation via both value and expectancy. The washback mechanisms of the three writing modules differed significantly with regard to the influences of instrument test use on language learning, test design on value and test value on test-oriented preparation. This paper corroborates the specificity of washback in writing modules and the variations of washback among different tests.