The Effect of Task Complexity on Fluency and Lexical Complexity of EFL Learnersʹʹ Argumentative Writing

Based on Robinson’s (2003) Cognition Hypothesis and Skehan’s (1998) Limited Attentional Capacity Model, this study explored the effect of task complexity on the fluency and lexical complexity of 60 university EFL students’ argumentative writing. Task complexity was manipulated through applying resource-dispersing factors. All participants were randomly assigned to the one of the three groups: (1) topic, (2) topic + idea, (3) topic + idea + discourse marker group. One-way ANOVA was utilized to detect significant differences among the groups. Results showed that increasing task complexity (1) produced significantly less fluency, and (2) did not lead to differences in lexical complexity (measured by the ratio of lexical words to function words and lexical density), but it did lead to significant differences when mean segmental type-token ratio was used to measure lexical complexity. Further findings and implications are discussed in the paper.