This study builds upon previous research investigating the construct validity of phraseological complexity as an index of L2 development and proficiency. Whereas previous studies have focused on cross-sectional comparisons of written productions across proficiency levels, the current study compares the longitudinal development of phraseological complexity in written and oral productions elicited over a 21-month period from learners of French. We also improve upon the state of the art by including L1 data to benchmark learner levels of phraseological complexity. Phraseological complexity, operationalized as the diversity (no. types) and sophistication (PMI) of adjectival modifiers (adjective + noun) and direct objects (verb + noun), was generally higher in learner writing as compared to speaking. Over the study period, the sophistication of phraseological units increased slightly but developmental patterns were found to differ between tasks, highlighting the importance of considering task characteristics when measuring phraseological complexity.

本研究建立在先前研究的基础上，该研究调查了作为二语发展和熟练程度指标的短语复杂性的结构有效性。之前的研究主要集中于不同熟练程度的书面作品的横断面比较，而当前的研究则比较了法语学习者在 21 个月的时间内书面和口头作品中措辞复杂性的纵向发展。我们还通过纳入 L1 数据来衡量学习者的短语复杂性水平，从而改进了现有技术。与口语相比，学习者写作中的短语复杂性（可操作为形容词修饰语（形容词+名词）和直接宾语（动词+名词）的多样性（数量类型）和复杂性（PMI））通常更高。在研究期间，措辞单元的复杂性略有增加，但发现任务之间的发展模式有所不同，这凸显了在衡量措辞复杂性时考虑任务特征的重要性。