The importance of functional adequacy as an essential component of L2 proficiency has been observed by several authors (Pallotti, 2009; De Jong, Steinel, Florijn, Schoonen, & Hulstijn, 2012a, b). The rationale underlying the present study is that the assessment of writing proficiency in L2 is not fully possible without taking into account the functional dimension of L2 production. In the paper a rating scale for functional adequacy is proposed, containing four dimensions: (1) content, (2) task requirements, (3) comprehensibility, and (4) coherence and cohesion. The scale is an adaptation of the global rating scale of functional adequacy, which in an earlier study was carried out with expert raters (Kuiken, Vedder, & Gilabert, 2010; Kuiken & Vedder, 2014). The new rating scale for functional adequacy was tested out by a group of non-expert raters, who assessed the functional adequacy of a corpus of argumentative texts written by native and non-native writers of Dutch and Italian. The results showed that functional adequacy in L2 writing can be reliably measured by a rating scale comprising four different subscales.

In a study on L2 proficiency in writing, conducted among 84 Dutch university students of Italian and 75 students of French, manipulation of task complexity led in the complex task to a significant decrease of errors, while at the same time a trend for a lexically more varied text was observed (Kuiken and Vedder 2005, 2007, in press). Based on this first analysis in which some global performance measures were used, a more specific analysis was carried out. In the latter analysis, which is reported in this article, accuracy was investigated in more detail according to the type of errors in the L2 texts, while lexical variation was analysed further by distinguishing frequent words from infrequent ones. Results showed that the effect of task complexity could mainly be attributed to lower ratios of lexical errors in the more complex task. With respect to the use of frequent versus infrequent words mixed results were found. On the basis of these findings a number of implications with regard to the operationalisation of task complexity and linguistic performance are discussed.

This study puts the Cognition Hypothesis (Robinson 2005) to the test with respect to its predictions of the effects of changes in task complexity (± few elements) and task condition (± monologic) on L2 performance. 44 learners of Dutch performed both a simple and a complex oral task in either a monologic or a dialogic condition. The performance of the L2 learners was analysed with regard to linguistic complexity, accuracy, and fluency. As predicted by the Cognition Hypothesis, the complex task generated more accurate though less fluent speech. Linguistic complexity, however, was only marginally affected. Dialogic tasks triggered more accurate and fluent output though it was structurally less complex. The interaction of task complexity and task condition showed effects on measures of accuracy only: in the monologic but not in the dialogic condition task complexity did promote accuracy. As a consequence, our results only partially support the Cognition Hypothesis

The chapter discusses the question to what extent the effect of task complexity on linguistic performance in L2 writing and speaking is influenced by the mode in which the tasks have to be performed (oral versus written). The majority of studies which have been conducted so far in the framework of either the Limited Attentional Capacity Model (Skehan, 1998; Skehan & Foster, 2001) or the Multiple Attentional Resources Model (Robinson, 1995, 2007, this volume) concern oral task performance. While some studies have also looked at the effect of task complexity on the written production of L2 learners, there are no studies to our knowledge in which the effect of task complexity on linguistic performance in relation to mode has been investigated. For that reason a study was set up where two tasks of different task complexity, which already had been submitted to L2 learners in the writing mode, were presented to a group of L2 learners as speaking tasks. The participants in the oral mode were 44 learners of Italian as a second language, with Dutch as their mother tongue. Their performance was compared with that of another group of 91 Italian L2 learners with Dutch L1 who had performed the same tasks in the written mode. Scores on a cloze test were used as a measure of the general level of L2 proficiency of the learners. Our results demonstrate that both in the oral and the written mode task complexity mainly seems to affect accuracy, in particular with respect to lexical errors. We did not observe an interaction of task type and proficiency level, either in the written or in the oral mode.

This study explores to what extent syntactic complexity as assessed by four types of complexity measures may vary in written, argumentative texts of L2 learners (A2‐B1) and native writers of Dutch, Italian and Spanish. All texts were assessed by calculating both overall complexity measures and more fine‐grained measures that focus on the type and number of coordinate and subordinate structures, and the use of post‐modifiers within the NP. The results of the study indicate that there is variation in the process of gradual complexification in written L2 production across proficiency levels, across languages, and between L2 and L1. In line with findings from earlier research, this study shows the importance of employing both general and more specific complexity measures for assessing syntactic growth in L2.