Aims: Within the current multilingual paradigm shift, transfer is increasingly conceptualised not only as an unintentional mechanism of “interference”, but also as an intentional mechanism used as a learner strategy. However, very little is known from an empirical perspective about (un)intentionality in transfer. This article builds on an exploratory study which suggested that background language words that fit well within the morphological constraints of the target language are highly activated during target language use and, consequently, likely to transfer unintentionally. The present study tests whether the correlation between morphological similarity and unintentionality in lexical transfer is statistically significant

Methodology: A quasi-Poisson regression analysis was employed to test the significance of morphological similarity on the amount of unintentional transfer in the written production of Spanish by 78 highly multilingual school students, when tested together with additional variables (number of languages known, proficiency in the target and source languages, frequency of use, first language/second language status and psychotypology) that have also been proposed to affect lexical activation and transfer.

Data and analysis: A picture-story description task was used to elicit written transfer. When a learner reported – introspectively or retrospectively – a word to have been transferred from a background language, this word was coded as an instance of intentional transfer. Reversely, non- target-like words traced back to a background language by the authors that were not commented on by the learner were coded as instances of unintentional transfer.

Findings: A strongly significant (p < 0.001), positive correlation was found between the amount of unintentional transfer and morphological similarity. A negative trend (p<0.1) was also found between amount of unintentional transfer and number of languages known by learners. Theoretical implications are discussed.

Originality: This is one of few studies shedding light on (un)intentionality in transfer. It is also one of few studies to employ regression analysis to investigate the effect of several variables on transfer.

Significance: The study provides empirical evidence to substantiate theoretical accounts of lexical activation. First, the results show that morphological similarity indeed seems to be the primary variable leading to high levels of cross-lexical activation and, second, the results show how highly activated words are more likely to be transferred unintentionally, further supporting these theoretical accounts.

Traditionally, transfer is described as interference and consequently as an unintentional mechanism. More recently, however, the perception of control in transfer has changed and it is now commonly accepted that transfer can occur both automatically and strategically. Studies have previously employed think-aloud protocols during writing tasks to establish the degree of intentionality in transfer. However, this method does not let us distinguish between instances of transfer that are truly unintentional and instances that were simply not commented on due to the constraints imposed by the think-aloud protocol. The present study, therefore, conducted a stimulated recall interview in direct succession of the think-aloud protocol in order to categorise also those instances of transfer that were not commented on initially. With data from highly multilingual adult learners of Catalan, the study examines the proportion of unintentional and intentional transfer in relation to (1) different types of transfer, (2) different source languages of transfer and (3) different word classes in transfer. The data indicates that some of these aspects of transfer tend to occur unintentionally, whereas others are more prone to be used intentionally. The theoretical implications of the results, as well as their limitations, are discussed.

The study reported in this thesis investigates the source language of lexical transfer in multilingual learners using a mixed methods approach. Previous research has shown that the source language of crosslinguistic influence can be related to factors such as proficiency, recency/exposure, psychotypology, the L2 status, and item-specific transferability. The present study employed a mixed methods approach in order to best serve the particularities of each of the five factors under investigation. Multinomial logistic regression was emloyed to test the predictive power of the first four factors, thereby addressing the issue of confounding variables found in previous studies. A more exploratory qualitative analysis was used to investigate item-specific transferability due to the lack of prior empirical studies focusing on this aspect. Both oral and written data were collected, offering an analysis of modal differences in direct comparison. The results show a significant effect of proficiency and exposure, but inconsistent patterns for psychotypology. Most importantly, in this study of lexical transfer, a significant L1 status effect was found, rather than an L2 status effect. In addition, the statistical model predicted the source language of transfer better in the spoken than in the written mode. Finally, learners were found to assess, as well as actively improve, an item’s transferability in relation to target language norms and constraints. All of these findings contribute to our understanding of lexical organization, activation, and access in the multilingual mind.