Bilingual education has witnessed a major shift towards mixing two languages in the
classroom. However, adequate methods taking into account the needs of today’s highly
multicultural world require scientific testing. Translanguaging is a method of learning in
which students produce an output of their learning in a language different to that of
instruction. So far, insights into the potential benefits of this method have been
exclusively qualitative. The aim of this thesis was to quantify the benefits of
translanguaging for new knowledge acquisition. In the main experiment (Chapter 4) I
have found neuroscientific evidence for facilitated access to existing semantic
representations for items used in learning mediated by translanguaging as compared to
control items presented in a monolingual learning context. Participants were tested
using a picture-picture priming paradigm after a learning phase involving either English
or a code-switch between English and Welsh simultaneous with a switch between
reading and speaking. Beyond the expected effect of semantic relatedness on the mean
N400 amplitude, well known to index semantic processing effort (Kutas and Hillyard,
1980), a striking main effect of translanguaging on the same N400 was found,
suggesting that relevant semantic representations had become selectively more
accessible in long-term memory. Moreover, this effect could still be measured 2 to 4
weeks later without participant training. In chapters 5 and 6, I have set out to test the
two components of translanguaging separately in order to determine the contribution to
the overall effect of code-switching on one hand and comprehension-to-production on
another. Chapter 5 focuses on the automaticity of semantic priming and the potential
impact of code-switching on the N400 in Welsh-English bilinguals. Chapter 6 focuses
on the effects of the comprehension-to-production switch on the N400 in Basque-Spanish bilinguals