Being bilingual has a social advantage of making us more adaptable in this interconnected and diverse world. But as our cognitive resources are limited, using different languages has some consequences. This project has studied the cognitive and neural consequences of being bilingual in the cognitive domain of Memory.
The main aim of this project was to study the influence of linguistic pattern in the information access and retrieval. Linguistic pattern was defined by language age of acquisition, proficiency and language use and exposure in everyday life.
More specifically, the aims of this project were 1) to understand the consequences of being Monolingual versus Bilingual in true and false memories; and 2) as experience and environmental input change the brain, this projects studied if being bilingual modulates brain areas engaged in remembering correctly and falsely.
In order to study this, we used Deese-Roediger-McDermott paradigm (DRM) because it is sensitive to linguistic manipulations on memory. In this paradigm, after studying several word lists (e.g. bed, rest, tired, dream, wake,…) converging on a semantic theme captured in a word that is never presented during study (e.g. sleep), participants perform an old/new recognition test that includes studied words (e.g. rest; target), semantically related non-studied words (e.g. sleep; critical lure), and other new non-semantically associated words (e.g. flower; unrelated lure). Participants typically exhibit a high rate of false memories to Critical Lures (CL), which is thought to reflect semantic relational processing during encoding. DRM lists could vary in their tendency to elicit false memories based on their associative strength. In this project the associative strength was manipulated using high and low associative strength lists.
We conducted a series of behavioral experiments using DRM paradigm: comparing Spanish and Basque languages in Bilingual group; comparing Monolingual and Bilingual groups in the same language, Spanish; and comparing Monolingual group in Spanish with Bilingual group in Basque.
And we conducted an fMRI experiment as well, comparing Monolinguals and Bilinguals in Spanish. In all the experiments associative strength was manipulated. And language proficiency, age of acquisition, and language use/exposure were controlled.
The results from this project show that being Bilingual decreases false memory rate only when intrusions are semantically associated with the studied words. Importantly, higher false memories for Monolinguals than Bilinguals were observed across high and low associative strength conditions and language comparisons. Overall, the use of a second language in our everyday life modulates the access and retrieval of words.
fMRI results revealed that left Inferior Frontal Gyrus (IFG) was significantly more activated in Bilinguals than Monolinguals for both, true and false memories. And this area was more activated for low than high associative strength conditions. These results are consistent with previous evidence showing that the IFG is engaged in semantic tasks requiring active strategies and effortful processing. And this suggests a less automatized or more effortful semantic access in Bilinguals than in Monolinguals.
