Proficient bilinguals make less superstitious choices revisiting the FLE in light of L2 proficiency

Abstract The relationship between language and other domains of cognition is a key area of interest in bilingualism research. A relevant phenomenon in this regard is the Foreign Language Effect (FLE), which suggests that individuals may make more rational decisions when using a second language (L2) compared to their native language (L1). Here, by replicating a previous study, we investigated how different levels of L2 proficiency influence superstitious beliefs among bilingual individuals, beyond the language (L1 or L2) in which they are tested. Our findings showed no significant differences in superstition levels between the L1 and L2 contexts. However, we found that greater L2 proficiency was linked to lower superstition levels in both languages. These results suggest that L2 proficiency, or variables associated with it, plays a key role in shaping rational decision-making and may lead to inaccurate estimates of the FLE if it is not adequately controlled for. This study advances our understanding of the FLE by emphasising the importance of considering L2 proficiency in research on bilingual cognition and judgement.