Neural substrates of the interplay between cognitive load and emotional involvement in bilingual decision making

Prior work has reported that foreign language influences decision making by either reducing access to emotion or imposing additional cognitive demands. In this fMRI study, we employed a cross-task design to assess at the neural level whether and how the interaction between cognitive load and emotional involvement is affected by language (native L1 vs. foreign L2). Participants completed a Lexico-semantic task where in each trial they were presented with a neutrally or a negatively valenced word either in L1 or L2, either under cognitive load or not. We manipulated cognitive load by varying the difficulty of the task: to increase cognitive demands, we used traditional characters instead of simplified ones in L1 (Chinese), and words with capital letters instead of lowercase letters in L2 (English). After each trial, participants decided whether to take a risky decision in a gambling game. During the Gamling task, left amygdala and right insula were more activated after having processed a negative word under cognitive load in the Lexico-semantic task. However, this was true for L1 but not for L2. In particular, in L1, cognitive load facilitated rather than hindered access to emotion. Further suggesting that cognitive load can enhance emotional sensitivity in L1 but not in L2, we found that functional connectivity between reward-related striatum and right insula increased under cognitive load only in L1. Overall, results suggest that cognitive load in L1 can favor access to emotion and lead to impulsive decision making, whereas cognitive load in L2 can attenuate access to emotion and lead to more rational decisions.