Poster D46, Monday, March 26, 8:00-10:00 am, Exhibit Hall C
Task switching decomposed: MEG evidence from bimodal language switching
Esti Blanco-Elorrieta1,2, Karen Emmorey3, Liina Pylkkänen1,2; 1New York University, 2NYUAD Institute, 3San Diego State University
A defining feature of human cognition is the ability to quickly and accurately alternate between complex behaviors. This switching process minimally comprises of goal recognition, disengagement from the previous task and engagement in a new task. Previous studies have associated task-switching with prefrontal activity; however, it is unknown how the sub-computations of task switching individually contribute to these activities. This is largely because few natural tasks allow for full separation of disengagement and engagement processes during switching. Here we recorded magnetoencephalography (MEG) from ASL-English bimodal bilinguals who often sign and speak simultaneously. This offers a unique opportunity to dissociate engagement and disengagement. Our MEG recordings showed that turning a language “off” (switching from simultaneous to single language production) led to increased activity in the ACC and PFC, while turning a language “on” (from one language to two simultaneously) did not differ from non-switch trials. The distinct representational nature of the “on” and “off” processes was also supported by multivariate decoding analyses. Granger causality analyses additionally revealed that i) compared to turning-on, turning-off required stronger connectivity between left and right dlPFC and ii) dlPFC activity predicted ACC activity, consistent with models in which the dlPFC is a top-down modulator of the ACC. These results suggest that in language switching, the burden of task-switching lies in disengagement from the previous task as opposed to engagement in a new task, and that in the absence of motor constraints, producing two languages simultaneously is not more cognitively costly than only producing only one.
Topic Area: LANGUAGE: Other