2.3.1 Picture-naming task
The response language in picture-naming trials was determined by a color cue. In each trial, a picture with a red, blue, or spliced border appeared. In the forced and natural switching blocks, only red and blue cues were used. Participants were instructed to name the pictures based on the color cues provided. It is important to note that monochromatic cues were presented in both forced and natural contexts. This was done to maintain a ”forced” constraint in the natural switching block. With this manipulation, if we still observe that the advantages of forced switching context outweigh those of natural switching context, then the benefits of forced switching can be more effectively elucidated. In the voluntary switching block, the language cue was spliced with a red and blue border, indicating that participants were free to decide in which language to name the picture. The color-language associations were counterbalanced across participants. Based on whether the language of the current trial was the same as the immediate preceding trial, two type of trial sequences were classified: switch trials (i.e., the response language was different from the preceding trial; L2-L1, L1-L2) and non-switch trials (i.e., the response language was consistent with the preceding trial; L1-L1, L2-L2). Picture stimuli, trial types, and response languages were pseudo-randomized throughout the task such that there were no more than three consecutive trials of the same response language.