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.