Bottom-up influences on voluntary task switching in different reward contexts?

In humans, voluntary task switching is susceptible to bottom-up influences like a switch of the target stimulus identity (Mayr & Bell, 2006). A recent study with ants (Czaczkes, Koch, Fröber, & Dreisbach, 2018) has shown that even irrelevant cue changes increase switching behavior, but only if they are presented within a high-reward context. To investigate whether a reward context would also increase switching behavior in response to meaningless cue changes in humans, we conducted two voluntary task switching experiments. On each trial, participants chose between two tasks preceded by one of two different color cues. Reward prospect was manipulated between blocks (Experiment 1: no vs. high reward; Experiment 2: low vs. high reward). In both experiments, the cue change did not modulate the voluntary switch rate. However, the voluntary switch rate was significantly lower in high-reward blocks as compared to no-reward or low-reward blocks. This suggests that bottom-up influences on deliberate task switching in humans are limited to task-relevant information. Moreover, the finding of a decreased voluntary switch rate within a high-reward context further supports the claim that unchanged high reward prospect promotes cognitive stability.