Recent studies showed that switching between affectively salient and neutral task sets leads to asymmetrical switch costs, which has been ascribed to affectively salient stimuli gaining accelerated access to attentional resources. Here, we investigated the influence of affectively salient food stimuli and fasting state of subjects on task performance and task choice in a voluntary task switching paradigm, in which the neutral task required categorisation of digit stimuli as odd or even. The affective food task required categorisation of food images as sweet or savoury. Fasting duration amounted to 14 and 18 hours in Experiment 1 and 2, respectively.

In Experiment 1, we observed asymmetric switch costs, with larger switch costs when switching away from the food task to the digit task as compared to switching to the food task. Longer fasting duration increased this asymmetry by increasing the costs when switching from food to digit task in Experiment 2.
Despite these effects on response time switch costs, task choice and switch rate were not affected by either stimulus content nor fasting.

These results suggest that the affective salience of the stimuli facilitates the activation of the corresponding food task-set in working memory causing difficulties in deactivating the task when switching to the neutral digit task. In addition, the larger state of hunger further increased subjects’ difficulties to deactivate the food task set as shown by the larger fasting-related asymmetry of switch costs in Experiment 2 compared to Experiment 1. Importantly, hunger did not affect the subjects' task choice.