Fig. 2.

Cognitive tasks. A Switch task consisting of 3 sections: 1 numbers had to be clicked in ascending order (non-switch). 2 Letters from A to Z had to be clicked alphabetically (non-switch). 3 Numbers and letters had to be clicked alternately in ascending order (switch, i.e., 1-A–2-B–3-C). B 2-back task. Images with fruits and vegetables were displayed on a computer screen. Participants were instructed to press a defined button when an image matched an image 2 trials before. C Tonic alertness. When a white circle appeared on a black computer screen participants had to press a button as quickly as possible, the display of a white cross required no reaction