Cognitive control (CC) is an important prerequisite for goal-directed behaviour and often associated with dysfunctional prefrontal activity within the cortex. This can be ameliorated by non-invasive brain stimulation. In this randomised single-blind study we compare effects of transcranial direct current stimulation (tDCS) on CC in healthy subjects. The study includes 162 subjects who undergo a two-week (six sessions) training of cognitive control (adaptive paced auditory serial addition task, PASAT) supported by tDCS. Subjects are randomised to receive either concurrent anodal, cathodal, or sham tDCS with an intensity of 1 mA or 2 mA of their left (F3) or right (F4) PFC, resulting in eight stimulation groups. Stimulation effects on performance changes are compared to a sham control group.Changes in Affective state are measured by the positive and negative affect schedule (PANAS), possible transfer effects are assessed by the Eriksen Flanker task. Stability of effects is measured up to three months after the last intervention.

Inclusion Criteria:

• Healthy subjects
• Right-handed (assessed by Edinburgh Handedness Inventory)
• No other concurrent brain stimulation during participation
• Proficient in German (min. CEFR level B)
• Ability to strictly adhere to study timeline

Exclusion Criteria:

• Diagnosed neurological illnesses
• Diagnosed psychiatric disorders
• Achromatopsia
• Metallic implants / tattoos on or near electrode sites
• Consumption of tobacco to an equivalent of ten or more cigarettes per day
• Prior participation in experiments involving the PASAT