In tDCS, direct electrical currents at the intensity of 2 mA are generated by an electrical stimulator and are noninvasively delivered to the left and right dorsolateral prefrontal cortex through a pair of saline-soaked sponge electrodes (7×5 cm) for 30 minutes.

In tRNS, direct electrical currents at the intensity of 2 mA amplitude (offset at 1 mA) and frequency of 100-640 Hz are generated by an electrical stimulator and are noninvasively delivered to the left and right dorsolateral prefrontal cortex through a pair of saline-soaked sponge electrodes (7×5 cm) for 30 minutes.

In sham group, placebo stimulation is generated by an electrical stimulator and is noninvasively delivered to the left and right dorsolateral prefrontal cortex through a pair of saline-soaked sponge electrodes (7×5 cm) for 30 minutes.

In tDCS the electrical current is applied directly between electrodes mounted on the head which can can de-or hyperpolarizes resting membrane potential and thereby modulate cortical excitability

The test begins with a number of coloured squares (boxes) shown on the screen. The aim of this test is that by selecting the boxes and using a process of elimination, the participant should find one yellow 'token' in each of a number of boxes and use them to fill up an empty column on the right-hand side of the screen.

The participant is shown two displays containing three coloured balls. The test administrator first demonstrates to the participant how to move the balls in the lower display to copy the pattern in the upper display and completes one demonstration problem, where the solution requires one move. The participant must then complete three further problems, one each requiring two moves, three moves, and four moves. Next, the participant is shown further problems and must work out in their head how many moves the solutions require and then select the appropriate box at the bottom of the screen to indicate their response

The Positive and Negative Affect Schedule (PANAS) is a self-report questionnaire that consists of two 10-item scales to measure both positive and negative affect. Each item is rated on a 5-point scale of 1 (not at all) to 5 (very much).