These datasets corresponds to a time-based prospective memory task. The experiment took approximately one hour to complete: around 20 minutes to set up the electrode net and adjust impedances, plus approximately 40 minutes to complete the task. In the first part of the task participants completed the ongoing task only (~10 minutes). The second part of the experiment consisted on the same ongoing task plus the time-based prospective memory task (~25 minutes). Ongoing task: This consisted of a continuous 1-back categorisation task, in which participants had to decide if the previous word on the screen belonged to the same semantic category as the current word on the screen. Participants were instructed to press a key on a response pad with their right index finger for ‘related words’ (when the word belonged to the same category) and to press a different key with their middle finger for ‘unrelated words’ (when the word did not belong to the same category). Time-based prospective memory task: Participants were instructed to reset a clock every four minutes by pressing the first key in a response pad with their left index finger. A digital timer showed up in the centre of the screen for one second every time participants reset the clock, showing the exact time in minutes and seconds counted from the previous clock reset (MM:SS). Participants were also allowed to do clock-checks, which were performed by pressing the second key on the response pad with their left middle finger. Clock-checks displayed the same timer on the screen (MM:SS), with the only difference that the clock was not reset