In the 0-back task participants watched a series of letters (100 trials) appear on the screen. They were instructed to press thekey every time a letter appeared, unless it was the letter E (occurring in 20% of trials), in which case they were to press the J key. The 1-back task was identical to the 0-back task, except that instead of pressing J when an E appeared, they pressed J whenever a letter matched the preceding letter. The 2- back task was identical to the above tasks, but the J key was to be pressed when a letter matched the last but one letter. Henceforth, trials requiring an F response will be termed non-events and those requiring a J response will be termed events. These tasks will also be referred to collectively as n-back tasks.