Dual N-Back

When the player press the "Play" button, the application will begin. Then, the game level is chosen. Notice that 2 things happen: A yellow box appears and an audio recording of a letter is played. Remember where the box appeared and also remember the letter. After a few seconds, another box appears and another letter is said. If the chosen level is 2, the 2-back game is considered. This means that you need to remember if a letter was repeated or a box appeared in the same location 2 times ago. If the third letter said is the same as the very first one, that's an audio match. If the box appears in the same location as where the first box appeared, this is a visual match. Press "Position" for visual matches, "Sound" for audio matches and "Both" when both match. Continue to press these keys whenever the present squares/letters match what appeared/was said 2 times ago. Eventually, if the player is good enough, the level can be increased by pressing "N+1".