Shortly you will be presented with three letters for 5 seconds. After the letters have been removed a three-digit number will appear. Immediately start counting backwards by threes out loud as fast as you can, starting from the displayed number. If you lose track or forget the number, pick a different number and start over. It is vital that you do this task as quickly as you can. There will be a beeping tone to indicate how fast you should try to count. Do your best to keep up. In no case should you stop. For this experiment to work, it is vital for you to be completely engaged in these intervening tasks.