In a few seconds, a rolling millisecond timer will appear inside the box below. The numbers will be displayed in red. Please right click with a mouse, if on a laptop, or touch the red numbers, if on a cell phone, to click on the red numbers as fast as you can. This will stop the timer and briefly display your reaction time. The timer will reappear at random intervals for 3 minutes, so you will need to pay close attention. Each 3-minute test needs to be completed all at once, so you should not leave until the test is over. Press the start button below to begin.