Quote:When the trigger on the Zapper is pressed, the game causes the entire screen to become black for one frame. Then, on the next frame, the first target area is drawn in all white as the rest of the screen remains black. On the next frame, the next target area is drawn in white. The Zapper detects this change from low light to bright light, as well as which frame the change was detected. This is how the game knows which target has been hit.[7][8][9] After all target areas have been illuminated, the game returns to drawing graphics as usual. The whole process is almost imperceptible to the human eye.