Slot machines: how a loss is made to look like a win

After lunch, Miva tries a slot machine. It has 5 reels, spinning columns of pictures, and 15 lines across them. She plays all 15 lines at 10 cents each, so each spin costs her $1.50.

Lights flash, music plays, and the screen says WIN: 50 cents. Miva smiles. But the spin cost $1.50, so she just lost $1.

Scientists in Canada call this a loss disguised as a win. On one popular machine, with 15 lines played, it happens on 18 spins in 100. That is more often than a real win, 14 spins in 100. In their lab, new players' skin sweated a little after these losses, just as after a real win.

Next, Miva tries an older machine with three spinning reels. She gets two stars on the line, and the third star stops just above it. So close! This is a near miss. On many machines, it is not an accident.

Inside, a computer picks where each reel stops. It picks from a hidden list of stops, much longer than the reel you see. The star is on that list once. The blank spots just next to it are on it many times. So the star often shows just above or below the line, and seldom on it. In 1989, the Nevada Gaming Commission, which makes the rules for casinos there, allowed this way of making near misses.

Does it work? In a lab in Cambridge, people liked near misses even less than plain misses. Still, after a near miss they said they wanted to play more, and the parts of the brain that react to a win lit up. Both tricks make a loss feel less like a loss. And each press of the button is one more bet with the house edge.

Miva walks away $20 down and sure of one thing: she was close. Tomorrow night, she says, she will beat Rono's table. She has a system.