A slot is a type of gambling machine with a fixed paytable and reels that spin when a button is pressed. The symbols on the reels match a winning combination to win a prize. Many slot games have bonus features that increase the chances of winning. These can include wild multipliers (a 2X symbol on the reel doubles your winnings), progressive multipliers where the number increases with each spin, and free spin bonuses.

Slot game developers use a Random Number Generator to determine the positions of the symbols on each reel. The RNG cycles thousands of numbers each second. When the player presses the “spin” button, the program stops at a random set of symbols. The player can then press the “spin” button again to continue to play.

Players enjoy slots because of the intermittent rewards that they offer. They also provide a form of escape from painful emotional experiences, such as depression or anxiety. Moreover, the high fidelity, attention-grabbing music and animations that accompany wins and losses distract players from thinking about negative aspects of their lives. It is not surprising, therefore, that the two measures of in-game reward reactivity we report in this article are positively correlated. In addition, the measure of reward reactivity correlates with retrospective ratings of positive affect variance. Unlike psychophysiological measures of reward processing that require cumbersome electrodes and wires that reduce ecological validity and may inhibit flow, our measures are completely unobtrusive and can be incorporated into a variety of games.