Slots are games in which players try to win credits by matching symbols on a payline. They are one of the most popular forms of gambling, with some of the largest jackpots in casino history. While most gamblers engage in this activity for entertainment, a small proportion of people experience serious problems with their gambling behavior (Blaszczynski, Sharpe, Walker, Shannon, and Coughlan, 2005). These include financial difficulties, interpersonal difficulties, and involvement in criminal activities to support gambling.

Today, slots are primarily electronic video machines that offer many more combinations than the physical reels of older electromechanical machines. They also can incorporate multiple paylines, which allow for more winning combinations than traditional single-reel machines that could only physically accommodate a limited number of possible stops on each reel. Additionally, many modern slot machines use “weighted” reels to increase the likelihood that certain symbols will appear on a payline. This can create near-miss scenarios, where a symbol seems to be so close to completing a winning combination that it almost feels like luck. But these scenarios are a part of the game’s design and not a result of a lack of skill or chance.

While there is little doubt that slots are a form of gambling, the study reported here offers two important contributions to research on gambling enjoyment. First, it provides psychophysiological measures of reward reactivity that are simple to administer and do not require cumbersome electrodes or wires that reduce ecological validity and may inhibit flow. Second, it shows that the two measures of reward reactivity are unrelated to negative aspects of slot play, such as problem gambling and depression.