Slots are casino games in which players insert cash or, in the case of “ticket-in, ticket-out” machines, paper tickets with barcodes, into designated slots on a machine to activate the reels and receive credits based on the machine’s paytable. Most slot games have a theme, with symbols and bonus features that are aligned with the theme. While the majority of gamblers enjoy the game as harmless entertainment, a small subset can experience severe gambling problems.

The most popular type of slot is the video slot, which uses representations of spinning reels on a computer screen. In some video slots, the reels may be weighted to allow for more potential combinations and increase top payouts. Other common features include wild symbols, which substitute for other symbols (except scatters or other special symbols); and random and progressive multipliers that increase with each winning spin. In addition, many video slots incorporate bonus games that award players with free spins, pick-a-prize interactions, or mystery bonuses. These extras add to a player’s enjoyment and can provide a significant portion of their total winnings. In our study, we introduced two measures of reward reactivity that gauge how much players enjoy slot play. Unlike other psychophysiological measurements that involve cumbersome electrodes or wires, these measures do not interfere with the gaming experience and are unbiased estimates of a player’s affective responses to wins. The results show that these simple measures are significantly correlated with positive affect ratings and uncorrelated with PGSI or depression scores, suggesting that they capture a fundamental aspect of slot enjoyment.