A slot is a slit or narrow opening, usually in a door or wall, for receiving something, such as a letter or coin. It may also refer to:

A gaming machine that uses a random number generator (RNG) to determine the position of symbols on its reels. A player inserts cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode into a slot and activates the machine by pushing a lever or button (either physical or on a touchscreen). The RNG cycles thousands of numbers each second, and when the program stops at a random set of symbols, the player wins the prize according to the pay table. Symbols vary by game, but classic examples include fruits, bells, and stylized lucky sevens.

The appeal of slot machines is largely due to the fact that they offer fast, immediate feedback. In addition to a visible display of the winning combination, most machines also emit high-fidelity attention-grabbing music and amusing animations in response to monetary gains. These features make a slot machine’s output akin to a variable-ratio reinforcement schedule, and they increase the enjoyment that players derive from playing the game.

In the current study, we report two new measures of reward reactivity, which gauge how much players enjoy playing slots. Unlike other psychophysiological measures that involve cumbersome electrodes and wires (and potentially reduce ecological validity), these new measures are unobtrusive and allow researchers to examine the enjoyment associated with a wide range of slot games.