A slot is a narrow opening into which something can fit, such as a coin or a letter. A slot can also refer to a position on a schedule, as in “The program got a new time slot on the broadcasting schedule.”
In modern machines, reels are controlled by microprocessors and symbols are displayed on a screen. When a player presses the spin button, a computer algorithm determines the random number combinations that will appear on each reel. If the symbols line up with a winning payline, the player earns credits according to the machine’s paytable.
Historically, slot machines have operated in a variety of ways. The first machine, designed by Sittman and Pitt in 1891, used a series of drums to display poker hands. When a winning hand appeared, the machine would emit a celebratory jingle and pay out coins or paper tickets with barcodes. More recently, electromechanical slots have allowed for a wide range of payout schemes including 3- and 5-coin multipliers. Video slot machines, which simulate reels on a monitor, became popular in the 1970s.
Despite their popularity, slot machines pose several challenges for psychophysiological research. For one, players often experience very different emotions when they win and lose. Moreover, many of the measures used in previous studies involve cumbersome electrodes or wires that may diminish ecological validity and inhibit flow. These limitations are important to address in future research on reward reactivity in slot machine players.