A slot is a narrow depression, groove, notch, or slit, especially one for receiving or admitting something, as a coin or letter. A slot in a piece of wood can be used to hold nails or screws. A time slot on a broadcasting schedule is a position in which a program may be played.

A significant subset of gamblers have serious gambling problems (Blaszczynski, Walker, Shannon, & Coughlan, 2005). These problems can lead to mounting financial debt, marital difficulties, work-related issues, and involvement in illegal activities to support their habit. Nevertheless, the majority of gamblers find that gambling is enjoyable, especially if they play slots.

In the research reported here, we investigate whether psychological factors explain this allure. We use two psychophysiological measures to gauge reward processing during slot machine play. Unlike other psychophysiological measures that utilize cumbersome electrodes and wires to monitor brain activity, our measurements are entirely unobtrusive, allowing subjects to play their favorite slot machines in the same way they would on the casino floor.

The first measure measures arousal, using a continuous, attention-capturing feedback process. The second measure measures reward reactivity, using a monetary stimulus. Both measures are assessed during a series of experimental trials in which players spin three reels and win credits. The amount of credits won is then recorded using LabChart software. A force transducer is fixed underneath the spin buttons of each simulator, and the amount of pressure applied to the button translates into a volt signal that is recorded by AD Instruments PowerLabs equipment and saved in LabChart.